How birds differ from other groups of animals. How birds differ from animals. Classification of modern birds

Birds, like mammals, belong to the class of animals, but despite this unifying feature, birds have a number of abilities and characteristics that significantly distinguish them from mammals.

For many, the most obvious difference comes to mind - feathers and wings. Yes it is. Plumage is characteristic only of birds, otherwise they would not be able to make their flights. Birds belong to vertebrates, and this unites them with mammals, fish, reptiles, allowing birds to be enrolled in a huge biological kingdom - Animals.

Birds originated from reptiles and they owe this to their distant parent - the lizards. The first bird-like creature was the Archeopteryx bird. She lived about 120 million years ago and looked like a lizard, the size of a dove, which moved on its hind legs, had wings, but could not fly. It also had a beak, feathers, set teeth, but a long, twenty vertebral tail from a lizard.


Flights were planning and difficult for Archeopteryx, but it had long, sharp claws, with which the lizard could easily climb trees and make short flights. Following from this, it is safe to say that the progenitor of modern birds was a half-lizard, half-bird, so the relationship of these two classes of animals is obvious.

Who are animals and who are birds

Animals are living organisms that unite into one large kingdom. About 34 types of animals go to this kingdom, which in turn are subdivided into 50 million species of living things.

Birds are the same animals, but the body is covered not with wool, but with feathers. The forelimbs of the birds were modified into wings, which gave them the ability to fly. In total, there are about 10,000 species of various birds.

Comparative characteristics of animals and birds

If birds and animals belong to the same biological kingdom, then the question arises about their differences. What is the difference between these representatives of the animal kingdom?

I must say that all birds are warm-blooded animals who can fly. This extraordinary ability determined and shaped the morphological and physiological characteristics of birds, and also adapted their body to flight. As a result of long evolution, the forelimbs of birds were transformed into wings, and the legs became more massive and muscular. The bird needs massive legs for successful takeoff and landing, and the tail serves as a directional regulator.

Animals, unlike birds, can be both warm-blooded (mammals) and cold-blooded (reptiles, fish, amphibians). Some types of animals have no shelter at all ( flatworms, tunicates, sponges).

The body of a bird, unlike an animal, is covered feathers... The plumage allows you to create a greater streamlining of the body during flight, and at low temperatures the feather retains the heat of the small body of the bird better. The body of an animal, in turn, has a wide variety of coverings. It can be epidermis, scales, chitinous cut, shell, skin, or just wool.

Bird bones are incredibly strong, despite their lightness compared to animal bones. In the process of flight, the fusion and immobility of the body is of great importance. It is provided by the fusion of the vertebrae of all parts of the bird's spine, with the exception of the cervical. Birds, in comparison with animals, have a rather long and elongated neck, and also have a keel. Many types of animals, not including chordates, have no internal skeleton at all.


The digestive system of a bird begins with a beak, which animals do not. Metabolism is accelerated, which is required in order for food to be quickly processed, while providing the bird with the right amount of free energy spent on flight. The circulatory, respiratory, and excretory systems work in an accelerated mode.

TO bird class include warm-blooded vertebrates adapted to flight. Birds are highly organized vertebrates that are widespread on Earth. The total number of species is more than 8500.

Birds differ from all other animals in many structural and biological features associated with flight. An important sign of birds - feather cover... Their aircraft is built from feathers; many vital processes of these animals are associated with them. Feathers are different in structure and function. Feathers lying outside with wide and dense blades are called outline... Under them are located downy feathers.

Main part outline pen- long barrel. The thick end of the trunk entering the skin is called ochin(he was sharpened when he wrote with pens), the trunk does not have a cavity above the point, it is called rod to which is attached fan- a wide blade of a feather that forms a flying surface. Each half of the fan consists of thin horny plates - beard, even thinner processes branch off from each of them - barbs, ending with hooks, with the help of which they cling to the barbs of neighboring barbs (barbs of the first order, barbs of the second order). A feather of such a structure has great resistance to the air, and at the same time, it is very light, which is important when flying.

Under the contour pens there are down feathers whose barbs do not have hooks and do not connect to each other. Therefore, down feathers are always fluffy and very light. Between them, air is retained, which is characterized by poor thermal conductivity, due to which the bird's body is very well protected from heat loss. Thus, feathers serve not only for flight, but also for thermoregulation.

The contour feathers form the flying surface of the wing, which is why they are called flywheels... The role of the bird's rudder is played by long contoured feathers, which are called helmsmen.

With the great work that feathers perform, they quickly wear out, which is why the phenomenon of molting in birds is associated (2-3 times a year). Moulting is especially painful for geese and ducks, since at the same time all flight feathers fall out at once. Then the birds become completely helpless and need special protection from poachers.

The head of birds is small and light, the chewing muscles are greatly reduced: the jaws are thin, covered with light horny sheaths, forming beak... A well-developed neck provides head mobility. The body is dense, streamlined. The forelimbs have become organs of flight - wings... The hind limbs of most birds are small, in flight they are pressed against the body. Many birds on their hind legs have four fingers: three are facing forward, and the fourth is backward ( tarsus).

The tubular bones of birds, unlike other terrestrial vertebrates, do not contain bone marrow and are filled with air. They are lightweight and very transparent. Even the dense and strong bones of the skull of birds are thin and light, growing together to form a very strong skull. The shortening of the caudal spine and the absence of a number of bones contribute to a decrease in the mass of the skeleton. Thus, the skeleton of birds is very strong and at the same time extremely light. In addition, the skeleton has other adaptations for flight: the lumbar and sacral vertebrae are firmly connected, being a support for the body. Ribs are attached to the thoracic vertebrae, which connect from the ventral side to the sternum, forming the rib cage. There is a large protrusion on the sternum - keel, well-developed muscles are attached to it, which set the wing in motion. In the skull of birds, a large rounded cerebral box with large eye sockets and elongated jaw bones, devoid of teeth, are distinguished.

The skin of the birds is dry. At the base of the tail feathers, almost all birds have coccygeal gland emitting an oily liquid. The bird lubricates the feathers with it, which prevents them from getting wet and makes them elastic. The location of the muscles in the bird's body is peculiar: there are almost no muscles on the dorsal side, the bulk is on the abdominal side and the pectoral muscles, as well as the muscles of the lower leg and thigh, are especially strongly developed.

Due to the absence of teeth in birds, there are a number of features in the structure and work of the digestive organs. The esophagus of birds forms a protrusion - goiter, where food gradually accumulates, here it is moistened and softened and then enters the stomach, which consists of two sections: glandular and muscular... In the glandular, food is processed chemically, under the action of gastric juice. In the muscular section, birds have small pebbles with which food is ground, crushed and even more dissolved. Further, the food is processed by the bile of the liver and pancreatic juice and, absorbed by the walls of the short intestine, is assimilated. Digestion takes place in birds quickly, undigested food residues do not linger in the hind gut and are thrown out. All of this is of great importance when flying.

Respiratory organs in birds... The lungs of birds differ from the bag-like lungs of amphibians and from the cellular lungs of reptiles. The lungs of birds have a spongy structure. The bronchi entering them repeatedly branch. A number of bronchial branching ends in the lung cavity, and some, leaving them, expand, forming air bags, which are located between muscles, internal organs and in the tubular bones. Resting breathing is carried out through the expansion and contraction of the chest. Such breathing is impossible in flight. At this time, it is carried out as follows: with each flap of the wing, the air bags are stretched and filled with air, when the wings are lowered, the bags are compressed and the air goes out through the lungs. Thanks to this, the air automatically passes through the lungs twice, and the birds do not suffer from shortness of breath even during very fast flight.

Circulatory organs in birds... The heart of birds, unlike reptiles, four-chamber: consists of two atria and two ventricles. The left half of the heart contains arterial blood, the right half contains venous blood. The movement of blood occurs, as in amphibians and reptiles, in two circles of blood circulation. But arterial blood never mixes with venous blood. Thereby birds have a constant body temperature, in many cases higher than in humans (40-45 ° C). True, in chicks, it fluctuates, and they need to be warmed. Birds are warm-blooded animals.

Excretory organs of birds - paired kidneys... From them, the ureters depart, through which urine enters the cloaca. The bladder is missing.

Bird brain, in comparison with that of fish, amphibians, reptiles, is more developed, especially cerebellum ensuring coordination of movements, and large hemispheres, which leads to a more complex behavior of birds. From sense organs the organs of sight and hearing are most developed. The eyes of birds, like those of reptiles, are equipped with three eyelids: the upper, lower and nictitating membrane.

The organ of hearing consists of three sections: internal, middle and outdoor auditory opening.

Reproduction and development of birds

Birds are dioecious. The male develops two testis, in the female - one ovary... Brood tubes (two vas deferens or oviduct) extend from the reproductive organs to the cloaca. The eggs mature gradually and are laid one at a time at regular intervals. Unlike reptiles, all birds, except for weed chickens, incubate eggs.

The inside of the egg is yolk with on its surface germinal disc... The yolk is covered with a very thin shell and is kept in a liquid squirrel two dense protein cords... The suspended yolk is mobile and is located so that the embryonic disc is always at the top closer to the warm body of the incubating bird. Shell shell dressing protein, at the blunt end of the egg stratified and forms a small air chamber... The egg is covered on top lime shell permeated with pores through which gas exchange of the embryo with the external environment takes place. Outside, the shell has a thin film that protects the egg from microbes entering it.

A bird's egg can develop only when heated (incubated) to a temperature of 38-40 ° C. The duration of incubation in different birds is different: in a pigeon it lasts 15-18 days, in a hummingbird - 10-12 days, in ostriches - 55-60 days, in other birds - from 17 to 21 days.

In the developing embryo, the rudiments of the brain and muscle segments are first formed, then a huge head with rudiments of gill slits is isolated. The heart is laid very early. The limbs are laid in the form of protrusions closer to the fins than to the wing and leg. A few days later, they begin to resemble the legs of terrestrial lower vertebrates. The tail is laid short from the very beginning, but by the number of vertebrae it is closer to the tail of reptiles.

All organs are gradually formed. In structure, they begin to become typical for birds. Finally, having consumed all the nutritive material of the egg, the chick, with the movement of its beak, endowed with a strong tubercle, gouges the shell and hatches.

Depending on the level of development, chicks are distinguished brood and chicks... Broodlings after hatching are quite developed, they can move independently. Chicks are underdeveloped, naked, blind, helpless, only slightly covered with down. They are fed by their parents until they become independent.

In addition, a number of birds take special care of their chicks. This is the selection of places for nesting, its arrangement, camouflage, incubation of eggs, heating and feeding of chicks, cleaning the nest, etc. There are other forms of care. For example, it is known that the cuckoo lays an egg in the nests of other birds, and although it does not incubate eggs itself, it takes care of the future chick: it makes sure that the owner of the nest does not notice the foundling and does not throw it out of the nest. As a rule, in the nest, the cuckoo cubs hatch first and begin to take care of themselves: it throws out the remaining eggs from the nest or even chicks, providing itself with adequate nutrition before leaving the nest. The concern of birds is also manifested in the fact that adult birds, in case of danger, signal an alarm to the chicks, or the female distracts the “invader” to the nest with various maneuvers, pretending to be wounded, beating her wings on the ground and in other ways.

What are the external signs that distinguish a bird from other animals? and got the best answer

Answer from Ђatiana Nuzhin [guru]
Characteristics of the class BIRDS
Birds are a class of vertebrates, whose representatives are well characterized by the fact that their body is covered with feathers and the front limbs are modified into flight organs - wings. With rare exceptions, birds are flying animals, and those species that do not fly have underdeveloped wings. To move on a solid substrate, birds use the hind limbs - legs. Thus, birds, unlike all other terrestrial vertebrates, are bipedal animals. Birds have a very vigorous metabolism, body temperature is constant and high, the heart is four-chambered, arterial blood is separated from venous blood. The large hemispheres of the brain and the sense organs, especially sight and hearing, are well developed.
From a biological point of view, the most characteristic features of birds are, on the one hand, the intensity of metabolism, the intensity of the course of life processes, and on the other hand, movement through the air by flight. These two main features of birds largely determine their biology. It is these properties of birds that fundamentally distinguish them from other groups of vertebrates. Despite the common evolutionary origin of birds and reptiles, the biological differences between these two groups of animals are enormous.
In terms of mobility and the ability to overcome space, birds rank first among terrestrial vertebrates. Greater mobility is associated with great work muscles, with a high expenditure of energy, which require rapid and intense compensation. Despite the fact that the lungs of birds are low stretchable and relatively small. the use of oxygen in them and the supply of oxygen to the body in birds is very intensive, which is explained by the action of the system of air sacs. The active part of the respiratory process in birds, unlike other vertebrates, occurs not only during inhalation, but also during exhalation. The significance of this for the intensification of metabolism in the body is obvious. Arterial blood is completely separated from venous blood, and the work of the heart is very energetic. In this regard, there is also an energetic work of the digestive organs: the bird consumes a large amount of food, and its assimilation proceeds quickly and very completely. All these features are closely related to the presence of a constant body temperature in birds (and the latter to the development of a heat-insulating cover of feathers). The body temperature in birds is higher than in mammals, most often it is close to 42 ° C, in a few species it drops below 39 ° C, but often reaches 45 and 45.5 ° C.
Among other very significant features of the biology and structure of birds, above mention also the features of reproduction. Compared with reptiles, there is, firstly, a weak intensity of reproduction, and secondly, the complexity of the biological phenomena accompanying reproduction, and especially the complexity of the phenomena of caring for offspring. The latter, as it were, compensates for the low fertility. The entire evolution of birds was in close connection with their acquisition of the ability to fly. The emergence of the basic biological and anatomical features of the avian organism should have occurred simultaneously with the emergence and development of mobility in them, and the improvement of their motor capabilities. Paleontological material shows that at a certain stage of evolutionary development, the ancestors of birds were terrestrial running reptiles.

Answer from Inna Kalieva[guru]
Feathers, wings, beak

Answer from Vadim Kotik[guru]
Wings, feathers and beak

Answer from User deleted[newbie]
well, firstly, feathers, secondly, beak ...

Answer from Yanina[guru]
Feathers, beak

Answer from Anyutka Ulyanova[active]
Feathers! And the platypus also has a beak, which, as you know, is not a bird

Answer from B and x p b[guru]
Wings and beak.

Answer from Igor Gosudarev[guru]
Birds do not have a penis. Seem like that ... A platypus has a beak, and someone also has a semblance of feathers, I don’t remember exactly who. Mice have wings, but they are not birds.

Of course, first of all with feathers. After all, only birds have plumage, and without it they would not be able to rise into the air. Along with mammals, reptiles, fish, birds are vertebrates. With the presence of a spine and other features of the structure of the body, they are similar to these of their relatives. We know that birds evolved from reptiles. The bird Archeopteryx (from the Greek words archaios, archaeos - ancient, pteryx - wing), which lived about 120 million years ago, was in fact a lizard the size of a dove and ran on its hind legs. It had bird feathers, a beak set with teeth, and a long tail, unlike a short bird's one, consisted of 20 vertebrae. With the help of the clawed fingers that crowned its forelimbs, Archeopteryx could climb rocks and trees - he was still a poor flyer and apparently made gliding flights. Consequently, Archeopteryx is both a lizard and a bird, which proves the close relationship of these classes of animals. Among the living birds, only the hoatsin living in South America have claws on their wings.

The transformation of an ancient reptile into a bird, that is, a gradual change in the structure of its body, took place very slowly. The head, long body and tail of the lizard form one line. Her whole body is very flexible. A characteristic feature of the skeleton is a long, elongated spine, especially its tail section. The body is carried by two pairs of relatively short legs, rather far apart from each other. Their bones begin at the flat, broad bones of the shoulder and pelvic girdle that connect them to the spine. Strong muscles are not only in the legs. They also run along the entire spine, and therefore the lizards can move, easily wriggling their whole body. Their skin is covered with horny scales. By comparing the skeletons of a lizard and a bird, we can see striking differences. Why did this or that change take place? If the birds remained flexible, like lizards, the body, during the flight, it would take a colossal tension of all muscles in the air to keep the body in the right position in relation to the wings. Therefore, the bones of the lumbar and sacral regions have grown together into a complex sacrum. A keel has developed on the sternum, and the flat pelvis is firmly fused with the spine. The shoulder girdle, pelvis and movably articulated ribs extending from the spine to the sternum, which allow changing the volume of the chest during flight, formed a short torso, similar to the fuselage of an aircraft. The elongated bones of the forelimbs formed the skeleton of the wing. The shoulder and forearm, although also extended, remained almost unchanged. Any aircraft should be as light as possible, and the bones of the birds become hollow, albeit strong. A long tail, like a flexible long body, is a hindrance in flight. Therefore, several caudal vertebrae have grown together into a short coccygeal bone, or pygostyle. Tail feathers are attached to it, so the tail of the birds has become both short and light.

The hand of the forelimb has also changed unrecognizably: in birds, it essentially consists of one long toe (in lizards, out of five). The forelimbs that have turned into wings are no longer suitable for running or climbing, but the bird can spread them during flight and wave them up and down. At rest, she folds her wings along the body. A bird, unlike a lizard, can walk or stand still only on two legs, like a person. To maintain a stable balance on two legs, the direction of the body's gravity should not go beyond the support area, as, for example, in a person whose body is in an upright position. In birds, the trunk is elongated horizontally, so the structure of the legs must have changed. In most vertebrates living on earth, the leg consists of a thigh, lower leg, and foot. In birds, a straight segment departs from the tibia - the tarsus, which is usually covered not with feathers, but with scales. At the lower end of the tarsus there are four toe joints, of which three are usually directed forward and one is directed backward. When the bird is standing or walking, thanks to the tarsus, the fingers are under the center of gravity of its body, and thus it maintains balance.

You can understand how the muscles are located on the body of a bird by straightening out a fried chicken. Many people prefer the breast - the pectoralis major muscles attached to both sides of the keel on the sternum. There are lovers of legs - muscles that stretch from the upper half of the leg and thigh to the pelvis. In other parts of the chicken's body, meaty pieces cannot be found. Weakly developed muscles on the back and wings. And you can't bite off anything at all from the lower part of the leg (tarsus) and fingers, Consequently, all large muscles are located as close as possible to the vertical that passes between the legs. When a bird flaps its wings in flight, it is mainly the strong chest muscles that work. The tendons of the pectoralis major muscles go to the humerus. Their purpose is to lower the wings down. Under the pectoralis major (subclavian) muscles, the wings lift up (their tendons pass over the head of the crow's bone, like a roller, and are attached on the upper side of the shoulder). The forearm and toes also move thanks to long tendons that stretch from the thigh to the lower leg. If the bird bends the joint between the tibia and tarsus, the toes will close as the tendons running back along the joint between the tibia and tarsus will contract. There are, as it were, notches on the tendon, which correspond to the protrusions on the tendon bag. In a bird sitting on a branch, this clamping device operates automatically and the fingers are rigidly fixed in a bent position.

In the thoracic region and below, the spine of birds is motionless, but often their neck is rather long and can bend in all directions. When a lizard hunts, its whole body works. The bird, on the other hand, stretches forward only its neck and aims at the victim with its beak. At rest or in flight, the neck is bent in the form of the Latin letter S. For example, in a flying gray heron, the neck arches so that the head lies on its back, and in front of it only a sharp, like a peak, beak sticks out between the wings. Thus, the head is close to the center of gravity of the body.

Bird class (Aves)

General characteristics (G.P. Dementyev)

Birds are a class of vertebrates, whose representatives are well characterized by the fact that their body is covered with feathers and the front limbs are modified into flight organs - wings. With rare exceptions, birds are flying animals, and those species that do not fly have underdeveloped wings. To move on a solid substrate, birds use the hind limbs - legs. Thus, birds, unlike all other terrestrial vertebrates, are bipedal animals. Birds have a very vigorous metabolism, body temperature is constant and high, the heart is four-chambered, arterial blood is separated from venous blood. The large hemispheres of the brain and the sense organs, especially sight and hearing, are well developed.

From a biological point of view, the most characteristic features of birds are, on the one hand, the intensity of metabolism, the intensity of the course of life processes, and on the other hand, movement through the air by flight. These two main features of birds largely determine their biology. It is these properties of birds that fundamentally distinguish them from other groups of vertebrates. Despite the common evolutionary origins of birds and reptiles, the biological differences between these two groups of animals are enormous.

In terms of mobility and the ability to overcome space, birds rank first among terrestrial vertebrates. Great mobility is associated with great work of the musculature, with a large expenditure of energy, which requires quick and intense compensation. Despite the fact that the lungs of birds are low-stretchable and relatively small, the use of oxygen in them and the supply of oxygen to the body in birds is very intensive, which is explained by the action of the system of air sacs. The active part of the respiratory process in birds, unlike other vertebrates, occurs not only during inhalation, but also during exhalation. The significance of this for the intensification of metabolism in the body is obvious. Arterial blood is completely separated from venous blood, and the work of the heart is very energetic. In this regard, there is also an energetic work of the digestive organs: the bird consumes a large amount of food, and its assimilation proceeds quickly and very completely. All these features are closely related to the presence of a constant body temperature in birds (and the latter - to the development of a heat-insulating cover of feathers). The body temperature in birds is higher than in mammals, most often it is close to 42 ° C, in a few species it drops below 39 ° C, but often reaches 45 and 45.5 ° C.

Of the other very significant features of the biology and structure of birds, it is necessary to mention also the features of reproduction. Compared with reptiles, there is, firstly, a weak intensity of reproduction, and secondly, the complexity of the biological phenomena accompanying reproduction, and especially the complexity of the phenomena of caring for offspring. The latter, as it were, compensates for the low fertility.

The entire evolution of birds was in close connection with their acquisition of the ability to fly. The emergence of the basic biological and anatomical features of the avian organism should have occurred simultaneously with the emergence and development of mobility in them, and the improvement of their motor capabilities. Paleontological material shows that at a certain stage of evolutionary development, the ancestors of birds were terrestrial running reptiles. The ancestors of the ancestors of birds should have, judging by our ideas about general course evolution of the animal world, belong to very ancient groups of primitive archaeosaurs that lived in the Triassic, and perhaps in the Permian period. These were, of course, running terrestrial forms and, apparently, medium-sized animals.

In the Jurassic time, there was an intermediate arboreal form between reptiles and birds - archeopteryx, which already showed some signs of modern birds, in particular feathers or feather-like formations. Thus, at this time, the ancestors of birds changed from a terrestrial mode of life to an arboreal one and, obviously, a constant body temperature arose (the latter is indicated by the presence of plumage in Archeopteryx). The skeleton of Archeopteryx is still far from that of a bird and lacks its most important functional features. The general trend of further stages in the development of birds (after the Jurassic period) is associated with an improvement in their ability to move and with the acquisition of the ability to fly. Although flightless species were encountered later, most of them became extinct or are on the way to extinction, while relatively small but well-flying groups reached the greatest flourishing since the Tertiary period. The latter are also the most numerous among modern birds.

The speed and freedom of movement gave birds great advantages in the struggle for existence and in the history of their development, and they still do.

Birds are found around the globe, with the exception of the interior of Antarctica, in a wide variety of locations and in a wide variety of climates. In 1937, employees of the Soviet polar station observed gulls, guillemots and snow buntings at the North Pole. In Antarctica Amundsen observed Great Skua at 84 ° 26 "S latitude in 1912. The vertical distribution of birds is also very wide, and different kinds inhabit the highest mountain systems of the world, such as the Himalayas and the Andes. Bearded beards, for example, have been observed in Central Asia at an altitude of slightly over 7000 m; Humboldt saw condors in the Andes at an altitude of 6655 m.

The number of birds in different places is different. The largest number of bird species is found in Central and South America: about 1700 species are found in Colombia, about 1440 in Brazil, 1357 in Ecuador, and 1282 in Venezuela. The bird fauna of Congo (Kinshasa) is also abundant, in which (together with Rwanda and Burundi) there are 1,040 bird species. The fauna of some tropical islands is also rich: 554 bird species in Kalimantan (Borneo), 650 in New Guinea.

In the area of ​​African savannas and gallery forests, bird populations are also diverse: 627 species in Ghana, 670 in Cameroon, 674 in Zambia, 871 species in Sudan.

With distance from the tropics, the composition of the bird population becomes poorer. So, in the taiga zone of Europe, Asia and North America, there are about 250 species of birds. The avifauna of some European countries is characterized by the following figures: Great Britain and Ireland - about 450 species (many migratory), Greece - 339 species, Yugoslavia (Serbia - 288 species, Macedonia - 319 species), Finland - 327 species, Norway - 333 species, Portugal - 315 kinds. From Asian countries, 341 bird species have been found in Afghanistan, and 425 species in Japan. There are 775 bird species in the United States of America and Canada. In total, about 8600 bird species are currently known.

Within the USSR, there are several more than 700 species of birds, which is about 8% of the entire world avifauna.

The number of individuals of individual bird species is very different. There are still few exact calculations. In recent years, the International Union for the Conservation of Nature and Natural Resources has been conducting an investigation of the number of rare bird species that are under threat of extinction. It was found that cahoe petrels survived in Bermuda in an amount of about 20 pairs; white American cranes in North America in 1963, 39 individuals were counted; white-backed albatrosses on the island of Torishima in Japan in 1962, 47 birds were recorded; white-billed American woodpeckers in Cuba found about 13 individuals; there were 60-65 birds in the Californian condors in 1960; Japanese ibises on the island of Hokkaido in 1962 were counted approximately 10-15 individuals; takahe shepherds on the South Island of New Zealand counted about 300 individuals; Hawaiian geese in the Hawaiian Islands and in zoos in 1962, 432 individuals were counted. The preservation of all the listed species and a number of others is in danger. It can be added that from the end of the 17th century to the present, 76 species of birds have become extinct, and to a large extent under the influence of human activity.

What are the most numerous bird species? In the Arctic, apparently, the small guillemot bird is the lyurik, in the Antarctic and Subantarctic - the small petrel of the Wilsonian storm petrel, in the tropical seas - the dark tern (tens of millions of individuals of each species).

Of the terrestrial birds, the most numerous are, apparently, the house sparrow and starlings. Estimates of the number of birds are, of course, approximate. conducted in England and Wales (Fisher, 1954). The total bird population there is estimated at 120 million individuals, belonging to 426 species, but 75% of these 120 million belong to only 30 species, each of which is 3% of a million or more. Chaffinch and blackbird are believed to represent approximately 10 million individuals (each species); there are about 7 million starlings, the same number of robins; house sparrows, dunnocks, songbirds, meadow pipits - 3 million of each; rooks 1,750,000; about 1 1/4 million of common buntings, wrens, gray warblers, willow warblers, wood pigeons; 3/4 million jackdaws, larks, blue tit, barn swallows, city swallows and linnet; about 350 thousand greenfinches, great tits, forest pipits, grasshopper warblers, black swifts, reeds, lapwings, mallards, gray partridges. Of course, these figures are approximate. For relatively rare and less numerous birds in England and Wales, the following figures are given: black-headed gulls - about 150 thousand, barn owls - 25 thousand, gray herons - about 8 thousand, crested grebes - about 2% of a thousand. Some birds are on the rise in Britain. So, fulmars - there are about 200 thousand of them - have become 5 times more than there were at the beginning of this century; the number of gannets increased sharply - up to 1/4 million.

In total, according to rough estimates, about 100 billion birds live on the globe, and this alone indicates their great and diverse significance in the life of our planet.

The reactions of the body of birds to unfavorable changes in the external environment are of a completely different nature than in amphibians, reptiles and in some mammals. In all the groups listed above (except for birds), a decrease in temperature reduces the activity of the body, which leads to hibernation when unfavorable conditions occur in nature. In birds, the response to a decrease in temperature is increased movement - migrations or flights, transferring the organism to conditions more favorable for its existence.

However, one should not imagine that the bird, thanks to its freedom and speed of movement, depends little on the influence of the environment, on the situation and conditions of its habitat.

The bird's lifestyle and behavior also depend on the climate in a broad sense (in particular, temperature and light; the absence of the latter limits the possibility of active bird activity, in particular nutrition; a certain intensity and duration of illumination also determines - through the eye and the pituitary gland - the development of the gonads of birds) , and on food and the conditions for obtaining it, and on nesting conditions (in particular, on the availability of a suitable place for a nest and nesting territory), and on population density, from competition, etc.

It is remarkable that birds, however paradoxical it may seem at first glance, are very conservative in terms of habitats. Each species and subspecies lives in a strictly defined area. The observations of Howard and many other scientists, and in recent years and as a result of ringing (marks of caught birds with special rings), have established that the life of each bird is inextricably and closely connected with the "homeland" in the narrow sense, that is, with that relatively small area the earth's surface - groves, forests, fields, etc., where the bird was born. Bird nesting occurs annually (with rare exceptions) on this site or in the immediate vicinity of it. There is a struggle for this nesting territory in the spring. This does not apply only to birds that breed colonially and to species that do not form nesting pairs. Apparently, the very song of passerine birds should be considered mainly as a signal warning other males of the same species that this nesting site is occupied. Migratory birds return to their nesting site in spring, and young (with some exceptions) settle somewhere nearby (but, of course, outside the nesting site of their parents).

The attachment of birds to the place of their homeland is so great that usually the onset of unfavorable circumstances on it causes either a decrease in the rate of reproduction, or non-nesting, or death.

From a general biological point of view, such attachment of birds to the place of their homeland can be explained in general view that for every bird optimal conditions existence at certain times of the year are available in their homeland. Indeed, for example, the extreme north, in addition to calm and convenient places for nesting, low temperatures favorable for cold-loving forms, an abundance of food, also gives advantages in rearing the brood. The non-setting summer sun allows the birds to be active most of the day, and a large amount of light determines and stimulates the development of the gonads. It has been established with sufficient confidence that the daily cycle of birds is closely dependent on the lighting conditions: each species wakes up, behaves actively and rests under a certain lighting intensity, which determines the daytime activity of the bird. The conservatism characteristic of birds in habitats is in direct and close connection with their possibilities of movement, since only flight can bring a bird that has flown away in the fall hundreds and thousands of kilometers from the nesting site back to that small piece of land where it nested last year (or in past years). This, in addition, is associated with the peculiarities of the orientation of the birds, which will be discussed below.

Before moving on to considering individual issues of bird biology, let's say a few more words about plumage, which performs various and very important functions. Bird feathers serve the purpose of thermoregulation, mainly to retain heat, create a "streamlined" body surface and protect the skin from damage.

Although the body of birds is usually completely covered feathers(with the exception of some bare areas - around the eyes, at the base of the beak, etc.), feathers do not grow on the entire surface of the bird's body, but in some specific areas, which are called pterilium, while the non-feathering areas of skin between them are called pharmacies.

Distinguish usually contour feathers, down and some other types of feathers. The structure of the contour pen is as follows. Available tight and resilient kernel, around which, usually symmetrically, is located fan forming a dense, air-tight plate. The part of the rod that directly emerges from the skin and does not carry the fan is called the ochin, the rest of it is called the trunk.

Often, the feather also has a so-called side trunk, which looks like a thin and soft rod with downy beards and in rare cases (for example, in emus and cassowaries) it reaches a great development.

Contour feathers come in a variety of sizes and shapes. Different groups they have different names and have different functions. Among them should be highlighted primary and secondary flight feathers... The first ones, usually 9 or 10 in number, are attached to the back of the hand, they are stiffer than all other feathers and during flight create thrust (to a lesser extent lifting force), their fans are usually asymmetrical. The secondary flight feathers are attached to the forearm (more precisely, to the ulna). Their number is variable and ranges from 6 (in hummingbirds) to 37-38 (in some tube-nosed animals). They make up the wing bearing surface. The tail is formed steering feathers(their number ranges from 8 to 28). The rest of the tail coverts have special names according to their location on the body: upper coverts and lower tail coverts, large, medium, small wing coverts, etc. (Fig. 5).

Down differs from a contour feather in that its core is soft, the fans are also soft and their barbs are not interlocked. The fluff grows either only on pterilias, or on apterias, in some groups of birds - all over the body. Down is used to keep warm.

We now turn to consideration of individual issues of bird biology. Let's start with flight... In the structure of a bird from the point of view of adaptations to certain modes of movement, the following features attract attention. In the skeleton, which is characterized by strength and lightness, the forelimbs are completely freed from supporting the body when walking, standing, and sitting. Their function is mainly reduced to movement by air, that is, flight, and in some aquatic forms (penguins) - to movement in the water. In this regard, the forelimbs do not have grasping functions (although in hoatzin chicks, in which, moreover, the fingers remain free for some time, the forelimb is used for climbing branches). This, in turn, caused changes in the structure of the skeleton of the head and neck. The grasping function is performed by the beak. This is associated with a significant mobility of the occipital articulation, a strong development of the muscles rotating the head and the transfer of the center of gravity of the head back. The cervical spine in birds is very mobile, and the chest is, as it were, carried back. The mobility of the cervical spine is expressed both in the wide possibilities of flexion (both lateral and sagittal), and in the possibility of neck rotation, usually up to 180 °, in owls up to 270 °.

The skeleton of the body, which should serve as a solid support during flight, is inactive. The spine in its thoracic region can bend usually only in the lateral direction (the exception is diving forms and shepherd forms living in shrub thickets). In many forms, a number of thoracic vertebrae grow together into one so-called dorsal bone, a number of vertebrae (lumbar, sacral, tail, sometimes thoracic) grow together with the pelvic bones into complex sacrum... Free caudal vertebrae are few in number, and the terminal caudal vertebrae grow together to form the bone that serves to support the tail feathers pygostyle... The shoulder blades fit tightly to the ribs, being connected to them by a system of ligaments and muscles; the ribs carry backward-directed hook-shaped processes that strengthen the connection between the ribs along the longitudinal axis of the body. The articulation of the bones of the shoulder girdle is extremely strong. Finally, the large size of the sternum provides support for the internal organs during flight, and its large crest (keel) serves as an attachment point for powerful muscles that control the movement of the wing. The trunk skeleton of birds is a strong and inactive box, somewhat reminiscent of the skeleton of an airplane. It can be added that the lungs of birds firmly adhere to the ribs, and the movement of the latter during flight automatically stimulates the work of the breathing apparatus.

In the structure of the limbs, the most feature- fusion of a number of bone elements. The complex sacrum and pelvis, formed by the fusion of a number of vertebrae and pelvic bones, give the hind limbs strong support. The widest and most stable pelvis is characteristic of terrestrial (running) and climbing species, the narrowest is for diving. The femur in birds is short but powerful. Unlike reptiles, the femoral neck is located at right angles to its main part. The mobility of the femur in birds is therefore limited, but the articulation of the femur with the pelvis is extremely strong. The fibula is reduced and, to one degree or another, merges with the tibia, to which the upper (proximal) row of tarsal (tarsal) bones also grows. The lower (distal) row of these bones merges with the three metatarsal bones into one bone, the so-called tarsus... In birds, therefore, there is not an ankle, but an intertarsal (intertarsal) articulation. Such a device of the leg gives it greater strength and stability. In particular, the fusion of the metatarsal bones makes it easier to maintain balance when the bird lands on the ground or on a branch. The strong and long stump facilitates the take-off take-off and makes the bird more stable. Birds' toes are well developed and represent a wide variety of adaptations to locomotion. In forms that live in swampy places and move on soft surfaces, they are very long. In running terrestrial forms, they are strong, but rather short, and in the groups most specialized for movement on the ground (ostriches, etc.), a reduction (decrease) in the number of fingers is observed, as in mammals. In arboreal forms, there are complex adaptations to the coverage of branches and certain correlations (dependencies) between the length of the fingers and the size of the knots on which certain species sit. Swimming membranes develop in aquatic forms.

Birds have four or three toes on their feet. The first toe is usually turned backward, often poorly developed, and is absent in the case of a three-toed leg. The African ostrich has only two toes.

The forelimb of birds - wing- extremely peculiar. The final part of it is arranged very simply, since a significant number of bones grow together. The wing fingers of birds do not protrude outward and are covered by a common skin; only three fingers; the number of phalanges of the fingers is small (usually one or two phalanges in the first toe, two or three in the second and one in the third); the distal bones of the wrist and the bones of the metacarpus fuse to form one bone; only two of the proximal carpal bones are preserved. Separate elements of the carpal wing section are inactive, and the whole of it serves as a solid support for the flight feathers. In this case, the first finger carries a winglet, the second finger carries the first, second and third primary flywheels, the third finger carries the fourth primary flywheel, the rest of the primary flywheels are attached to the wrist.

The strength of the parts of the skeleton carrying the primary flight feathers is of great importance for flight, since it is these feathers that are for the bird a tool for moving forward (and at the same time lifting), while the secondary flight feathers, located along the direction of the air flow, perform only the task of keeping the bird in the air and lifting it.

The strength of the skeleton of birds, in addition to the fusion of its individual elements, is also determined by the composition (the abundance of mineral salts) and the structure of the bones; lightness is explained by the airiness (pneumaticity) of many bones associated with the systems of air sacs - pulmonary and nasopharyngeal. Therefore, the relative weight of the skeleton in birds is small.

Due to the vigorous functioning of the limbs and poor mobility of the trunk, the muscles of the wing and legs are highly developed in birds, and the muscles of the trunk are relatively poorly developed. The neck muscles are very complex and functionally varied, which ensures the mobility of the neck. The pectoralis major muscle, lowering the wing, constituting about 1/14 in birds of prey, in a goose 1/11 of the total body weight, is known to be located on the chest, between the humerus and the keel of the sternum. However, the size of the pectoral muscles is not directly related to the size of the wing. Birds with a large wing surface, in particular those that use predominantly soaring flight, have relatively underdeveloped wing muscles. Birds with a small wing surface have strong muscles. Generally speaking, the musculature of birds is distinguished by high density, mobility, and long tendons.

Of the features of the musculature of birds, one should also mention the peculiar structure of the tendons of the muscle - the deep flexor of the fingers, which creates an automatic clamping of the branch with the fingers of a sitting bird. The deep flexor tendon of the fingers has an uneven surface, covered, as it were, with notches, which correspond to the protrusions, or ribs, on the wide and free bag of the tendon. In a bird sitting on a tree, under the influence of its weight, this jig is compressed and the fingers are fixed in a bent position. This adaptation is especially developed in passerines, but apparently all birds have it (only ratites and penguins do not have it).

Birds move on a wide variety of substrates; they generally move well on the ground, climb trees, many dive and swim in the water, but the most characteristic way of bird movement is still flight.

There are few flightless forms among modern birds. Some of them (ostriches, emus, cassowaries, rhea, kiwis, penguins) may never have flown, others have lost their ability to fly, no doubt a second time.

The aerodynamic picture of the movement of birds through the air is very complex. The nature of the flight of individual groups and species is very diverse and is directly related to both their ecological properties (sea, land, arboreal; catching sitting or flying prey, etc.), and with their evolution. The structure of the wing (length and proportions, the length of the flight feathers, etc.), the ratio of body weight to the area of ​​the wings (the so-called weight load), the development of muscles are the main factors that determine the properties of flight in birds.

The flight of birds can be divided into two main categories: this soaring, or passive, flight and waving, or active, flight.

When soaring, the bird moves in the air for a long time, without flapping its wings and using the ascending air currents that are formed due to the uneven heating of the earth's surface by the sun. The speed of these air currents determines the height of the bird's flight. If the air stream moving upward rises at a speed equal to the speed of the bird falling, then the bird can hover at the same level; if the air rises at a speed exceeding the speed of falling of the bird, then the latter rises up. Using the differences in the speed of the two air streams, the uneven effect of the wind - its strengthening and weakening, changes in the direction of the wind, pulsation, air - a soaring bird can not only stay in the air for hours without spending much effort, but also rise and fall. Terrestrial soaring species, for example, vultures feeding on carrion, etc., usually use only ascending air currents. Soaring marine forms - albatrosses, petrels that feed on small invertebrates and are often forced to descend and rise to the water - usually use the effect of wind action, differences in the speed of air currents, air pulsations and eddies. Soaring birds are characterized by large sizes, long wings, long shoulder and forearm (a large development of the bearing surface of secondary flight feathers, the number of which in vultures reaches 19-20, and in albatrosses even 37), a rather short brush, relatively small heart sizes (since the passive flight does not require increased muscle work). The wing is sometimes wide (terrestrial species), then narrow (marine species).

Flapping flight is more difficult and more varied than hovering. It is worth comparing the flight of a swift, the flight of a raven slowly moving its wings, a kestrel fluttering in the air and a peregrine falcon rushing swiftly at its prey, a fast-flying duck and a pheasant flapping heavily in order to be convinced of the validity of this remark. There are various and rather contradictory attempts to classify different types of flapping flight, which we will not dwell on here.

The bird usually uses more than one type of flight, but combines them depending on the circumstances. It should also be borne in mind that flying movements consist of phases successively replacing one another. The flapping of the wings is followed by phases when the wing does not make rowing movements: this is a gliding flight, or soaring. This flight is used mainly by birds of medium and large sizes, with sufficient weight. Small birds usually work vigorously with their wings all the time, or at times can fold their wings, pressing them to the body. The latter is especially characteristic of finch birds.

Acceleration in flight is achieved by a bird by increasing the weight load of the bearing surface, for which it is necessary to fold the wings somewhat. A slow-flying bird has a fully extended tail and spread wings. As the movement accelerates, it folds down the flight feathers somewhat, and in all well-flying birds they form a continuous surface (in a falcon, gull, swift, swallow, etc.).

Great importance for the speed of movement of birds has a wind. Generally speaking, a tailwind or somewhat crosswind is favorable for flight, but a headwind is favorable for take-off and landing. A tailwind during flight increases the bird's flight speed. This increase is quite significant: for example, according to observations of pelicans in California, it was found that an increase in the speed of air movement from the actual calm to 90 km / h contributed to the change in the flight speed of pelicans from 25 to 40 km / h... However, a strong tailwind requires a lot of effort on the part of the bird to maintain the ability to actively control the flight.

The duration and speed of flight of birds is very great, although exaggerated ideas are usually widespread in this respect. The very phenomenon of migration shows that birds can make long movements. European swallows, for example, overwinter in tropical Africa, and some waders nesting in North-East Siberia fly away for the winter in New Zealand and to Australia.

The speed and altitude of birds are significant, although they have long been surpassed by modern flying machines. However, the bird's flapping wing gives it many advantages, primarily in maneuverability, over modern aircraft.

Modern technical means (observations from aircraft, high-speed shooting, radars, etc.) made it possible to more accurately determine the flight speed of birds. It turned out that when flying, birds, on average, use high speeds than when moving outside the migration season.

Rooks on flights move at a speed of 65 km / h... The average speed of their flight outside the time of migration - during the nesting period and during wintering - is approximately 48 km / h... Starlings on migrations fly at a speed of 70-80 km / h, at other times 45-48 km / h.

According to observations from airplanes, it was found that the average speed of movement of birds during flights varies between 50 and 90 km / h... So, gray cranes, herring gulls, large sea gulls fly at a speed of 50 km / h, finches, siskins - 55 km / h, killer whales - 55-60 km / h, wild geese (different types) - 70-90 km / h, wiggles - 75-85 km / h, waders (various species) - on average about 90 km / h... The highest speed was noted for the black swift - 110-150 km / h.

These figures refer to the most intense spring migrations and are likely to reflect the highest bird speeds. Autumn migrations proceed much more slowly, for example, the flight speeds of storks on autumn migrations are hardly half the speed of their spring movement.

The question of the flight altitude of birds remained unclear for a long time. The old idea that the movement of birds takes place, as a rule, at high altitudes (500-1600 m above sea level), raised doubts. However, astronomical observations have shown that, in all likelihood, the maximum flight altitude of birds reaches 2000 and even 3000 m... To some extent, this has been confirmed by the use of radars.

It turned out that flights in spring occur at higher altitudes than in autumn, that birds fly at higher altitudes at night than during the day. Sparrow birds, such as finches, fly at altitudes slightly less than 1500 m; larger passerines, such as thrushes, at an altitude of 2000-2500 m... Sandpipers fly at an altitude of about 1500 m.

Although flight is the main and most characteristic mode of movement of birds, other very diverse modes of movement are also characteristic of them. The well-known divisions of birds into aquatic, terrestrial, and arboreal indicate the well-known differences between these groups in relation to movement. For terrestrial birds, running and walking are typical, for water birds - swimming and diving, for tree birds - jumping and climbing on branches and trunks of trees. It is clear that this division is schematic and does not exhaust the entire complexity of bird movements.

Birds climbing trees have highly developed claws on their paws, the fingers can be widely spaced, often with the fourth toe extending far forward. Pikas, nuthatches, woodpeckers, parrots can serve as an example of birds climbing trees. Birds climbing a tree from bottom to top have a rigid tail with pointed helmsmen as a support during climbing. Legs of climbing birds are short, flexor muscles are strongly developed. The main phalanges of the toes are short. Arboreal birds, jumping and climbing on branches, have highly developed deep flexor tendon clamping devices. In parrots, the legs are widened, and their fingers can be widely spaced; when climbing, they are also helped by a beak, strong and mobile.

Birds with long wings usually do not move well on the ground. Swifts cannot, for example, walk at all. Toadstools and loons walk poorly on the ground. They, like the guillemots living on rocks, have their tarsus facing straight ahead, which increases the stability of the birds when sitting. A good adaptation to increasing the supporting surface when walking is the elongated outgrowths on the fingers that develop by the winter in most grouses, and in the grouse - claws (in winter they are longer) and the plumage of the fingers; this makes it easier for them to move on the snow. Many birds living on swampy soil have long fingers, for example, the fingers of the yakans running along the leaves of aquatic vegetation are very long. Well-walking and running birds have long legs, and long tarsus and tibia (for example, waders, shepherdesses, partly chickens). The ability to run reaches its greatest development in ostriches and rheas. Emu can run at a speed of 31 km / h... An earthen cuckoo can reach speeds of up to 20 km / h, quail - up to 15.5 km / h.

Many birds swim and dive: anseriformes, petrels, copepods, some waders, terns, gulls, guillemots. Swimming and diving birds have widely spaced shortened legs (the thigh and tarsus are shortened), so on land they waddle. They are characterized by a rigid and tight plumage. In aquatic birds, the coccygeal gland is usually well developed, but, judging by the latest data, its function is not directly related to the impermeability of the plumage. The body of swimming birds is usually elongated, and of diving birds it is flattened. The proportion of swimming, and especially diving birds is significant, approaching one in cormorants and grebes. In diving birds, the legs are usually far back, the pelvis is narrow, the wing bones are flattened, and the absolute and relative dimensions of the wings are insignificant. It can be said that well-diving birds are, as it were, on their way to losing their ability to fly; apart from reluctantly flying and heavily flying birds, among the divers there are also flightless ones (the Galapagos cormorant, the recently extinct "wingless" auk, etc.). For diving birds, it is also characteristic to place the center of gravity of the body backward, which facilitates the immersion of the back of the body and legs into the water and, in conjunction with the flattened shape of the body, makes it easier for the bird to maintain balance.

Swimming in the water, the bird acts with its legs, which are carried back and pulled up; at the same time, the legs lie almost horizontally, the thighs are directed forward and downward. Toes with membranes serve as a blade of a propeller or oar, swimming movements are reduced mainly to straightening and bending the tarsus. To accelerate movement in the water, the bird raises and lowers the thigh and moves the lower leg back and forth. This work of the legs of the swimming bird is ensured by the strong development of the muscles that lower the thigh, extend the metatarsus and flex the toes. Birds row with one or two feet at once, while on the water pushes or kicks from the opposite side are used to turn (when turning right - left, when turning left - right).

Diving and scuba diving are of two types. Some birds swim underwater with their wings (as if flying), others with their legs. There are also intermediate types. The first group includes penguins, the second group includes diving ducks, cormorants, loons and grebes. Guillemots use both wings and legs when diving. A deer running along the bottom of streams spreads its wings to stay in the water (a small specific gravity of a dipper would otherwise contribute to pushing it out of the aquatic environment to the surface). A special method of diving, associated not with swimming under water, but only with diving, in diving petrels, gannets, terns, osprey; these birds, rushing to prey, from scattering descend into the water and then immediately get out to the surface.

Ducks, geese, coots, cormorants and other birds tirelessly move throughout the day in the aquatic environment. The energetic work of the locomotor system, heart and lungs allows diving birds to stay under water for a long time. Auk can stay under water 1-2 min, polar loon - slightly more than 3 min, black-throated loon - 2 min, cormorant - more than 1 min, turpan - up to 3 min, big merganser - up to 2 min, American coot - 3 min... These are the maximum numbers. The maximum depths for diving for great crested grebe - 7 m, polar loon - 10.2 m, black-throated loons - 6.1 m, red-throated loons - 8.8 m, great cormorant - 9.4 m, turpan - 7.2 m, mergansers - 4.1-5.6 m, tags - 4.8 m... Penguins swim under water for about 10 m / sec, toadstools - about 1 m / sec.

For the existence of each species of animals, it is necessary to resolve three main tasks: nutrition, reproduction and protection from dangers for the preservation of individuals and species in the struggle for existence. Movement in vertebrates, and in particular in birds, is one of the most essential elements of an animal's defense. Having considered the aspects of bird biology related to it, let us move on to considering their nutritional features.

Conditions nutrition to a large extent determine the course of life phenomena in birds. They affect the geographical distribution of birds, seasonal movements, the rates of reproduction and mortality, and the conditions of intraspecific and interspecific competition. The need to eat a certain type of food determines the feeding stations of each species. Seasonal changes in the environment partly cause changes in nutritional conditions, partly change the norm of the body's need for food (in the cold season, with a large loss of heat by the body, more food is required). The migrations and migrations of birds are also known to be related to feeding conditions.

The feeding regime of individual species is very different. It changes with the seasons and with the age of the bird. Some species are highly specialized in nutrition (stenophages), others do not show preference for a certain type of food (euryphages). Birds feed on both plant and animal food, the latter generally prevailing.

Let us dwell on the most important features of the structure of birds associated with the conditions and methods of feeding. With relatively few exceptions (in particular, owls and predator birds), birds take food with their beak. The shape of the beak is therefore very diverse (Table 3). Birds that get food from water or from the ground (storks, herons, waders, etc.) have long beaks. In these birds, there is a correlation between the length of the beak and the length of the legs and neck. These are usually non-floating forms. On the other hand, a long beak is characteristic of some tropical forest birds that feed on the fruits of woody plants - toucans and hornbills. The large size of the beak in these birds is compensated by the highly developed pneumatic skull. Finally, a long beak is found in many species that suck flower nectar (many hummingbirds, honey suckers, etc.) or in birds looking for food in the folds and depressions of stones or bark (pikas, wall-climbers). In birds, whose beak serves to hold live and sometimes large prey, it is of moderate length or even short, but equipped with a steep hook at the end of the upper jaw (cormorants, owls, daytime predators), and sometimes a barb (falcon). In birds grabbing large prey, the lower jaw is usually large and high (herons, storks, guillemots, gulls); but sometimes in birds that feed on vertebrates, the lower jaw is small, short and low (carnivorous, owls), in the latter case, the grabbing of prey is usually carried out with strong armed paws. In birds that seize insects in flight - swallows, swifts, flycatchers - the beak is not long, but wide and, as it were, flattened, and the slit of the mouth goes far back. They, like other insectivorous birds, have hard bristles on the edges of their mouths, making it easier to catch insects. Woodpeckers, hammering a tree, have a very strong, straight and chisel-like beak; its action is complemented by a long tongue, the end of which is seated with sharp spike-like protrusions that firmly hold the insect. In the crossbills that hatch coniferous seeds from the cones, the jaws cross crosswise and form a lever for raising the cone scales. Granivorous passerines (finches, etc.) have a short, strong, wide and high beak; the palatal surface bears sharp grooves and ridges in them; all this is a device for biting and crushing seeds and seeds of fruits.

Modern birds have no teeth. Among the early Tertiary species, there were also forms with teeth, but at least from the Middle Eocene, toothed birds were no longer found. Chopping food is done in birds either by the beak (for example, in predators), or by combined movements of the beak and tongue (in granivores), or by the stomach. The prey is often adhered to with one or two legs. Woodpeckers and nuthatches grind food items (cones, acorns, etc.), pinching them in a tree (the so-called "woodpecker forges"). Crows, seagulls and, perhaps, a bearded man crush hard prey (crayfish, shells, bones, etc.), throwing it from a height to the ground. The variety of methods of crushing and pre-processing of food also determines the variety of structure and functions of the tongue in birds (Fig. 8). In many forms, the tongue is rudimentary and serves only to isolate airways; such is the language of cormorants, pelicans, gannets, kingfishers, hornbills, hoopoes, ostriches and some petrels. However, the tongue performs the same function in other species (the mechanism is as follows: when a bird holds food in its beak, the end of the tongue rests against the gap in the middle of the palate and makes it possible to use the nasal cavity for breathing). In other birds, the tongue serves as a "probe" (woodpeckers, nuthatches), a suction pump (hummingbirds, honey suckers, sunbirds), a grasping organ (parrots), a brake for holding slippery prey (penguins), a grater (birds of prey), and finally, a complex sieve (flamingos, ducks, geese). Birds have no taste buds on the tongue - they are located on the palate, under the tongue and in the pharynx. The sense of taste in birds is developed quite significantly: birds distinguish sweet, salty, sour, and some types of birds and bitter.

Salivary and mucous glands in the oral cavity in birds are relatively poorly developed; they are completely absent in copepods that swallow slippery prey captured in water.

Esophagus birds are quite extensible, especially in species that swallow large prey (pelicans, gulls, herons, cormorants); characteristic and frequent formation, the so-called goiter- glandular enlargement of the esophagus. In those birds that immediately consume a large amount of food, but sometimes starve for a long time, the goiter serves as a reservoir for food that gradually enters the stomach. In others, for example in chickens, parrots, pre-processing of food begins already in the goiter. In predators, undigested parts of food accumulate in the goiter - bones, wool, feathers, etc.

The anterior part of the stomach of birds - the so-called glandular stomach- performs the functions of chemical processing of incoming food, and the rear - gizzard- processes food mechanically. The posterior (lower) end of the stomach is separated from the intestine by a ring-shaped constrictor muscle (sphincter), which prevents bone debris and other hard or sharp parts of food from entering the small intestine. In fish-eating bird species (egrets, cormorants, toadstools, penguins) and some others, there is also a third section in the posterior end of the stomach, the so-called pyloric sac; its function is to prolong the presence of food in the stomach for better processing. The glandular stomach is most developed in birds that immediately swallow a large amount of food (in fish-eating and carnivorous).

The secretion of the digestive glands in birds acts very vigorously: in marabou and many carnivores, it completely or significantly dissolves bones, and in cormorants, herons and ducks - fish scales. But owls and shrikes do not digest bones at all. Chitin, keratin and fiber are indigestible for all bird species (the latter, perhaps, in chickens, duck and pigeons, is partially absorbed due to the activity of intestinal bacteria).

The gizzard in some birds is characterized by a strong development of muscles, which also form tendon discs. In this case, the walls of the stomach work like millstones and grind hard and coarse food. This is the structure of the gizzard in granivores and birds that feed on solid arthropods and molluscs (chicken, anseriformes, ostriches, cranes, many passerines, many pigeons). In other birds, the musculature in the gizzard is insignificantly developed, and it continues mainly the chemical processing of food with enzymes flowing down from the glandular stomach. This is the structure of the gizzard in meat-eating, fish-eating and fruit-eating birds.

In many bird species, the tubular glands of the muscular stomach secrete a secret, which then forms a periodically changing hard keratin membrane, the so-called cuticle. It is also an apparatus for grinding food. Finally, in many birds, the mechanical effect of the gizzard on food is enhanced by the fact that they swallow sand, pebbles or hard seeds of plants.

Digested food travels from the stomach to the intestines, first to the duodenum, then to the small intestine. Most birds have cecum. Sometimes they carry digestive functions, sometimes they are at the same time a lymphatic-epithelial organ, sometimes only the last; in some species, the cecum is rudimentary or even absent altogether. They reach the greatest development in herbivorous birds (however, there are exceptions). The rectum in birds serves for the accumulation of undigested food debris; its end goes into cloaca- an organ common to birds and reptiles. The ducts of the urinary and reproductive systems also open in the cloaca, and in it, on the dorsal side, there is a so-called fabrication bursa, which undergoes reduction in adult birds (at the age of 8-9 months), but is well developed in young ones. The function of this bag is to form lymphatic cells and oxyphilic leukocytes.

Liver in birds it is relatively very large, its bile ducts flow into the duodenum. Most species have gall bladder, which is associated with the need to simultaneously supply the intestines with a large amount of bile (for processing watery and fatty foods). Pancreas in birds it has a rather varied shape, but it is always well developed and relatively larger than in mammals. Its size and importance are inversely proportional to the gallbladder: it is largest in granivores, smaller in meat-eating birds. The relative total energy turnover in birds is very high, especially in small passerines, while in large species it approaches the value of the energy turnover of mammals. In a hooded crow, for example, at an ambient temperature of 20-22 ° C, the total energy turnover is 840 feces by 1 m 2 body surfaces per day, for a hawk - 780 feces, in a chicken (at a temperature of 23 ° C) - 580 feces; at the same time, at a neutral temperature (32-36 ° C), i.e., with a minimum heat transfer, the goldfinch's energy turnover is 1534 feces, in the gray shrike even 1775 feces by 1 m 2 surfaces per day. The turnover of energy and the need for nutrients, and in accordance with this, the cardiac activity and the work of the respiratory apparatus, change depending on external conditions and periodic changes in the internal state of the body. In males, energy consumption increases during the mating period, in females - during the laying of eggs. The increase in energy consumption is associated with the molting period.

A decrease in energy turnover is observed in incubating birds, which can be considered as an adaptation to a long and motionless stay at the nest.

A decrease in external temperature below known limits causes an increase in energy expenditure to maintain body temperature. For example, a drop in external temperature from 32.6 to 9.8 ° causes a threefold increase in oxygen consumption in a sparrow. To conserve heat, small birds have to expend more energy than large ones (the size of the body surface grows in a square, and the volume in a cube, therefore, in large birds, the ratio of body surface to volume is more advantageous). Small birds, with a significant decrease in temperature, spend more than half of the energy received from nutrition on thermoregulation of the body.

In winter, due to the cold snap and the shortening of the day, critical moments come for birds, and with a strong decrease in temperature, death from exhaustion can occur: the onset of darkness stops feeding, and the bird cannot receive sufficient energy sources.

Plumage and its seasonal changes are essential for thermoregulation of birds (Fig. 10). When molting in autumn, many species show an increase in the downy part of the feather or (with a double molt per year) an increase in the number of feathers compared to the warm season. Geographic forms (subspecies) living in the north differ from their southern relatives in thicker and more lush plumage (three-toed woodpeckers, great spotted woodpeckers, chicks, gyrfalcons). Of great importance for northern birds is the white color of their plumage, in which air bubbles are formed, creating a heat-insulating layer. The value of the feather for keeping warm is clear in itself, but a concrete idea of ​​this is best seen from the experience of Giaia (1929): in the great gray shrike, when the temperature dropped from 28 to 0.6 °, energy consumption increased by 50%, but when the bird was plucked, the same temperature difference caused a threefold increase in energy consumption, that is, by 200%. Other adaptations to cold temperatures: the deposition of subcutaneous fat (especially in aquatic birds), the work of air sacs (retaining the heated air in themselves), a slight increase in the size of birds in northern forms of the same species compared to southern ones, and finally, a relative increase in the size of the heart ...

Fasting causes the temperature of birds to drop. Generally speaking, in those species that have a higher body temperature and higher oxygen demand and are more mobile, the need for food is higher and its absorption is faster. Opposite rates indicate less need for food. Therefore, for example, songbirds chicks die within a few hours after the start of fasting, while large species can live without food for about a month ( White Owl- 24 days, white-tailed eagle - 45 days, golden eagle - 21 days, domestic chickens - 26-31 days). Weight loss in this case can reach 30-40%.

The water requirement of birds is relatively low. This is explained by the insignificance of skin evaporation, as well as by the fact that water is absorbed from the urine by the bird's body back while urine is in the upper part of the cloaca. For this reason, many carnivorous and frugivorous species do not drink at all.

The digestive process in birds is very fast and energetic. At the same time, meat and fruits are digested and absorbed faster, seeds are more slowly. A bird can eat a lot per day, and the maximum in this case often greatly exceeds the required minimum. Small owls (house owls) digest a mouse in 4 hours, a gray shrike - in 3 hours; watery berries in passerines pass through the intestines in 8-10 minutes, grains in chicken - in 12-24 hours. Insectivorous birds fill their stomachs five to six times a day, granivores twice. Predators eat once or twice a day. Small birds eat about 1/4 of their weight per day of dry nutrients, large birds - much less (about 1/10) - Chicks eat more. Accurate observations have established that swallows, tits, starlings and other small birds fly up to the nest with food hundreds of times a day while feeding chicks. So, the great tit brings food 350-390 times, the nuthatch - 370-380 times, the redstart - 220-240 times, the great spotted woodpecker - 300 times, and the American wren even 600 times. At the same time, the weight gain in chicks per day is 20-60% of the initial weight. In the first seven to eight days, the weight of passerine chicks increases 5-6 times. It is therefore clear that the chick eats more food per day than it weighs itself. This circumstance determines the enormous importance of insectivorous birds in the life of nature and in the economy of man. With a high growth rate of birds and a rather significant number of eggs in clutches (which, moreover, in many species it is normal for two per year, and in some even three), one pair of passerine birds has to feed on average 10-15 juveniles per year.

Finally, comparatively recently, another remarkable biological property of birds has been established: an abundance of food and favorable feeding conditions cause increased reproduction in them. Thus, in many species, in years with favorable nutritional conditions, the number of eggs in a clutch is greater than in less favorable years. Sometimes, in the years "fruitful" with fodder, additional clutches appear in birds. On the contrary, in years unfavorable in terms of feeding conditions, the intensity of reproduction decreases (the number of eggs in a clutch is less), and mortality among young birds becomes very high.

There is one more feature that deserves attention. With an abundance of food, birds eat more. For example, according to observations made in Western Europe, in the "mouse" years, one buzzard eats up to 14 mice and voles daily, and in ordinary middle years - up to 5 pieces, the kestrel eats 9 and 2 mice, respectively, long-eared owls - 12 and 4, etc. It should be noted that one vole, according to the estimates of our ecologists, destroys up to 2 Kg grain per year.

Finally, the abundant appearance of some kind of food sometimes leads to the fact that those species of birds that usually neglect this kind of food begin to eat it. The results of observations by A.N.Formozov, made by him in 1936 in North-West Kazakhstan, are interesting: when a large number of locusts appeared, even ducks began to feed on them.

Thus, it can be said that feeding conditions determine many aspects of the life of birds, and in the case of mass reproduction of one or another bird feeding object, it attracts special attention from their side. Consequently, there is a certain kind of natural regulation of the number of massively multiplied animals. It is well known that the appearance of a large number of harmful insects anywhere usually attracts birds. In such cases, the usefulness of insectivorous birds is especially evident. When, for example, in 1893-1895. In the Volga region, the forest pest, the gypsy moth, multiplied strongly, then local observers noted an unusual raid of cuckoos. Reproduction of pests of field cultivation - click beetles attracts rooks, which dig out of the ground and eat the larvae of these beetles, the so-called wireworms. It is estimated that over 8,000 wireworms are eaten by the rook every year. There are observations of how a rook flock in one day completely cleared of these pests an area of ​​6 ha... Breeding of locusts causes increased reproduction and accumulation of various starlings, in particular pink ones. The wandering locust is followed by a wide variety of bird species. Reproduction of mice causes increased activity in the fields of birds of prey - owls, buzzards, small falcons. Wandering lemmings in the tundra and forest-tundra are followed by numerous snowy owls, great gulls and skuas, Upland Buzzards and even peregrine falcons.

The food of many bird species consists of animals that have a negative value for the human economy. These are insects and small mammals, primarily rodents. Reproduction of both goes and can go very quickly. And in the fight against these pests lies the main positive value of birds for the economy. Hunting and poultry birds bring direct benefits to humans, but their value, in contrast to the still widespread opinion, is small in comparison with the benefits that birds bring by exterminating voles, mice, harmful insects, their eggs and larvae. There is no doubt that from an economic point of view, it is this aspect of bird activity that seems to be the most important and significant.

The importance of pest hazards to agriculture should not be understated in any way. If in our time - the time of high technology - they cannot bring the situation to a catastrophe, they nevertheless cause very serious damage. In pre-revolutionary Russia, losses from pests in field cultivation were determined (of course, with a certain approximation) at 900 million rubles. per year, losses of forestry - 300 million rubles, losses of gardening and horticulture - 90 million rubles. In the United States of America, agricultural losses from animal pests in 1921 were estimated at a billion dollars, and the benefits from the extermination of insects by birds were estimated at 444 million dollars; consequently, the birds have reduced the damage by more than one third in relative terms and by an enormous absolute value. All these calculations, of course, are approximate, but they give an idea of ​​the scale and general significance of this phenomenon.

One more consideration is essential. Of the known bird species, the vast majority belong to the order of passerines, which unites, with rare exceptions, insectivorous birds, or birds that feed their chicks with insects. In addition, the number of individuals of these small and medium-sized species is immeasurably greater than the number of individuals of large species, so it would not be an exaggeration to believe that insectivorous birds make up about 90% of the total number of individuals living at the present time.

If so, then we can, perhaps, agree with one American author who expressed the idea that "if all the birds were destroyed, then Agriculture in the United States would be impossible. "

One should not imagine the matter in such a way that birds by themselves can destroy pests during their mass reproduction, but their role in the extermination of rodents and insects in "normal" years is very great and can be characterized as "control" over the reproduction of pests, as a very significant tool for keeping the number of pests low.

Other aspects of bird activity related to nutrition are also not indifferent to humans. Many granivorous birds contribute to the spread of seeds (the latter sometimes remain viable even after passing through the intestines of the bird), in southern countries, many species actively contribute to pollination of plants. Birds of prey hunting other birds and animals play a well-known positive role as a selection tool. A known number of predators contribute to maintaining the health of the species that are their prey, since they primarily prey on sick or weak specimens. Carrion birds have some health benefits.

The food-related traits of birds that are negative from the point of view of human economic interests can be reduced in general terms to the extermination of useful wild animals and wild plants, to competition with more useful species of animals, to harm to cultivated plants, to eating domestic animals. It should be borne in mind that we have no reason to say that this or that bird should be considered absolutely useful or absolutely harmful. Birds do not bring any benefit or harm "in general". Therefore, the question of absolute protection or absolute extermination of any species of birds cannot be raised. A bird, like any other animal, can be useful and harmful only under certain conditions and at a certain time. The situation changes - it changes and economic value birds. Starlings, for example, which benefit from insect control in spring and summer, in some areas during migration and wintering can be definitely harmful to orchards, and more recently in Tunisia, starlings were fought with the massive use of explosives. Ravens harm by destroying the nests of useful birds, in particular waterfowl, but at the same time they exterminate insects, mice and voles. Great spotted woodpecker feeds on insects harmful to the forest, but at the same time destroys a certain number of tree seeds, and sometimes harms the trees themselves (so that sometimes in places, as, for example, in Buzuluk pine forest, harm from the great spotted woodpecker, which interferes with the normal renewal of pine trees , more than good). The sparrow eats berries, displaces beneficial insectivorous birds from their nesting sites, but also feeds its chicks with insects. The peregrine falcon feeds on waterfowl and other useful birds, but at the same time, in the tundra near its nests, the foxes leave the nests of other birds alone, as the falcon vigorously attacks the foxes and drives them out of the vicinity of its nest, thereby providing significant assistance to the entire surrounding bird population ... The goshawk feeds on useful birds, but promotes natural selection and is rightly valued in some places as an excellent hunting bird. We will not touch upon here a very important issue of the aesthetic significance of birds.

It is useful to emphasize that in the fauna of the USSR, numbering more than 700 species of birds, at least less than a dozen species are significantly harmful. Borrowed from Western European owners of hunting grounds and their gamekeepers and, unfortunately, the firmly rooted and widespread opinion about the "harm" of birds of prey must be decisively rejected. The vast majority of predators benefit from the extermination of rodents and insects; others, for example, large falcons - peregrine falcons, gyrfalcons, although they hunt mainly for birds, are rare, and besides, they live in any noticeable number in areas (north) where wild resources are still underutilized by humans. They are in no way competitors of the latter, and at the same time serve as one of the best adornments of our nature; and the reproduction of birds of prey is going on at a relatively slow pace. This does not mean that one should not fight with predators that are in the habit of catching pigeons, poultry, or with a hawk that accelerates the current of black grouse in an organized hunting economy, etc. Feeding conditions are reflected in the geographical and stationary distribution of birds. This is especially true for those species that are stenophages, that is, highly specialized in nutrition.

The African vulture eagle is found only where the type of palm tree that it feeds on grows. Many birds that feed on certain plants or have a certain type of plant dominate the diet are found only where these plants are present. So, for example, the Scottish graus is closely related in its distribution with wild rosemary, crossbills - with certain types of conifers, honey suckers, hummingbirds, etc. - with the presence of those plants whose nectar they feed on.

Omnivorous birds, in fact, are few: ravens are an example of them. In general, each species of bird is characterized by a certain specialization both in the choice of food and in the methods of obtaining it. Unfortunately, these questions have not been sufficiently studied yet. Meanwhile, some certain substances, absorbed by birds even in small quantities and occasionally, are, apparently, very important for the normal functioning of the bird's body. For example, young birds of prey that do not receive bones develop rickets and the normal course of molting is disrupted. For grouse, it is necessary from time to time to swallow needles, which are probably used to cleanse the stomach of worms.

Changes in external conditions that determine feeding conditions are of great importance for birds. These changes are especially pronounced in those regions where climatic changes in the seasons are significant or where various kinds of meteorological conditions (snow cover, humidity, temperature, etc.) fluctuate greatly. The influence of temperature on the body's need for food and the effect of light on the ability to satisfy this need has already been said above. Snow cover is also important for land-feeding species. Therefore, for example, many granivorous birds winter in Mongolia, where winters are very harsh, but there is little snow. On the other hand, for example, in Lapland, beyond the Arctic Circle, you can meet a rather diverse composition of small passerines in winter: titmouse, great tit, pika, etc. These birds get food from trees and are less dependent on snow cover. For the same reason, birds that forage from cracks and other shelters or on vertical tree trunks in the bark, etc., for example, wrens, nuthatches and the already mentioned pikas, do not fly away for the winter, but remain in the cold and temperate zones at home. Even in the conditions of the Arctic polar night, birds winter, if only they had the opportunity to get their own food. For example, off the coast of Greenland, the polar guillemot hibernates near polynyas and openings at 77 ° and even 78 ° 30 "north latitude, near Spitsbergen - even at 80 ° north latitude. In the tropics and subtropics, the main climatic cause of changes in bird feeding conditions is the onset of the dry season. ...

The disappearance of insects, the decrease in the number of insects, periodic changes in the life of plants - all these factors determine the feeding regime of birds and, accordingly, affect their distribution.

While in some species these changes cause movement, in others they are associated with seasonal changes in the diet. Ptarmigan, for example, feed mainly on berries and insects in summer, berries in autumn, and willow shoots in winter. The raven in Northern Siberia is omnivorous in summer, and in winter it feeds mainly on pies. In summer, starlings feed mainly on insects, in autumn and during wintering, in addition, on fruits and berries. There are many such examples.

Harvest and poor harvest of feed greatly affect the life of birds. Periodic quantitative fluctuations in the animal population and in the vegetation cover cause periodic fluctuations in the conditions of existence of birds, for which certain animals and plants serve as food. These phenomena include the harvest and poor harvest of fruits and berries, the abundance or paucity of insects, the mass reproduction or extinction of rodents, etc. The mass appearance of food objects also causes the mass appearance of the corresponding bird species, and vice versa. For example, with a poor harvest of mountain ash from Northern Europe, waxwings migrate in masses, with a failure of cones - crossbills, walnuts, etc. More or less prolonged changes in nutritional conditions sometimes cause changes in the boundaries of the distribution area. So, the house sparrow gradually settled, following the man, but the replacement of horses with cars caused a decrease in the number of sparrows at the northern border of its distribution - in Scandinavia and a strong decrease in its number in North American cities.

The influence of nutritional conditions on reproduction and mortality has already been discussed. Here are just some of the numbers. In Lapland, in the "lemming" years, the hawk owl has 11-13 eggs, the great gray owl has 7-9 eggs, the eagle owl has up to 6 eggs, the long-eared owl has 7-9 eggs, and the white owl has 11-12 eggs. Even the Lapland Gyrfalcon had clutches of 7-9 eggs in an exceptionally rich year with lemmings near the town of Kautokeino in northeastern Norway. The second clutches in years rich in forage in those species that usually have only one clutch have already been mentioned.

On the other hand, in lean years, with a decrease in the number of rodents, predators feeding on them have a smaller number of eggs in clutches, and mortality among chicks is higher. Apparently, the result of poor feeding conditions can explain the phenomenon of cannibalism among the chicks of many predatory species - hawks, eagles and other birds, when the youngest of the chicks becomes the prey of the older ones.

The influence of feeding conditions on the reproduction of birds in the north is especially noticeable, where, in connection with this, periodic non-nesting is observed. Such fluctuations in numbers and "refusals" from nesting have been established in the Arctic for birds of prey and some waterfowl, and in other latitudes - for many chickens (hazel grouses, partridges, quails, pheasants, etc.).

The feeding conditions undoubtedly underlie the occurrence of bird flights, although, of course, the modern picture of this phenomenon is very complex and is determined, apparently, by a whole set of external and internal causes. We will return to the question of flights below.

We turn to the description of the cycle of phenomena in the life of birds, related with reproduction.

The reproductive system of birds is characterized by the fact that the period of its activity in the vast majority of species is limited to a strictly defined time of the year, and at rest the size of the gonads is literally ten times smaller than during the period of activity.

The structure of the female reproductive system is characterized by its asymmetry: the right ovary, as a rule, is absent, the right oviduct is always absent. During the breeding period, the volume of the ovary increases greatly, and since the eggs in it are at different stages of development, the entire organ takes on a sort of aciniform shape. At the end of ovary laying, the ovary rapidly decreases, and its size reaches the size of the resting ovary even at the time when the bird is incubating. Likewise, in connection with the onset of the breeding season, the oviduct also increases in volume. For example, in a domestic chicken, the oviduct during the resting period has about 180 mm in length and 1.5 mm in the lumen, during the laying period - about 800 mm in length and about 10 mm in the lumen. All parts of the oviduct at this time become more isolated than at other times of the year.

After the laying period, the oviduct collapses, the tubules of its glands are reduced, its lumen remains uneven and expanded in places. In a bird that did not lay eggs, the oviduct looks like a smooth and throughout a thin tubule. These differences in the state of the oviduct can serve as a reliable indicator for determining the age of autumn and spring birds.

A very characteristic adaptation to the breeding of offspring in birds is the development of the so-called nesting(hatching) stains(fig. 11). The presence of these spots makes it easier to heat the masonry. The skin in the area of ​​hen spots is distinguished by a particular looseness of the connective tissue; the fat layer usually disappears here; down, and sometimes feathers and their rudiments fall out; cutaneous muscle fibers are reduced; at the same time, the supply of blood to these places is enhanced. A fully developed hen spot is an area of ​​bare and slightly inflamed skin. Each bird species is characterized by a certain arrangement of brood spots; they are sometimes paired, sometimes unpaired. Passerines, petrels, guillemots have one spot, pheasants, waders, gulls, and carnivores - two abdominal and one pectoral. The size of the hen spots is in a certain correspondence with the size of the clutch. Geese and ducks have no hen spots; they, however, develop a special long fluff during the laying of eggs, which is pulled out by the bird; This fluff surrounds the eggs in the nest with this fluff and serves as an excellent means of protecting them from chilling. Boobies do not have hen spots, but they warm their eggs, covering them from above with their webbed paws; guillemots and penguins put their paws under the eggs. These birds, apparently, have special arterio-venous anastomoses in their paws, which provide increased blood supply to these parts of the body. In addition, penguins have a special leathery protrusion, or pocket, near the cloaca, which is arbitrarily stretchable and allows the incubating bird to cover the egg with its skin.

In addition to the changes just mentioned in the body of birds in connection with the breeding period, there are others, in particular, many species develop a bright mating outfit. Difference in appearance between males and females is designated as sexual dimorphism.

External signs of sexual dimorphism cannot be put into any general scheme. Penguins, petrels, copepods, grebes, loons, swifters, swifts, many bee-eaters and kingfishers do not differ between the sexes in either color or size. Males and females of small passerines, most carnivores, owls, waders, gulls, guillemots, shepherds and other birds differ only in size.

In other species, males differ more or less sharply from females in color. Usually, the color of the male is brighter in those species in which the male does not take part in caring for the offspring. In these cases (ducks, many chickens), the females often have a pronounced protective coloration. In the same species, in which males take care of the offspring (colored snipe, wader phalaropes, some kingfishers, three-fingered birds, etc.), the females are somewhat brighter than the males.

Differences in color usually appear after reaching puberty, but sometimes even earlier (woodpeckers, passerines, etc.). In many forms that have two molts a year, color dimorphism is noticeable only at certain times of the year, namely during the breeding season.

The brightness of the color of males is especially characteristic of northern ducks (but not geese), many chickens (pheasants, turachi, wood grouses, black grouses), many passerines (the so-called birds of paradise, orioles, finches, redstarts, etc.). In related groups, differences in sex color are generally similar even in different species (in Orioles, males are bright yellow or red, females are dull greenish with a longitudinally speckled ventral side of the body; many finches have red colors in males that are absent in females, for example, beetles, crossbills, bullfinches, especially lentils, etc.). Sometimes females develop a coloration similar to the coloration of males (the so-called cockfeather coloration in grouse, in some passerines - redstart, shrike, etc.). In addition, with age, females with functioning gonads sometimes exhibit the appearance of features similar to the color of the male; this happens, for example, in birds of prey (merlin, etc.).

Sexual differences in color are expressed not only in the color of the plumage, but also in the color of other parts of the body (beak, iris, naked parts of the skin, even the tongue). In cuckoos, the color of males is of the same type (gray), females are dimorphic (except for the gray color, there is also a red one).

Sexual differences are expressed, in addition, in the presence of outgrowths and appendages of the skin on the head (for example, in chickens), in the development of individual feathers (crests, long tail coverts in peacocks, feathers on the wing and tail of birds of paradise, long tail feathers in pheasants, etc. etc.), in the proportions, sizes and shape of individual parts of the body, in the structure of internal organs (the vocal apparatus of many species, the throat sac of the male bustard, etc.), in total size.

Male chickens develop spurs on their legs, males and females of many species have different beak sizes (hornbills, ducks, scooters, some passerines, etc.).

As a rule, males are larger than females. This is especially pronounced in chickens and bustards. Other groups of females have more males. This is observed in those species in which males take care of the offspring (among phalaropes, colored snipe from waders, three-fingered birds, tinamou, some cuckoos, kiwis and cassowaries). A large size of females, however, is also found in those species in which the main part of care for the offspring lies with the females (in most diurnal predators, owls, many waders).

We now turn to the description of bird reproduction itself.

With the onset of spring, when revival begins everywhere in nature, the behavior of birds also changes. Migratory species leave wintering grounds and go to their distant homeland. Wandering birds that do not fly also begin to approach their nesting sites. Sedentary species appear at the nests. Not in all places and not in all bird species this spring revival occurs simultaneously. The farther south the territory, the earlier, of course, the spring revival of nature begins there.

For each species of birds, spring revival is associated with the onset of special, favorable circumstances for this species. Sometimes it is even difficult to understand why one bird arrives early to the nesting site, and the other late. The bearded man, or lamb, living high in the mountains, begins to nest in the Caucasus and Central Asia in February, when everything is covered with snow; this early start to nesting is due to the slow development of chicks. They appear in April, by July they only reach the size of adults and until September they still remain with their parents and use their help. Consequently, the first months of life of young bearded vultures fall at the most favorable time in terms of temperature, nutritional conditions, etc. If the bearded vultures began to nest later, their nesting would end only in winter. For the same reasons, the gyrfalcon nesting in our far north sit on eggs among the snow in early spring, otherwise they would not have had time to hatch the young before the harsh autumn weather.

The desert saxaul jay begins to nest in the Karakum desert very early, even before the appearance of a large number of insects and before the development of vegetation. This early period enables the desert jay to reared its children in relative safety. Its nest is easily accessible for the main enemies of the birds of the Central Asian deserts - various snakes and monitor lizards, but early nesting allows the chicks of the jay to learn to fly before the revitalization of the reptiles begins with the onset of warmth.

The last example is a swift and a swallow. Both birds fly excellently and feed on insects, but the swift arrives late and flies away early, and the swallow stays with us much longer. The late arrival of the swift is due to the fact that favorable conditions for feeding and rearing chicks for it come later than for the swallow. The difference in the structure of the eyes allows the swallow to see well in front of itself and on the sides, while the swift sees well only in front of itself. Therefore, the swift can only catch flying insects, and the swallow, in addition, can peck out or grab on the fly those insects that sit on buildings, trees, etc. quantity can be found earlier and later. That is why the swift appears later than the swallow and flies away earlier.

Many birds mate for life; this includes large predators, owls, herons, storks, etc. Others form seasonal pairs (songbirds). There are, however, those species which do not form pairs at all and in which all the care for the offspring falls to the lot of sex alone. Most often, this sex is the female. This is how the summer life passes for most of our chicken birds - wood grouse, black grouse, pheasant, as well as turukhtan sandpiper. However, among the waders living in the north and among the three-fingered waders found in the USSR in the Far East, the male takes care of the brood. In the aforementioned chickens and turukhtans, males are colored brighter than females. The opposite is true for phalaropes and three-feathers: their female is larger in height and more elegantly feathered than the male. Birds that form pairs are called monogamous, not forming a pair - polygamous.

The behavior of birds during the mating season, which falls, as a rule, in the spring months and early summer, is distinguished by a number of features. Many birds also change their appearance at this time. A number of birds change part of their plumage by spring and put on a mating outfit, which usually differs from the autumn one in bright colors.

In some species, males lick, that is, they take special, from a distance, striking postures, emit special cries. Such mating is especially well expressed in chickens - black grouse, wood grouse, ptarmigan, and some waders. Other birds in the spring make peculiar movements in the air - they soar high up, fall down, and soar again, uttering loud cries at the same time. Such a mating flight is performed, for example, by birds of prey; the spring draft of woodcocks and the spring "bleating" of snipe have the same meaning. In small passerine birds, males sing during the mating season, enlivening with their singing both inhospitable deserts, and severe tundra, and human settlements. The same phenomena include the spring "dances" of cranes, and the crowing of cuckoos, and the spring drumming of woodpeckers, and the cooing of pigeons.

Each species of bird is characterized by a certain and different from other species behavior in spring - voice, posture, etc. Each songbird - nightingale, starling, chaffinch - sings in its own way. Thus, mating refers only to other individuals of the same species and serves as a specific signal for them. These signals are by no means always directed to individuals of the opposite sex. For a long time, it was thought that the singing of male birds refers only to females and attracts them. In fact, this is not the case. The importance of singing is primarily to show other males of the same species and potential competitors that the breeding area is occupied. Birds in the spring, as you know, jealously guard their places (nesting sites) and drive out of them all other individuals of the same species. The nesting area is especially jealously protected in the most "crucial" periods, immediately before laying eggs in the nest and during incubation.

Interesting observations have been made in England. A weasel appeared near the nest of the reed bunting. The male and female bunting began to fly around her screaming and tried to drive her away. Another reed oatmeal flew up to the noise, and the disturbed couple, abandoning the weasel, began to drive the oatmeal. This scene was repeated three times in a row.

The significance of the leaking also lies in the fact that it expresses and intensifies the excitement of the leaking bird and individuals of the opposite sex. This is the only meaning of mating in those species that do not form mating pairs (capercaillie, black grouse, turukhtans).

The center of the bird's nesting site is nest- the place where the female lays eggs. However, not all birds build their nests. In the north of the USSR, for example, on the islands in the White Sea, on Novaya Zemlya, as well as on the Chukotka Peninsula, Kamchatka, on the Commander Islands, seabirds (guillemots, guillemots, auk) nest in huge numbers, forming thousands of clusters, the so-called "bird colonies ". But they do not actually suit the nests, and each female lays her egg right on the rock ledge. They do not arrange nests with a nightjar and an avdotka: they lay eggs directly on the ground. Some birds only clear a place for laying and sometimes still make a simple bedding of dry grass, moss, feathers, etc. This is how pheasants, wood grouses, hazel grouses, partridges, black grouse, waders, most owls, some predators, and also those birds do , which hatch chicks in hollows, are woodpeckers, whirligig. Most birds, however, do nest, and each species has a specific nesting style and material choices. Young birds, who have never seen how a nest is built, arrange it in the same way as their parents.

Most often, nests are made from twigs, grass or moss; these nests are either folded or woven, moreover, special ones are often used to fasten them and lining Additional materials... Blackbirds weave a nest from stalks and coat it with clay. The finch makes a nest of moss, disguising it with lichen. Remez tit skillfully weaves a nest of wool in the shape of a purse with a long side corridor. Small birds nesting on the ground (larks, wagtails) make nests from grass or line a depression in the ground with grass.

Birds of medium and large size build nests from large twigs and branches. Some birds have several nests, in one of which they nest, while others serve as spare ones. For large birds of prey (eagles, eagles), the nest serves for many years in a row and, as a result of amendments and superstructures, over the years turns into a huge structure up to 2 m in height and in diameter. In the end, such nests usually fall to the ground in storms, since the bitches that support them cannot withstand their weight.

The inner part of the nest is usually deepened, and the edges are raised; deepened part of the nest - tray, or tray, serves for placing eggs and chicks.

Some birds make stucco nests. Flamingos make nests from silt in shallow water. Rocky nuthatches living in the mountains build nests from clay. The barn swallow makes a saucer-shaped nest of clay and mud glued together with saliva under the roofs. The city swallow, or funnel, arranges a nest closed on top of a roof from the same materials.

Some birds nest in burrows. In kingfishers, a zigzag course breaks through between the roots in the earthen cliffs on the banks of the rivers; this passage leads to a cave, the bottom of which is lined with fish scales. Barn swallows nest in colonies along river banks. Their nests are difficult to access, since a narrow passage leads to them, sometimes reaching a length of 3 m... Pink starlings, sheath ducks, Rollers and Bee-eats nest in minks.

Finally, the runner sandpiper, found along the sandy shoals of rivers in Turkmenistan, simply buries its eggs in the hot sand. This nesting method is somewhat reminiscent of the actions of weed chickens, or bigfoots, living in Australia and on the islands lying southeast of Asia. Weed chickens lay their eggs in huge heaps of sand or rotting plants, these heaps sometimes reach 1.5 m in height and 7-8 m in a circle. The eggs are well protected from cooling here, and the embryo's own heat is enough for its development.

A place for a nest for those birds that actively defend their nesting site, that is, in passerines, nightjars, some waders, etc., is sought by the male, who, moreover, usually returns from wintering or migrations earlier than the female.

The number of eggs in a clutch of each bird species varies within certain limits. More or less of them depends on different reasons. In many species, in years favorable in temperature conditions, and especially in terms of feeding, the number of eggs in a clutch is greater than in bad years. This has been established for many owls, chickens, etc. In especially unfavorable years, such birds do not nest at all. The age of the bird is also of some importance. In predators, ravens, old females apparently lay fewer eggs than young ones. In chickens, on the contrary: in the first year, females lay fewer eggs; young females of some passerines, such as starlings, also lay fewer eggs. Due to different nesting conditions in the same bird species, the number of eggs in a clutch in the north and in the temperate zone is greater than in the south. For example, in an ordinary heater in Greenland, the number of eggs in a clutch is 7-8, in the European part of our country - 6, and in the Sahara - 5. A large number of eggs in a clutch in the north is, as it were, insurance against unfavorable climatic conditions, and also corresponds to large opportunities for feeding chicks in the north (long day and almost round-the-clock activity of insects).

Some predators always have one egg in a clutch (for example, the snake-eater), the sandpiper, the tube-nosed ones, and many guillemots. Nightjars, pigeons, cranes, flamingos, pelicans, gulls, terns have 2 eggs per clutch. Sandpipers and three-tails have the usual and maximum number of eggs in a clutch. Small passerines have 5 eggs in a clutch, often 4, 6, and 7; it happens even more, for example, in the great tit up to 15, in the long-tailed tit up to 16. Of the duck, the greatest number of eggs in the teal is 16, of the hens in the gray partridge - 25. The usual number of eggs in the clutch of hens and duck is 8-10.

The color and shape of bird eggs are very diverse (Table 1, 2). Some, such as owls, have almost round eggs, while others are elongated. One end of the egg is usually wide, the other is narrower. The narrowing of one end of the egg and the expansion of the other are especially pronounced in various guillemots nesting in colonies in the north. In those birds that lay eggs in closed nests, in hollows and holes, or cover eggs, the color of the shell is white. White eggs in owls, kingfishers, rolling rollers, woodpeckers, and many passerines. In birds nesting in open nests, and even more so on the ground, eggs are variegated, and their color is very similar to the color of the landscape surrounding the clutch. You can go two or three steps to a clutch of some sandpiper or partridge lying on the ground and not notice it. The thickness of the shell varies greatly. Birds nesting on the ground have relatively thickest shells; this is understandable, since their eggs are at greater risk (of course, this refers to the relative thickness of the shell in accordance with the size of the egg). Of our birds, the thickest shells are related to chicken birds turachi.

Table 2. Bird eggs: 1-8 - common cuckoo(1, 3, 5, 7) and small passerines - "host" birds (2 - blackbird, warbler, 4 - red-eared bunting, 6 - common redstart, 8 - garden warbler); 9 - small cuckoo; 10 - short-tailed warbler; 11 - common oatmeal; 12 - black-headed warbler; 13 - oatmeal; 14 - polar bunting; 15 - snow buntings; 16 - lark; 17 - white wagtail; 18 - grosbeak; 19 - common starling; 20 - fieldfare; 21 - mistresses; 22, 23 - shriek; 24 - thick-billed warbler; 25 - warbler; 26 - blue stone thrush; 27 - song thrush; 28 - common pemez; 29 - great tit; 30 - jackdaws; 31 - crows; 32 - crow; 33 - magpies; 34 - jays; 35 - common pika; 36 - yellow-headed beetle; 37 - finch; 38 - barn swallow; 39 - wren; 40 - field sparrow; 41 - deaf cuckoo; 42 - house sparrow; 43, 44 - forest pipit; 45 - ordinary tap dance; 46 - meadow minting; 47 - willow warblers; 48 - shade-forging warblers; 49 - common nightingale; 50 - saxaul jay; 51 - rocky nuthatch; 52 - common lentils; 53 - goldfinches; 54 - Lesser Whitethroats; 55 - gray flycatcher; 56 - long-tailed flycatcher; 57 - broad-tailed warbler; 58 - bullfinch; 59 - waxwing; 60 - pike-hole; 61 - spruce crossbill; 62 - African black-headed oriole; 63 - common oriole; 64 - woodcock; 65 - great curlew; 66 - brown-winged plover; 67 - common turtle dove; 68 - blue dove; 69 - sandpiper; 70 - wood snipe; 71 - blue magpie; 72 - lapwing; 73 - small plover; 74 - krustana; 75 - blackies

The size of the eggs depends on a number of reasons. Small birds, in comparison with their own weight, lay rather large eggs, large birds - small ones. The more eggs there are in the clutch, the smaller the relative size of an individual egg. Finally, those birds whose chicks leave the nest well developed and capable of independent movement and foraging, lay relatively larger eggs than those whose chicks are born helpless. The cuckoo lays very small eggs, this is probably due to the fact that she does not incubate them herself, but throws small birds into the nests. Both the cuckoo and the snipe weigh about 100 G but the snipe egg weighs about 17 G, cuckoo egg - only about 3 G.

Interesting data on the ratio of the body weight of a bird, the weight of an individual egg and the weight of the entire clutch.

In some birds, the clutch weight even exceeds the body weight of an adult bird: in a pod with a clutch of 12 eggs, it is 125% of the bird's weight, in a carrier sandpiper - 117%, in a kinglet with a clutch of 11 eggs - 120%, in a gogol duck with a clutch of 12 eggs - 110%.

In incubation of eggs, sometimes both parents participate - a male and a female (for example, in many predators), sometimes only a female. The latter refers to those species in which the male and female already live separately during incubation, such as capercaillie, black grouse, pheasants, ducks. Both sexes usually incubate when their coloration is similar, however, there are exceptions. In most passerines, only the female incubates. Finally, in three-fingers and phalaropes, only males take care of the offspring.

Incubation is a very dangerous time in the life of birds. A bird sitting on a nest can easily be attacked by various enemies. Birds nesting on the ground can be especially easily affected. Therefore, the females, on whom most of the worries about the laying and about the chicks, nevertheless fall, in many species are painted to match the color of the surrounding area. Females of ptarmigan, pheasant, little bustard sitting on eggs completely merge with the surrounding soil and vegetation. It should be borne in mind that the incubating bird is less careful and, especially at the end of incubation, flies from the nest very reluctantly - only at the very last minute, so that the value of such a color that is in harmony with the landscape is very great. The incubating bird feeds less than usual, especially in those cases when the male lives separately at this time. Therefore, the incubating bird usually loses weight and loses much weight.

The duration of incubation in individual bird species is very different. It depends on the temperature of the environment, the body and the length of breaks when the brooding bird leaves the nest, partly on the size of the egg compared to the size of the bird. A longer period of incubation occurs in those species that nest closed - in burrows, hollows, etc. Small passerines incubate for an average of about 15 days. Large predators sit on eggs for a very long time - about one and a half months.

Birds begin to incubate in different ways, some immediately after laying the first egg (predators, owls, storks, gulls, swifts, hoopoes, loons, toadstools, from passerines - crows and crossbills). In such birds, there are great differences in the development of individual chicks, and in the "mouse" years in the nest of a snowy owl in the tundra one can find an egg, a newly hatched chick and large owls donning a transitional outfit. Chickens, ducks, geese and most passerines incubate the clutch only after all eggs have been laid and their chicks develop more evenly. Finally, there are such birds in which hatching begins after more than half of the eggs have been laid (woodpeckers and shepherdesses). When one egg is removed from the clutch, some species of birds (for example, gulls, skuas, waders) supplement the clutch. When all clutches die, many birds make a second, additional clutch, unless incubation has gone too far. The use of chickens in poultry farming is based on this property of birds (egg production of domestic chickens reaches 350 eggs per year). By taking eggs from a bird, one can force it to lay very intensively (in such experiments, the spinner was forced to lay up to 62 eggs).

Many small birds normally have two or even three clutches in the summer. Additional and second clutches, if they occur by the end of summer, contain fewer eggs than the first clutches. But in those birds in which the first clutch is very early, when spring is just beginning and the conditions for the growth and rearing of the young are less favorable than for chicks hatching later, there are fewer eggs in the first clutch than in the second (blackbirds, Muscovy tit, larks , common oatmeal).

According to the way the chicks develop, all birds can be divided into two categories: some are called brood, other - chicks(fig. 14).

Chicks of brood birds leave the nest immediately or very shortly after hatching and can move independently. They leave the nest with open eyes and ears, in a well-developed downy outfit. This group includes those birds that keep mainly on the ground or near the water, but not on trees: ducks, geese, shepherdesses, bustards, cranes, loons, grebes, gulls, sandpipers, sand grouses, flamingos, three-fingers.

Young chick birds emerge from the egg with underdeveloped muscles of the limbs, naked or weakly pubescent, often blind and deaf. They do not yet have a constant body temperature, and in this respect they resemble lower vertebrates. These chicks, therefore, are completely helpless and spend the first days or weeks of life in the nest until they develop plumage and they can not move independently. It can be said that the chicks of brood birds emerging from the eggs correspond in their development to the chicks of the period when the latter are ready to fly out of the nest. Chick birds include, for example, passerines, woodpeckers, cuckoos, hoopoes, swifts, pigeons, rakshas, ​​kingfishers, copepods (pelicans and cormorants), as well as carnivores, owls, and tube-nosed birds.

Young chicks have a very characteristic mouth color and its edges - usually bright (yellow or pink).

Brood care in brood and chick birds is also different. The brood adult bird, at which the young are composed (in some species the male, in the majority - the female, less often part of the brood is with the male and part with the female, as is the case with grebes and cranes), leads the brood, protects it, covers it with his body when the weather is unfavorable (cold, rain), searches for and indicates food to the chicks. However, little ducklings immediately begin to find their own food on their own. In some waterfowl, chicks in the first days of life, when tired, sit on the mother's back, and toadstools, when swimming and even diving, keep chicks under their wings.

The relationship between parents and offspring is more complicated in chick birds. In cases when both sexes participate in incubation or when the male feeds the incubating female, both parents feed the chicks together, but the nature of their participation in feeding is not the same. At first, in birds of prey, prey is caught mainly by the male, and the female feeds the chicks, tearing the prey to pieces. When chicks grow up and begin to tear prey themselves, both parents carry food to them. It has already been noted that feeding chicks requires a lot of effort from old birds.

Feeding chicks with food in different species occurs in different ways. Insectivorous birds give food to only one chick upon arrival at the nest (with rare exceptions), meat-eating and granivorous birds - to the entire brood. The sequence and uniformity of feeding of chicks in granivores is ensured by the movement of "well-fed" and "hungry" chicks in the nest. Fed chicks usually move to the edge of the nest and defecate by lifting the tail high; the hungry move in their place in the middle of the tray.

Adult birds cleanse the nest of all impurities (only pigeons and hoopoes do not do this) and heat the chicks, covering them with their bodies. Since overheating is no less dangerous for chicks than cold, the parents shade the nest at hours when the direct rays of the sun fall on the brood; an adult bird stands above the nest and slightly unfolds its wings. Many predators shade their chicks with green tree branches.

In chick birds, chicks usually leave the nest after they have learned to fly.

In different bird species, the timing of chicks in the nest is different. In small passerine birds, the period of stay of the chick in the nest from hatching to emergence is about two weeks or more (in the blue tit 18 days, in the king 18-19 days, in the robin 15 days, in the wren 17 days), i.e. That is, it approximately coincides with the period of incubation. In large species, development is slower and not only absolutely, but also relatively. The raven incubates for 21-22 days, and the chick sits in the nest for 50 days. Red-throated loons incubate for 38-40 days, and the ability to fly occurs only in 60-day-old chicks. Passerines are most likely to develop chicks of nesting forms on the ground (the lark flies out of the nest on the 9th day after hatching, the nightingale on the 11th), while the chicks of nuthatches nesting in the hollows sit in the nest for 25-26 days, the chicks of the great tit - 23 days, starling chicks - 21-22 days. Species nesting in the north also develop rapidly: the Lapland plantain leaves the nest in 10 days.

Parents continue to feed chicks for some time after their departure from the nest. Departure from the nest is also associated with the full development of a plumage of feathers, which replace the downy clothes of the chick.

Chicks reach full growth in the first autumn of life. The vast majority of birds, with the exception of some large species, begin to nest already at the age of about a year, that is, by the following spring. Even those birds nest that by this time are wearing plumage that differs in color from the plumage of adults (for example, a falcon, a hawk). Interestingly, the weight of chicks just before leaving the nest is often greater than the weight of young birds in the following months. This is because exercise on the move and flying alone sometimes cause young birds to lose fat.

How many years do birds live? There is relatively little information about the duration of their life in natural, natural conditions. A well-known idea of ​​the longevity of birds is provided by the results of their tagging and ringing, as well as observations of the life of birds kept in captivity. At the same time, it is necessary to distinguish between the potential life expectancy that is maximum possible from a physiological point of view and the real, average one that exists in nature, where various reasons act that limit the life of the bird: unfavorable weather (meteorological) and forage conditions, the activity of all kinds of predators, and finally, diseases.

Generally speaking, large birds have a longer lifespan than small ones. A definite connection it was not possible to establish between the life span and the characteristics of reproduction (fertility, type of development - chick or brood) in birds. Finally, there are differences in life expectancy in different taxonomic groups of birds. It can be noted that small passerine birds live relatively longer than small mammals.

The English zoologist Flower calculated (1925-1938) the average lifespan of birds living in the London and Cairo Zoological Gardens, and came to the conclusion that within the same order it varies relatively insignificantly. According to his calculations, the average life expectancy in ravens and cockatoo parrots is 20 years, in owls 15 years, in daytime birds of prey 21-24 years, in copepods 20 years, in duck 21 years, in herons 19 years, in waders 10 years , in gulls 17 years old, in ratites 15 years old, in pigeons 12 years old, in chickens 13 years old.

For domestic chickens, life expectancy is noted, of course, as an exception, 24, 25 and even 30 years. (However, signs of aging - a decrease in fertility - are noted in Leghorn laying hens after 3 years of age.)

A few figures about the potential lifespan of captive birds. From the order of passerines for the crow, the age of 60 and even 69 years was noted, of the small passerines for the garden warbler - 24 years, for the blackbird and the robin - 20 years, for the lark - more than 20 years. From the order of owls, owls lived up to 34, 53 and 68 years old. Parrots are also durable: for the red macaw, the age of 64 years is marked, for the cockatoo - more than 56 years, for the parrot, the gray - more than 49 years. For daytime predators, the following data are known: the buffoon eagle lived for 55 years, the condor for 52 and more than 65 years, the golden eagle for 46 years, and according to other, but not very reliable information, for more than 80 years, the griffon vulture for more than 38 years. Of the anseriformes, the Canadian goose lived for more than 33 years, the lesser swan for 24 1/2 years. Of the cranes, the Australian crane lived for 47 years, the gray crane for 43 years, and the antigone crane for 42 years. The African whale heron lived for 36 years. Herring gulls survived to more than 20 years of age, and one even to 49 years. The pink pelican lived to be 51 years old. Some pigeons have lived for about 30 years. Ostriches were milked up to 40, emu up to 28 years.

Other data on the age of birds are obtained from ringing. A few numbers related to The Soviet Union are as follows. The turukhtan, ringed by an adult, was caught at the age of 9, the oystercatcher - at the age of 14, the black-headed gull - at the age of 16, the sea-dove gull - at the age of 20 1/2 and 21 1/2 years, the black gull - at the age of 16, 17 and 18 years old, Arctic tern at the age of 13 and 14 years old, black-throated loon at the age of 17 1/2 and 22 years. Despite the significant mortality of ducks as a result of hunting them, there are known cases when mallards ringed by adults lived up to 18 and 20 years; wide-beaked duck - up to 20 years. The lifespan of the eider is set at 12 years. The ibex heron lived up to 20 years, the bittern - up to 9 years, the stork - up to 11 years. Ringed with chicks, the kites survived to 12 and 15 years old. Harrier harvested at the age of 13. A hooded crow marked with a chick lived up to 14 1/2 years, a starling up to 12 years old, a pink starling up to 11 years old, a thrush warbler up to 8 years old, a black swift even up to 9 years old. In other countries, ringed small passerines were caught at this age: house sparrow - 11 1/2 years, robin - 10 1/2 years, gray flycatcher - 12 1/2 years, killer whale - 9 years. These figures, of course, are not limiting.

However, in a natural setting, the natural mortality of birds significantly limits the life span and they can reach the "limiting" age only as an exception. The mortality of young birds during the first year of life is especially significant. In particular, in passerines, it seems to exceed 50% (naturally, with fluctuations in years and species). For example, in the pied flycatcher, the mortality rate of first-years is noted in 60% of their total number, and in the redstart - even up to 79%. Of the 77 orca chicks ringed in one locality in the GDR, 51 disappeared in the first year, 17 in the second, 6 in the third, 2 in the fourth, and only one survived to the age of five. In American wren, up to 70% of adults and up to 74% of young first-year birds die during the winter.

Similar phenomena take place in other birds. For example, in emperor penguins in harsh Antarctica, the mortality rate of young people in unfavorable years reaches 77%. Of the peregrine falcons ringed in the GDR, 44 were caught at the age of one year, 10 at the age of 2 years, 4 at the age of 3 years, and only 2 at the age of four. Of the 669 banded buzzards caught in the GDR, 465 were caught in the first year of life, 111 in the second, and only 93 were older. In the Wilson storm petrel on Graham Land in Antarctica, up to 65% of chicks die in burrows where these birds nest, mainly due to snow blockages. In the common tern in the first year of life, up to 95% of juveniles die, but the average mortality rate of terns surviving the first year of life at all ages is only 17.2%. At the same time, the average age of birds in a nesting colony (excluding young ones) is 3-5 years.

In aquatic birds, especially colonial ones, the average age is higher than in passerines, and the natural mortality of adults is relatively lower.

Of the other general questions of the biology of birds, which are in a known connection with the phenomena of reproduction, it remains for us to dwell on molting and on flights.

Need molts, i.e., the periodic change of plumage, is explained by the wear and fading of the feather. Under the influence of the sun, moisture, dryness, the color of the feather changes: black becomes brownish, dark brown - pale brown, gray - brownish-gray, etc. the interlocking barbs are partially destroyed. Particularly lightly pigmented or non-pigmented parts of the feather are frayed. These changes, moreover, are more significant in the tail feathers, which are the most critical in flight, - the flywheels and tail feathers. Feathering unfavorably affects the flying properties of the bird.

The most intense molt in adult birds occurs after the end of the breeding season. The alternation of reproduction and molting processes can be partially explained by the fact that both of them require the expenditure of a large amount of energy and therefore can hardly occur in the bird's body at the same time. The normal course of molting requires good nutrition of the body, weakening of nutrition causes a slowdown in the course of molting and irregularities in the structure of the feather (transverse impressions appear on large feathers, going along the fan and making the feather fragile).

While the feather has not yet reached half of its normal length, it grows quickly, and then slows down. Feathers grow more slowly in small birds than in large ones. In a sparrow, the secondary flywheel grows at a rate slightly exceeding 4 mm per day, in the Saker Falcon, the daily increase in flight feathers in the last period of growth is 6-7 mm in a day.

Each species of birds molt at a very specific time and in a specific sequence. Birds belonging to the same family and order usually have the same moulting course, and this is thus one of the systematic features of the groups.

There are well-known general regularities in relation to the change of flight and tail feathers. The tail feathers are replaced either centripetally, that is, from the extreme pair to the middle pair, or centrifugally, that is, from the middle pair to the extreme, or, finally, as is the case with woodpeckers, the molt begins from the pair adjacent to the middle steering feathers, goes to the edge of the tail, and ends with central helmsmen. Secondary flight feathers usually moult concentrically, that is, molt begins from the outermost and inside feathers and ends with middle feathers, or centrifugally. The molt of the primary flight feathers ends with the change of the front (second and first) feathers; in some species, it begins with the middle feathers (from the seventh) and goes to the inner (proximal) edge of the row, that is, first the eighth, ninth, tenth, and then the sixth, fifth, fourth, third, etc. are replaced; in other species, primary flight feathers are replaced in a row - tenth, ninth, etc. ducks for 21-35 days, swans - up to 49 days) loses the ability to fly. In some birds, molt begins with small feathers, in others - with large ones, although in general the change of small and large plumage coincides, but the change of the front primary flight feathers, as the most important feathers during flight, usually occurs at the very end of the molt, after the full development of other parts plumage.

The different types of molt in birds can be broadly described as follows. When leaving the egg, the young bird is dressed embryonic fluff, which is replaced by the first outfit of outline (definitive) feathers. This (first) outline feather outfit is called nesting... Often it is distinguished by a special color (often similar to that of females), softness and lower feather density, as well as greater width, and sometimes also the length of the tail and primary feathers. Birds wear their nesting outfit for different periods of time - from several weeks to 16-18 months. Many passerines change it - post-nesting molt takes place at the end of summer. In pigeons, rolling rollers and owls, it occurs in the first fall. Birds of prey begin to molt at the age of about one year - sparrowhaws around May, golden eagles in April, peregrine falcons in March and May; their molt ends in late autumn or early winter, so they still nest in the nesting plumage with a small admixture of feathers of the next plumage. Many waders, as well as shepherdesses, hens and toadstools, molt, changing their nesting outfit, in autumn or winter at the age of 5-8 months; herons molt later in spring; at the age of 8-10 months, tube-noses replace the nesting outfit. In ducks, post-nesting molt begins in September and ends in winter or even by spring.

Post-nesting molt sometimes leads to a change in the entire plumage and is then called complete, or with it only part of the plumage (small feathers) is replaced, and then it is called partial... An example of a partial post-nesting molt in passerines is the molting of families of ravens, finches, wagtails, titmice, flycatchers, warblers, and thrush. For example, in the white wagtail at the age of about 2% of the month, head coverts, bodies, small and medium wing coverts, part of large wing coverts, internal secondary flight feathers, and sometimes the middle pair of tail feathers are replaced. However, the amount of this partial molt is different in different genera. In other passerines (larks, starlings, etc.), the post-nesting molt is complete. After a complete post-nesting molt, the bird puts on an outfit that will be worn for a year and replaced, or once a year and completely - this is the so-called annual outfit(falcon, hawk, starlings, larks), or (which is rare) will change twice a year (the so-called premarital outfit common black grouse, city swallow).

With partial post-nesting molt, subsequent molts can cover the entire plumage. Then the outfit worn by the bird as a result of the post-nesting molt is called combined annual outfit(since in it large plumage, in particular flight and tail feathers, remains from the nesting plumage); such an outfit is worn, for example, by ravens, tits, common oatmeal, mountain bunting (but not all oatmeal). If the outfit, worn as a result of a partial post-nesting molt, will then be replaced twice a year, then it is called combined premarital outfit(flycatchers, wagtails, many warblers).

Further molts take place like this. The annual outfit changes as a result of molting, which usually occurs in late summer - early autumn. This molt is called annual molt... In the event that the color of the annual outfit worn as a result of the post-nesting molt differs from the final coloration of adult birds (this happens, for example, in great gulls, eagles and sea eagles), the corresponding annual outfit is marked as transition... If three or four years pass before receiving the final outfit, then we have the corresponding bird first transitional annual outfit, second transitional annual outfit etc.

The change of the wedding dress, like the change of the annual dress, takes place in late summer - early autumn. Subsequent molts take place regularly according to this scheme. Birds wearing the annual outfit change it once a year as a result of the annual molt. In forms that molt twice a year, the intermarital, or postnuptial, attire as a result of mating is replaced by a combined moult, then the postnuptial moult occurs, etc.

In many cases, molting brings with it a discoloration. Sometimes, by spring, a change in color in birds is obtained without molting, as a result of the stripping of the edges of the feathers and the emergence of bright flowers that were covered by the edges of the feathers (for example, in small finches, buntings, etc.). But, contrary to the opinion of the old authors, no repainting of the grown pen - a physiologically dead formation - does and cannot occur. The nuptial attire is usually brighter than the intermarriage attire, and sex differences are more pronounced in it. The molting process reaches the greatest complexity in the ptarmigan, in which four outfits can be distinguished per year: two of them (spring and winter) correspond to breeding and interbreeding, and summer and autumn ones have no analogies among other groups of birds.

Different animals react differently to adverse changes the environment, such as a decrease or increase in temperature, falling snow cover, a decrease in the amount of food. With such changes, many animals reduce their vital activity, become inactive, hide in various kinds of shelters, and finally fall into a state of numbness, the so-called hibernation. This happens in reptiles and even in many mammals.

The bird is another matter. Their body reacts to the above changes in the environment with increased activity. The most vivid expression of this specificity of the activity of the avian organism is found in seasonal flights, or migrations(fig. 15). Many hypotheses, often contradictory, have been expressed about the origin of flights. In general form, based on the data of the modern pattern of flights, our information about the climates of past geological times, etc., it can be assumed that the origin of this phenomenon cannot be associated only with the events of the so-called ice age, when the widespread on the continent of Europe and Asia glaciers made the northern hemisphere unsuitable for many species of birds (and other animals).

Flights arose as a result of periodic changes in climatic conditions associated with the changing seasons. They, apparently, existed in Tertiary times, before the onset of the great glaciation. This is indirectly indicated by the existence of regular migrations of many bird species in the tropical and subtropical zones. Quaternary glaciation, of course, influenced the migration pattern of birds in the northern hemisphere, but it was not the reason for their occurrence. At the same time, it should be remembered that the unevenness of glaciation, the displacement of the centers of glaciation in the meridional direction (which caused a difference in climate not only along the north-south line, but also along the west-east line) should have had a very difficult effect on changes in the nesting areas and wintering areas of birds and to create in many places an environment convenient for nesting, but not for a sedentary lifestyle. A long northern day has always, of course, been favorable for feeding offspring, and the intensity of illumination in the north for native bird species was a necessary condition for the normal development of the genitals during the breeding season. The general retreat of glaciers, which created a more favorable climatic situation and thereby stimulated reproduction, caused the birds in the northern hemisphere to occupy new nesting territories, which, however, had to be periodically released due to large differences between the seasons. It can be assumed that the territory and directions of migration in most cases reflect the path of introduction of the bird into this nesting area. The general scheme of the phenomenon of migration in the historical perspective is reduced to the adaptation of the bird organism to cover large distances in order to find the most favorable territories for its existence, with stimuli associated with reproduction prevailing in spring, and stimuli associated with nutrition in autumn. The direct causes of flights have to be considered a complex interaction of both external and internal factors. It is impossible to reduce all phenomena to only one of these reasons, as many do. The feeding conditions (associated with the deterioration of the conditions for obtaining food, a decrease in the number of prey, a reduction in the daylight hours, etc.) can undoubtedly explain to a certain extent the autumn departure. However, this phenomenon is associated with the onset of certain physiological changes in the body, accompanying the end of the reproduction period.

The influence of external conditions on the state of the body of birds has been repeatedly mentioned above. It is useful to recall here that birds living all year round in monotonous and rather favorable conditions lead a sedentary lifestyle. It can be assumed that the stimuli for flights are fluctuations in the body's nutrition, periodically caused by changes in external conditions, which are inextricably linked with certain phases of the annual activity of the gonads. Since the periodicity of nesting cycles for birds is hereditary, the very desire to migrate should be congenital in some forms. The question of "attachment" of birds to the nesting territory and competition are also of great importance.

The specific phenological situation does not determine the beginning of flights, although, of course, it affects their course. Wind, for example, matters, especially a strong wind in the opposite direction of flight. In general, however, the autumn departure of birds coincides with the end of the breeding season, but does not always immediately follow. The intermediate stage for many species is the formation of flocks and migrations. As a rule, areas with a cold climate are occupied in spring later and are left in autumn by birds earlier than warmer ones. In some species, females fly earlier than males; for others, the opposite is true; in most species, both sexes fly at the same time. Often in the fall, young birds fly off earlier than old ones. The order of flight of birds is also different; some species fly during the day, others at night, some silently, others emit characteristic cries (the cries of cranes, the cackle of geese, etc.). At night, those species that are forced to expend a lot of energy during the flight usually fly, this requires increased feeding during the day. During the day, well-flying forms fly, which can, to a large extent, get by with the accumulated energy reserves in the body during flights. It is known that before the flight, birds are usually very well-fed. The autumn formation of reserve energy sources (fats, glycogen, protein) is associated not only with increased nutrition, but also with the extinction of the activity of the gonads.

The study of bird migrations by the ringing method has finally proved that for each bird and for each bird population of a particular region, flights occur between the nesting place and the wintering place, and, as a rule, the bird returns in the spring to the same place where it hatched or nested in the previous year. This is closely related to the repeatedly noted conservatism of birds with regard to the choice of habitat. In the same way, wintering places are strictly defined. Of course, there are some deviations from this general scheme, but these are exceptions.

The ecological situation of a particular area, of course, determines its suitability as a wintering place, but the wintering site will not always be the closest ecologically favorable area to the nesting site. Probably, competition in the form of occupation of the nearest areas convenient for wintering by other populations of this species is also important here. For example, perhaps this is why northern forms of one species often hibernate farther south than subspecies of the same species nesting in the middle lane, and so on. To explain the emergence of distant wintering sites, it is necessary to involve historical reasons as well. This can be seen, for example, during the flights of the dispersing species. The green warbler, which has spread to the west in recent decades, still winters in Southeast Asia; lentils do the same; talovka warbler from Scandinavia flies to India for the winter; on the other hand, the horned lark, which had recently settled in northern Scandinavia, began to winter in England.

Favorable climatic conditions largely determine the suitability of a particular area for wintering. Therefore, for example, in Europe, many migratory birds fly not only in the south, but also in the west. England, with its mild winters and light snowfalls, provides, for example, shelter for many Central and Northern European birds - passerines, woodcocks, lapwings, etc. Southwestern Europe and especially the Mediterranean attract more more birds... There is a huge concentration of birds in the Nile Valley. African wintering grounds are generally very abundant, with 76 European bird species reaching the Cape. Some Siberian and Arctic birds also come here.

In Western Europe and North Africa many of our game birds winter - waterfowl and quail (which, unfortunately, suffer greatly from the disorder of hunting in Mediterranean countries).

In India, in the south of China, on the islands of the Indo-Australian archipelago, there are massive wintering grounds for many northern and arctic birds. On the territory of the USSR, masses of waterfowl winter in the South Caspian, where the Kyzyl-Agachsky named after V. SM Kirov and Hasan-Kuli nature reserves (the first in Lankaran, the second in the lower reaches of the Atrek in Turkmenistan). In the form of a diagram, it can be assumed that most of the northern birds nesting west of the Yenisei fly to the southwest in autumn (many of them winter in India); birds from Trans-Yenisei Siberia fly mainly to Southeast Asia skirting the inhospitable Central Asian deserts and mountains. Some birds travel an even farther journey, reaching, as do the East Siberian Godwits and Icelandic Sandpipers, New Zealand. In America, unlike in Europe, the influence of the Gulf Stream does not cause fly-over movement, and the birds fly more or less directly to the south. It should be added that the wintering sites of different subspecies of the same species are usually well delineated.

The direction of flights is determined, of course, by the location of nesting and wintering sites. At the same time, with a known number of exceptions, the movement proceeds in ways that are as favorable in the ecological sense as possible (convenience of orientation, nutrition, rest, etc.), which are very significant factors here; in particular, aquatic birds tend to adhere to rivers, lakes, etc. The general directions of migration (autumn) in Europe are west, southwest, less often south and southeast; in North America, as already mentioned, the predominant direction is south and southeast; in Asia - south, southwest, less often southeast and east.

The directions of departure and arrival do not always coincide, and the speeds of spring arrival and autumn departure often do not coincide (arrival usually goes "more friendly" and sooner). The movement of birds through ecologically favorable stations was the reason for the emergence of a widespread flyway theory until recently. According to the theory developed by Palmen, birds on flights seem to move only along relatively narrow and strictly fixed "paths", and do not fly outside of them. In fact, the movement of birds is different.

Landscape factors, as well as the conditions for feeding, resting, etc., determine the movement of flocks of migratory birds. Vast mountain ranges can therefore cause a roundabout direction of flight (for example, this explains the insignificance of the passage through high Central Asia). Water bodies favor aquatic birds, but terrestrial birds, if possible, avoid the ocean and fly over it (with rare exceptions) near the coast and over the shortest distances. Continental water basins do not serve as an obstacle for land birds flying through the North, and through the Baltic, and through the Mediterranean, and through the Black Sea. Birds of the sea coasts, for example, many waders, and during flights stick to the coasts. For example, some waders from Northeast Siberia move south along the Pacific coast, while sandpipers from Northern Europe move along the coasts of Scandinavia, the Baltic, and the Atlantic Ocean. Flocks of waterfowl migratory birds attract migratory predators.

It should be noted that some birds on the flights are more gregarious (for example, storks, cranes), in others the connection between individual individuals and groups of individuals is weaker.

It is necessary to distinguish from flights the migrations undertaken by many species in connection with the onset of unfavorable conditions, and irregular and accidental evictions from the nesting area, examples of which we see in saji. Mountain forms undertake more or less regular vertical migrations.

The complex functioning of the motor apparatus of birds, especially during flight, requires a complex orientation mechanism. Let us dwell a little on this issue. The sense of smell in birds, in contrast to mammals, is poorly developed. Hearing in birds functions excellently, but the first place among the senses belongs to vision. In this respect, birds rank first among other animals. It is characteristic that among birds there are no forms with underdeveloped eyes at all, let alone blind ones. The very size of the eyes is very large, and the volume of an eye, for example, a hawk, is approximately equal to the volume of a human eye.

The field of vision in birds is large, but vision is predominantly monocular and lateral (lateral) (Fig. 16). The general field of view in birds with a pronounced lateral (lateral) position of the eyes (for example, in passerines) is 300 ° (in humans, only about 200 °), the lateral field of view of each eye is 150 ° (i.e., 50 ° more, than humans). But the field of binocular vision, that is, the area of ​​coincidence of the fields of view of both eyes in front of the bird, is only 30 ° (in humans - 150 °). In birds with a wider head and with eyes more or less forward (lateral-frontally), the general field of view is the same, but the field of binocular vision is wider - about 50 ° (this includes nightjars, birds of prey and some others). In owls, finally, with their eyes facing forward (frontal position), the lateral field of view of each eye is only 80 ° (less than that of humans); this is partly due to the fact that their eyes are completely motionless; the immobility of the eyes in owls is compensated by the mobility of the neck, in particular the great freedom of its rotation (up to 270). The maximum value of the field of binocular vision in birds. is 60 °. As a rule, the movement of each eye and its visual perception in birds are independent; the visual fields of both eyes are also independent; due to the movements of the bird's head, they can diverge, converge and overlap.

The visual acuity in birds is very high, and the minimum of perception is much higher than that in humans (in the hawk, for example, 4 times): the peregrine falcon sees turtle doves at a distance of more than 1000 m... There is reason to believe that birds rank first among all animals in terms of perception of space and distance. This, of course, is directly related to the speed of movement of birds in the air.

Perhaps, with the hearing aid in birds, there is a sense of position in space, or of a geographical position, which is undoubtedly available, but the mechanism of which remains unclear until recently. This feeling is the most interesting aspect of orientation in birds. In a number of cases, the bird's finding of the goal of movement cannot be explained by either optical stimuli or visual memory. So, for example, among swifts, swifts, which nest colonially in deep dark caves (the city of Padanga in Sumatra has a cave with a depth of 2 km where the swiftlet colony is located), each bird unmistakably finds its nest among others in complete darkness. South American guajaro nightjars also nest colonially in deep, dark caves. In this case, orientation is carried out using echolocation.

The impossibility of explaining the finding by migratory birds of the target (nesting or wintering place) by visual stimuli or motor memory alone is indicated by at least the fact that many species fly at night, that in many migratory birds young birds born in summer fly off earlier than old ones in autumn (and, therefore , independently of them and without any experience and example, make their first journey to winter). Many species nesting in the Canary Islands, such as some swifts, overwinter on the African mainland and therefore fly over the open ocean 50 km to the first islands lying on their way (Palma and Tenerife). Finally, numerous experiments were carried out on the importation of birds from the nests, and the birds returned unmistakably from distances of tens, hundreds and even more than a thousand kilometers. Kluyver (1936) in Holland drove starlings from their nests at a distance of 150 km, moreover, the birds were under anesthesia, and 60% of them still returned. This ability to determine geographic location is especially developed in migratory birds. The sense of geographic location not only guides the birds in a certain direction at a certain time, but also stimulates the birds to fly in a certain direction. In the development of this feeling, as we see in the example of carrier pigeons, it has known meaning both heredity and exercise, and the appearance and consolidation of it in birds is associated with natural selection (those individuals survived that unmistakably found the purpose of movement).

Of the existing explanations, the most probable is the connection between the sense of geographic location and certain magnetic phenomena, since it is difficult to imagine any other universal stimulus that changes in connection with changes in geographic location.

In the field of bird classification, there is still no generally accepted system. Different researchers distinguish between more and less units. In this book, based on the features of the structure, lifestyle, as well as probable origin and family ties, we single out the following groups of birds, to which we attach importance to orders. This division of orders is very close to the order system proposed at one time by the famous ornithologist E. Stresemann, and to the order system adopted in the book "Birds" by G. P. Dement'ev (Manual of Zoology, volume six, 1940). Many ornithologists distinguish larger groups of birds into orders; in such systems, the orders named below acquire the significance of suborders.

Class of birds in it modern form It does not split into subclasses (the extinct Archeopteryx is allocated into a special subclass), but 2 super-orders can be distinguished in it: penguins(Impennes) and typical, or new palates, birds(Neognathae). It is possible that ratites should be allocated to a special superorder; the latter should be named running birds(Ratidae). We adhere to the ordering order recommended as the standard for faunistic publications by the XI International Ornithological Congress in Basel in 1954 (Wetmer's system).

Classification of modern birds

Superorder Penguins (Impennes)

1. Squad Penguins (Sphenisciformes)

Superorder New palatine, or Typical, birds (Neognathae)

2. Order Ostriches (Struthioniformes)

3. Detachment Nandu (Rheiformes)

4. Squad of Emu and Cassowary (Casuariiformes)

5. Squad Kiwi (Apterygiformes)

6. Squad Tinamu (Tinamiformes)

7. Detachment Loon (Gaviae, or Gaviiformes)

8. Order of the Toadstool (Podicipedes, or Podicipediformes)

9. Squad Pipe-nosed (Procellariiformes)

10. Squad Copepods (Steganopodes, or Pelecaniformes)

11. Squad Ankle (Gressores)

12. Squad Flamingo (Phoehicopteri)

13. Order Anseriformes (Anseres, or Anseriformes)

14. Order Day birds of prey (Accipitres, or Falconiformes)

15. Squad Chicken (Galliformes)

16. Order Shepherd partridges (Mesoenades)

17. Detachment Three-finger (Turniceps)

18. Detachment Cranes (Grues, or Gruiformes)

19. Order Shepherd (Ralli, or Ralliformes)

20. Squad Pawpaw (Heliornithes)

21. Kagu Squad (Rhinocheti)

22. Squad Sun Herons (Eurypygae)

23. Unit Series (Cariamae)

24. Squad Bustard (Otides) *

* (Detachments from shepherd partridges to Bustards, inclusive, sometimes unite into one detachment called crane-like. )

25. Squad Kuliki (Limicolae)

26. Squad of the Seagull (Lari, or Lariformes)

27. Squad of Guillemots (Alcae, or Alciformes) *

* (Detachments of sandpipers, gulls and guillemots sometimes unite into one detachment called charadriiformes. )

28. Order of Grouse (Pterocletes, or Pterocletiformes)

29. Squad Pigeons (Columbae, or Columbiformes)

30. Squad Parrots (Psittaci)

31. Order of the Cuckoo (Cuculiformes)

32. Squad of Owls (Striges, or Strigiformes)

33. Caprimulgi Squad

34. Squad Long-winged (Macrochires)

35. Order of bird-mouse (Colii)

36. Trogon squad (Trogones)

37. Squad Raksha (Coraciae)

38. Squad Hoopoe (Upupae)

39. Squad Woodpecker (Picariae)

40. Order Passeriformes