Which bird has the most developed sense of smell? Birds' sense of smell is poorly developed. Territory for mating only

The quietest bird on Earth is the common pika (Certhia familiaris), which is also found in Ukraine. She makes sounds so high that they can barely be heard.

The loudest calls of all birds are made by the Indian peacock - they can be heard several kilometers away.

The largest joint nesting sites are organized by gannets and great cormorants. More than 10 million of these birds nest annually on the islands of the fish-rich rivers of Peru.

The rarest bird lives on the Hawaiian Islands and bears the unusual name “Kauai e-uh”. In 1980, there was only one couple left in the entire world! It is possible that the "Kauai uh" will soon be officially declared an endangered species.

Swans have the largest number of feathers - over 25 thousand pieces!

The most ferocious and successful predators in the bird world are hawks (Accipiter) and kites (Milvus). They are distinguished by their high flight speed and, falling like a stone from a height onto their prey, inflict terrible wounds on it with their powerful claws.

What are the most common poultry? Of the total number of birds on earth, which is approximately 100 billion, about 3 billion are domestic chickens.

Among wild birds, the champion in numbers is the representative of the passerine order - the red-billed weaver (Qvelea qvelea). Over 10 billion of these birds live in West Africa! Even the annual destruction of over 200 million weaver birds does not affect their numbers.

The deepest diver is the emperor penguin. He is able to dive to a depth of 1.5 km and quickly return to the surface, which saves him from decompression.

The largest waterfowl is the same emperor penguin. Its height reaches 1.2 m, its pectoral fin span is 1.3 m, and its weight is 42.6 kg, which is more than twice the weight of any flying bird. True, the emu, with a height of about 2 m, although it is a land bird, is capable of swimming well.

The male emperor penguin (Aptenodytes forster) can withstand the longest fast of all birds. It can survive without food for up to 134 days.

Among long-lived birds, the absolute record holder is the condor, which lives in the Andes. One of these birds lived in captivity for 72 years.

The Andean condor is also the largest flying bird. Its wingspan reaches 3.25 m, and its weight is up to 12.4 kg.

The largest flightless bird is the African ostrich (Struthio camelus). The height of some specimens reaches 2.7 m, and the weight is 150-175 kg. Interestingly, females are larger than males, which are rarely heavier than 155 kg. Even larger flightless birds (over 3 m tall) were those that lived in Madagascar and were exterminated in the 17th-18th centuries. ostrich-like apyornis.

The largest egg is an ostrich egg. Its length is 13.5 cm and its weight is 1.65 kg. The weight of such an egg is equal to 18 chicken eggs, and it will take about 40 minutes to soft-boil it. The eggs of the apiornis exterminated in Madagascar weighed 7.5-8 kg!

The strongest egg is also an ostrich egg. It can support a person weighing up to 115 kg.

The largest forest bird is the helmeted cassowary (Casuarius casuaries), which lives in Australia and New Guinea, whose height is 1.5 m.

The smallest birds on our planet are male pygmy bumblebee hummingbirds (Mellisuga helenae) living in Cuba. They have a mass of 1.6 g, and their length is 5.5-5.7 cm. Half of the length is the beak and tail.

The smallest nests of all birds are also found in bumblebee hummingbirds. They are the size of a thimble.

The smallest egg can be laid by a hummingbird-bee. It weighs 0.2 g. In the verbena hummingbird, the eggs are less than 1 cm long and weigh 0.37 g.

The largest “incubator” nests are built by many generations of weed chickens (Leipoa ocellata) living in Australia. They reach 4.75 m in height, 10.6 m in width, and their weight amounts to tens of tons.

The heaviest modern flying bird is the bustard (Otis, or Otides), whose weight reaches 19-20 kg.

The fastest flight is made by the peregrine falcon (Falco peregrinus). It is capable of speeds of 200-270 km/h.

The sooty tern (Sterna fuscata) is considered to be the “most flying bird.” Leaving its nesting sites, it stays in the air for 3 to 10 years, only descending onto the water from time to time.

The record holder for the longest flight distance is the gray petrel (Puffinus griseus). During migration, the length of its flight averages about 64,000 km.

The peregrine falcon (Falco peregrinus) has the sharpest vision of all birds. Under ideal conditions, he can see a pigeon over 8 km away.

Whooper swans (Cygnus cygnus) can fly the highest. In 1967, they were spotted by an airplane pilot at an altitude of just over 8,230 m above the Hebrides (UK). The height was confirmed by the tracking station workers.

The largest wingspan (about 7.6 m) was that of the teretoron (Argentavis magnificens), which lived in South America 6-8 million years ago.

The longest step (sometimes over 7 m) is capable of the ostrich.

The fastest land bird is also the ostrich. He can run at a speed of 72 km/h.

The only bird on our planet without wings and a tail is the kiwi (Apteryx australis). This creature, whose body is covered with hair-like feathers, lives in the forests of New Zealand. Kiwi is also one of the few birds that have a well-developed sense of smell. The kiwi's nostrils are not located at the base of the beak, but at the end. At the base of the beak there are “whiskers” or tactile whiskers. By sticking its long and flexible “nose” into the damp soil, the kiwi sniffs out worms and insects. By the way, the total weight of the eggs laid by the females of these birds (usually from 4 to 6) is almost equal to the weight of their body.

The only bird born with claws on its wings is the hoazin (Opisthocomus hoazin), found in Brazil, Venezuela and eastern Colombia.

The hoatzin is also considered the stinkiest bird. Its meat has a pungent, musty and nauseating odor. European settlers in South America even called it "forest stinker", and Colombians called it Pava hedionda ("stinking pheasant"). The smell is believed to be related to the hoatzin's diet (green foliage) and its special digestive system (fermentation of food occurs in the foregut).

Hummingbirds (Trochilidae) have the highest metabolic rate. Birds from this family require an amount of food equal to at least half their body weight.

The fastest wing movements are performed by the horned hummingbird (Heliactin cornuta) from South America - up to 90 beats per second.

The rarest wing movements during flight are performed by vultures from the family Cathartidae - one beat per second.
Date: 01/24/2013 06:48:35 Visitors: 8539

Common pika (Certhia familiaris)

Indian peacock

Northern gannet

Great cormorant

Swan

Hawk

Kite

Domestic chickens

Red-billed weaver (Qvelea qvelea)

Emperor penguin

Pitoui

Condor

African ostrich (Struthio camelus)

Epiornis egg, ostrich egg and hummingbird egg

Ostrich

Helmeted cassowary (Casuarius casuaries)

Hummingbird

The content of the article

BIRDS(Aves), a class of vertebrates that includes animals that differ from all other animals by the presence of feathers. Birds are distributed throughout the world, are very diverse, numerous and easily accessible to observation. These highly organized creatures are sensitive, receptive, colorful, elegant and have interesting habits. Because birds are highly visible, they can serve as a useful indicator of environmental conditions. If they prosper, then the environment is prosperous. If their numbers are declining and they cannot reproduce normally, the state of the environment most likely leaves much to be desired.

Like other vertebrates - fish, amphibians, reptiles and mammals - the basis of the bird skeleton is a chain of small bones - vertebrae on the dorsal side of the body. Like mammals, birds are warm-blooded, i.e. their body temperature remains relatively constant despite fluctuations in ambient temperature. They differ from most mammals in that they lay eggs. Characteristics specific to the class of birds are primarily associated with the ability of these animals to fly, although some of their species, such as ostriches and penguins, lost it during their later evolution. As a result, all birds are relatively similar in shape and cannot be confused with other taxa. What makes them stand out even more is their feathers, which are not found on any other animal. So, birds are feathered, warm-blooded, oviparous vertebrates, originally adapted for flight.

ORIGIN AND EVOLUTION

Modern birds, according to most scientists, descend from small primitive reptiles, pseudosuchians, who lived in the Triassic period approximately 200 million years ago. Competing with their fellow creatures for food and escaping from predators, some of these creatures, over the course of evolution, became increasingly adapted to climbing trees and jumping from branch to branch. Gradually, as the scales lengthened and turned into feathers, they acquired the ability to plan, and then to be active, i.e. waving, flying.

However, the accumulation of fossil evidence has led to the emergence of an alternative theory. More and more paleontologists believe that modern birds descended from small carnivorous dinosaurs that lived at the end of the Triassic and Jurassic periods, most likely from the so-called group. coelurosaurs. These were bipedal forms with long tails and small forelimbs of the grasping type. Thus, the ancestors of birds did not necessarily climb trees, and there was no need for a gliding stage to develop active flight. It could have arisen on the basis of the flapping movements of the forelimbs, probably used to knock down flying insects, for which, by the way, predators had to jump high. At the same time, transformations of scales into feathers, reduction of the tail and other profound anatomical changes took place.

In light of this theory, birds represent a specialized evolutionary lineage of dinosaurs that survived their mass extinction at the end of the Mesozoic era.

Archeopteryx.

The connection between birds and reptiles was made possible by the discovery in Europe of the remains of an extinct creature - Archeopteryx ( Archaeopteryx litographica), who lived in the second half of the Jurassic period, i.e. 140 million years ago. It was approximately the size of a pigeon, had sharp, slotted teeth, a long lizard-like tail, and forelimbs with three toes bearing hooked claws. In most features, Archeopteryx was more like a reptile than a bird, except for the real feathers on the forelimbs and tail. Its features show that it was capable of flapping flight, but only over very short distances.

Other ancient birds.

Archeopteryx for a long time remained the only link between birds and reptiles known to science, but in 1986 the remains of another fossil creature were found that lived 75 million years earlier and combined the characteristics of dinosaurs and birds. Although this animal was named Protoavis(protobird), its evolutionary significance is controversial among scientists. After Archeopteryx, there is a gap in the fossil record of birds lasting ca. 20 million years. The following findings date back to the Cretaceous period, when adaptive radiation had already led to the emergence of many bird species adapted to different habitats. Among the approximately two dozen Cretaceous taxa known from fossils, two are particularly interesting: Ichthyornis And Hesperornis. Both were discovered in North America, in rocks formed on the site of a vast inland sea.

Ichthyornis was the same size as Archeopteryx, but in appearance it resembled a seagull with well-developed wings, indicating the ability of powerful flight. Like modern birds, it had no teeth, but its vertebrae were similar to those of a fish, hence its generic name, meaning “fish bird.” Hesperornis ("western bird") was 1.5–1.8 m long and almost wingless. With the help of huge flipper-like legs extending sideways at right angles at the very end of the body, it apparently swam and dived no worse than loons. It had teeth of a "reptilian" type, but the structure of the vertebrae was consistent with that typical of modern birds.

The appearance of flapping flight.

In the Jurassic period, birds acquired the ability to actively fly. This means that thanks to the swings of their forelimbs, they were able to overcome the effects of gravity and gained many advantages over their terrestrial, climbing and gliding competitors. Flight allowed them to catch insects in the air, effectively avoid predators and choose the most favorable environmental conditions for life. Its development was accompanied by a shortening of the long, cumbersome tail, replacing it with a fan of long feathers, well adapted for steering and braking. Most of the anatomical transformations necessary for active flight were completed by the end of the Early Cretaceous (about 100 million years ago), i.e. long before the extinction of the dinosaurs.

The emergence of modern birds.

With the onset of the Tertiary period (65 million years ago), the number of bird species began to increase rapidly. The oldest fossils of penguins, loons, cormorants, ducks, hawks, cranes, owls and some song taxa date back to this period. In addition to these ancestors of modern species, several huge flightless birds appeared, apparently occupying the ecological niche of large dinosaurs. One of them was Diatryma, discovered in Wyoming, 1.8–2.1 m tall, with massive legs, a powerful beak and very small, underdeveloped wings.

At the end of the Tertiary period (1 million years ago) and throughout the early Pleistocene, or glacial era, the number and diversity of birds reached a maximum. Even then, many modern species existed, living side by side with those that later became extinct. A wonderful example of the latter - Teratornis incredibilis from Nevada (USA), a huge condor-like bird with a wingspan of 4.8–5.1 m; it is probably the largest known bird capable of flight.

Recently extinct and threatened species.

Humans in historical times undoubtedly contributed to the extinction of a number of birds. The first documented case of this kind was the destruction of the flightless pigeon-like dodo ( Raphus cucullatus) from the island of Mauritius in the Indian Ocean. For 174 years after the discovery of the island by Europeans in 1507, the entire population of these birds was exterminated by sailors and the animals they brought on their ships.

The first North American species to become extinct at the hands of humans was the great auk ( Alca impennis) in 1844. It also did not fly and nested in colonies on the Atlantic islands near the continent. Sailors and fishermen easily killed these birds for meat, fat and to make bait for cod.

Soon after the disappearance of the great auk, two species in the east of the North American continent became victims of humans. One of them was the Carolina parrot ( Conuropsis carolinensis). Farmers killed these flocking birds in large numbers as thousands of them regularly raided gardens. Another extinct species is the passenger pigeon ( Ectopistes migratorius), mercilessly exterminated for meat.

Since 1600 it has probably disappeared worldwide. 100 species of birds. Most of them were represented by small populations on sea islands. Often incapable of flight, like the dodo, and almost unafraid of man and the small predators brought by him, they became easy prey for them.

Currently, many bird species are also on the verge of extinction or, at best, under threat. In North America, the California condor, yellow-legged plover, whooping crane, Eskimo curlew and (possibly now extinct) ivory-billed woodpecker are among the most distressed species. In other regions, the Bermuda typhoon, the Philippine harpy, the kakapo (owl parrot) from New Zealand, a flightless nocturnal species, and the Australian ground parrot are in great danger.

The birds listed above found themselves in an unenviable position mainly due to the fault of humans, who brought their populations to the brink of extinction through uncontrolled hunting, ill-considered use of pesticides or radical transformation of natural habitats.

SPREADING

The distribution of any bird species is limited to a specific geographical area, the so-called. habitat, the size of which varies greatly. Some species, such as the barn owl ( Tyto alba), almost cosmopolitan, i.e. found on several continents. Others, say the Puerto Rican scoop ( Otus nudipes), the range does not extend beyond one island. Migratory species have nesting areas in which they breed, and sometimes wintering areas that are very remote from them.

Thanks to their ability to fly, birds are prone to widespread distribution and, whenever possible, expand their ranges. As a result, they are constantly changing, which, of course, does not apply to the inhabitants of small isolated islands. Natural factors can contribute to the expansion of the range. It is likely that prevailing winds or typhoons around 1930 transported the Egyptian heron ( Bubulcus ibis) from Africa to the eastern shores of South America. From there it began to quickly move north, in 1941 or 1942 it reached Florida, and is now found even in southeastern Canada, i.e. its range covered almost the entire east of North America.

Humans have contributed to the expansion of their ranges by introducing species into new regions. Two classic examples are the house sparrow and the common starling, which migrated from Europe to North America in the last century and spread throughout that continent. By changing natural habitats, humans have also inadvertently stimulated the spread of certain species.

Continental areas.

Land birds are distributed across six zoogeographic regions. These areas are as follows: 1) Palaearctic, i.e. non-tropical Eurasia and northern Africa, including the Sahara; 2) Nearctic, i.e. Greenland and North America, except for the lowland part of Mexico; 3) Neotropics - plains of Mexico, Central, South America and the West Indies; 4) Ethiopian region, i.e. Sub-Saharan Africa, southwestern corner of the Arabian Peninsula and Madagascar; 5) Indo-Malayan region, covering the tropical part of Asia and the adjacent islands - Sri Lanka (Ceylon), Sumatra, Java, Borneo, Sulawesi (Celebes), Taiwan and the Philippines; 6) Australian region - Australia, New Guinea, New Zealand and the islands of the southwest Pacific, including Hawaii.

The Palaearctic and Nearctic regions are inhabited by 750 and 650 bird species, respectively; this is less than in any of the other 4 areas. However, the number of individuals of many species there is much higher, since they have larger habitats and fewer competitors.

The opposite extreme is the Neotropics, where approx. 2900 species of birds, i.e. more than in any other area. However, many of them are represented by relatively small populations confined to individual mountain ranges or river valleys of South America, which is called the “Bird Continent” due to the abundance and diversity of birds. Colombia alone has 1,600 species, more than any other country in the world.

The Ethiopian region is home to approximately 1,900 bird species. Notable among them is the African ostrich, the largest modern representative of this class. Of the 13 families endemic to the Ethiopian region (i.e., not extending beyond its borders), five are found exclusively in Madagascar.

In the Indo-Malayan region there are also approx. 1900 species. Almost all pheasants live here, including the Indian peacock ( Pavo cristatus) and bank junglefowl ( Gallus gallus), from which the domestic chicken originated.

The Australian region is inhabited by approximately 1200 species of birds. Of the 83 families represented here, 14 are endemic, more than in any other area. This is an indicator of the uniqueness of many local birds. Endemic groups include large flightless kiwi (in New Zealand), emus and cassowaries, lyrebirds, birds of paradise (mainly in New Guinea), bower birds, etc.

Island habitats.

As a rule, the farther oceanic islands are from continents, the fewer bird species there are. The birds that managed to reach these places and survive there are not necessarily the best fliers, but their ability to adapt to their environment clearly turned out to be excellent. Long isolation on islands lost in the ocean led to the accumulation of evolutionary changes sufficient to transform the settlers into independent species. Example - Hawaii: despite the small area of ​​the archipelago, its avifauna includes 38 endemic species.

Marine habitats.

Birds that forage in the sea and visit land primarily for nesting are naturally called sea birds. Representatives of the order Procellariiformes, such as albatrosses, petrels, fulmars and storm petrels, can fly over the ocean for months and feed on aquatic animals and plants without even approaching land. Penguins, gannets, frigatebirds, auks, guillemots, puffins, most cormorants, and some gulls and terns feed primarily on fish in the coastal zone and are rarely found away from it.

Seasonal habitats.

In each specific territory, especially in the Northern Hemisphere, a given bird species can be found only in a certain season, and then migrate to another place. On this basis, four categories of birds are distinguished: summer residents, nesting in a given area in the summer, transit species, stopping there during migration, winter lodgers, arriving there for the winter, and permanent residents (sedentary species), which never leave the area.

Ecological niches.

No bird species occupies all parts of its range, but is found only in certain places, or habitats, for example in a forest, swamp or field. In addition, species in nature do not exist in isolation - each depends on the life activity of other organisms occupying the same habitats. Thus, each species is a member of a biological community, a natural system of interdependent plants and animals.

Within each community there are so-called. food chains that include birds: they consume some kind of food and, in turn, serve as food for someone. Only a few species are found in all parts of the habitat. Typically, some organisms inhabit the soil surface, others - low shrubs, others - the upper tier of tree crowns, etc.

In other words, each species of bird, like representatives of other groups of living things, has its own ecological niche, i.e. a special position in the community, like a “profession”. An ecological niche is not identical to the habitat, or “address,” of a taxon. It depends on its anatomical, physiological and behavioral adaptations, i.e., say, on the ability to nest in the upper or lower tier of the forest, endure summer or winter there, feed during the day or at night, etc.

Territories with a certain type of vegetation are characterized by a specific set of nesting birds. For example, species such as ptarmigan and snow bunting are confined to the northern tundra. The coniferous forest is characterized by wood grouse and crossbills. Most of the species we are familiar with live in areas where natural communities have been directly or indirectly destroyed by civilization and replaced by anthropogenic (man-made) forms of the environment, such as fields, pastures and leafy suburbs. Such habitats are more widespread than natural habitats and are inhabited by numerous and diverse birds.

BEHAVIOR

A bird's behavior covers all its actions, from ingestion of food to reactions to environmental factors, including other animals, including individuals of its own species. Most behavioral acts in birds are innate, or instinctive, i.e. their implementation does not require previous experience (learning). For example, some species always scratch their head by raising their leg above the lowered wing, while others simply stretch it forward. Such instinctive actions are as characteristic of the species as body shape and coloring.

Many forms of behavior in birds are acquired, i.e. based on learning - life experience. Sometimes what seems to be pure instinct requires some practice for its normal expression and adaptation to circumstances. Thus, behavior is often a combination of instinctive components and learning.

Key incentives (releasers).

Behavioral acts are usually induced by environmental factors, which are called key stimuli, or releasers. They can be shape, pattern, movement, sound, etc. Almost all birds respond to social releasers - visual or auditory, with which individuals of the same species transmit information to each other or cause immediate responses. Such releasers are called signal stimuli, or demonstrations. An example is the red spot on the mandible of adult herring gulls, which triggers a feeding response in their chick.

Conflict situations.

A special kind of behavior arises in a conflict situation. Sometimes it is a so-called displaced activity. For example, a herring gull, driven from its nest by an intruder, does not rush into a counterattack, but instead preens its feathers, which are already in excellent condition. In other cases, she may show redirected activity, say in a territorial dispute, venting her hostility by pulling out blades of grass rather than engaging in a fight.

Another type of behavior in a conflict situation is the so-called. initial movements, or movements of intention. The bird crouches or raises its wings, as if trying to fly, or opens its beak and clicks it, as if wanting to pinch its opponent, but remains in place.

Marriage demonstrations.

All of these forms of behavior are of particular interest, since in the course of evolution they can be ritualized within the framework of the so-called. mating displays. Often the movements associated with them become emphasized and, therefore, more noticeable, which is facilitated by the bright coloring of the corresponding parts of the plumage. For example, offset feather preening is common in duck mating displays. Many species of birds use the raising of wings during courtship, which initially played the role of the initial movement in a conflict situation.

Addiction.

This word refers to the attenuation of a response to a repeated stimulus, which is not followed by either “reward” or “punishment.” For example, if you knock on a nest, the chicks raise their heads and open their mouths, since for them this sound means the appearance of a parent with food; If food does not appear several times after the shock, this reaction in the chicks quickly fades. Taming is also the result of habituation: the bird stops responding to human actions that initially frightened it.

Trial and error.

Learning by trial and error is selective (uses the principle of selection) and based on reinforcement. A fledgling that has left the nest for the first time in search of food pecks at pebbles, leaves and other small objects that stand out against the surrounding background. Eventually, through trial and error, he learns to distinguish stimuli that mean reward (food) from those that do not provide such reinforcement.

Imprinting (imprinting).

During a short early period of life, birds are capable of a special form of learning called imprinting. For example, a newly hatched gosling that sees a person before its own mother will follow on his heels, not paying attention to the goose.

Insight.

The ability to solve simple problems without trial and error is called “relationship capture,” or insight. For example, the woodpecker finch ( Catospiza pallida) from the Galapagos Islands “by eye” selects a needle from a cactus in order to remove the insect from a cavity in the wood. Some birds, in particular the great tit ( Parus major), they immediately begin to pull the food suspended on it towards themselves by the thread.

Individual behavior.

Social behavior.

Many bird actions relate to social behavior, i.e. relationships between two or more individuals. Even when solitary, they communicate with their sexual partners during the breeding season or with other individuals of their species occupying neighboring territories.

Communication.

Birds use complex communication systems that primarily involve visual and auditory signals or displays. Some of them are used to intimidate another individual during a conflict with it. A bird that has adopted a threatening pose often turns towards the enemy, stretches its neck, opens its beak and presses its plumage. Other demonstrations are used to appease the opponent. At the same time, the bird often draws in its head and fluffs its feathers, as if emphasizing its passivity and safety for others. The displays are clearly visible in the reproductive behavior of birds.

Defensive behavior.

All birds react with special defensive behavior to sound and visual stimuli associated with danger. The sight of a hawk in flight encourages small birds to rush to the nearest shelter. Once there, they usually “freeze,” holding their feathers down, legs tucked under, and keeping one eye on the predator. Birds with cryptic (camouflage, or protective) coloration simply squat in place, instinctively trying to blend into the background.

Crying and shouting warnings.

Almost all birds have a behavioral repertoire that includes alarm and warning calls. Although these signals were apparently not originally intended to scare other individuals of their species, they nevertheless induce flock members, mates, or chicks to freeze, crouch, or take flight. When confronted with a predator or other dangerous animal, birds sometimes use threatening actions, very similar to intraspecific threat displays, but more vivid in their manifestation. A group of small birds reacts to a predator sitting in the field of view, such as a hawk or an owl. shouting, similar to barking in dogs. It allows you to warn all birds in the immediate area about potential danger, and during the breeding season, to divert the enemy’s attention from hidden chicks.

Pack behavior.

Even outside the breeding season, most bird species tend to form flocks, usually of the same species. Apart from crowding in places where they spend the night, members of the flock maintain a certain distance from each other. For example, mountain swallows perch on wires with intervals of approximately 10 cm between individuals. An individual attempting to close this distance immediately faces a threatening display from its neighbor. Numerous sound signals emitted by all members of the flock help keep it from scattering.

Inside the flock there is a so-called social relief: if one individual begins to groom, eat, bathe, etc., those nearby soon begin to do the same. In addition, there is often a social hierarchy in a pack: each individual has its own rank, or “social position,” determined by gender, size, strength, coloring, health, and other factors.

REPRODUCTION

Reproduction in birds involves establishing a nesting territory, courtship, copulation, pairing, building a nest, laying eggs, incubating clutches and caring for growing chicks.

Territory.

At the beginning of the breeding season, individuals of most species establish the boundaries of their territory, which they protect from their relatives. Usually only the male does this. There are four types of such territories.

Territory for mating, nesting and feeding.

This type is the most common and characteristic, for example, of singing zonotrichia. The male arrives at the selected site in the spring and establishes its boundaries. Then the female arrives, mating occurs, a nest is built, etc. The pair searches for food for themselves and their chicks without leaving the territory.

Territory for mating and nesting, but not for feeding.

Many songbirds, including the red-winged trumpet, guard a fairly large territory around the nest, but go elsewhere in search of food.

Territory for mating only.

Males of some species use limited territories for mating displays and to attract females. They nest elsewhere without the participation of a sexual partner. Thus, several male sage-grouse attract females (“lekking”) by gathering in a small area called a lekking area.

Limited territory for mating and nesting.

Birds such as gannets, gulls, terns, herons and some species of swallows nest in colonies, in which each individual occupies the territory immediately surrounding the nest. They begin to build it in the same place where mating took place.

The territory that includes the feeding area must be large enough to provide food for both the breeding pair and its chicks. In a large bird, such as a bald eagle, it occupies an area of ​​about 2.6 km 2, and in song zonotrichia it is no more than 0.4 hectares. In species that nest in dense colonies, the size of the territory must be sufficient to prevent neighboring pairs from reaching each other with their beaks.

Singing.

The main sound demonstration of birds is song, i.e. a stable sequence of sounds that allows species to be identified. They are produced mainly by the male, and usually only during the breeding season. Any sounds can be used - from repetition of the same tone to a complex and long melody, sometimes very musical.

Birds sing especially often when establishing a nesting territory, less often after the chicks hatch, and usually stop singing when the young become independent and territorial behavior fades away. During the peak breeding season, one Zonotrichia sang 2,305 times a day. Some resident birds sing all year round.

Many birds try to catch the eye while singing, going to open places (perches). Larks, plantains and other inhabitants of treeless landscapes sing songs in flight.

Singing is most developed among the so-called. songbirds from the order Passeriformes, but almost all birds use one or another sound demonstration to announce their presence. They can come down to a kind of clucking in a pheasant or a roar in a penguin. Some birds make sounds not with the larynx, but with other parts of the body, making specific movements for this. For example, a woodcock, flowing over a forest clearing, soaring in a spiral into the sky, “grunts” due to sharp flapping of its wings, and then “cats” with its voice during a steep zigzag descent. Some woodpeckers, instead of song, use a drumbeat, beaten with their beak on a hollow stump or other object with good resonance.

During peak breeding season, some birds sing almost continuously all day. However, for most species, singing at dawn and in the evening is more common. The mockingbird and nightingale can sing on moonlit nights.

Pairing.

After the female arrives at the nesting site, the male activates his audio and visual displays. He sings louder and periodically chases the female. At first it is non-receptive, i.e. is not capable of fertilization, but after a few days its physiological state changes and copulation occurs. In this case, a more or less strong connection is often established between partners - a couple arises.

Songbirds are mostly monogamous. During the entire breeding season, they have only one partner, forming a stable pair with him. In some species, each nesting during one season is accompanied by a change of partner. Geese, swans and large birds of prey mate for life.

A number of species, including some songbirds, are characterized by polygamy. If a male mates with two or more females, it is said to be polygyny; if a female is with two or more males - about polyandry. Polygyny is more common (for example, in the rice troupial); Polyandry is known, say, in the American spotted carrier. Promiscuous copulation without the formation of stable pairs between partners is called promiscuity. It is characteristic, for example, of black grouse.

Following the formation of a pair, males take care of its preservation. They bring material for the nest, sometimes help build it, and usually feed the brooding female.

Types of nests.

Being warm-blooded, birds not only protect eggs from the influence of adverse weather conditions, but also warm them, promoting the development of the embryo. To do this, they must have a nest, i.e. any place where eggs can be laid and where incubation will take place.

There are open ground nests, nests located in shelters, platform nests and bowls. The first two categories do not have a specific structure, but can be lined with small pebbles, plant debris or the bird's own down, although this is not necessary. The sheltered nest is in a kind of cave, made by the bird itself or otherwise created. Wood ducks use ready-made hollows, woodpeckers themselves hollow them out in tree trunks, and kingfishers dig holes in river banks.

The platform nest is a pile of twigs with a hole in the center for the eggs. Herons and many birds of prey build such nests. The eagles use the same platform year after year, adding new material each season, so that the mass of the structure can ultimately reach more than a ton.

The cup-shaped nests that most songbirds build have a clear structure: they have a dense bottom and walls, and the inside is lined with soft material. Such a nest can lie on a support, like that of blackbirds, hold on to it with its edges, like that of a vireo, or hang in the form of a long wicker bag, like that of an oriole. In some species it is attached to a wall, such as the phoebe and the swift, in a hollow, as in the tree swallow, in a burrow, as in the shore swallow, or on the ground, as in the skylark. The most unusual and large ones include the nests of the pheasant-like Australian ocellated hen. These birds dig deep holes, fill them with plant material, bury their eggs in it and move away; incubation is ensured by the heat released during decay. The hatched chicks independently get out and then live on their own, without knowing their parents.

Construction of a nest.

Tree-nesting songbirds first collect coarse material for the bowl itself, and then finer material for its lining. As it is added, they form a nest, rotating in it with their whole body. In some species, such as the rice troopial, only the female builds the nest; in others, the male supplies her with material for work. In the Western jay, both partners carry out all construction together.

In some species, the male prepares several “preliminary” nests in his area. For example, the house wren often carries sticks to various secluded places, from which the partner chooses one to lay eggs. Great eagle owls use abandoned nests of other birds, and sometimes drive their owners out of newly built ones.

Eggs.

As a general rule, the larger the bird, the larger the eggs it lays, but there are exceptions to this rule. The eggs of brood species, which hatch into downy young that are immediately capable of running and feeding independently, are larger in relation to the mother's body than those of chick species, whose offspring are born naked and helpless. Thus, the eggs of shorebirds are relatively larger than those of songbirds of the same size. In addition, the ratio of egg mass to body mass is often greater in small species than in large ones.

Most birds' eggs are shaped like chicken eggs, but there are many variations here too. In kingfishers they are almost spherical, in hummingbirds they are elongated and blunt at both ends, and in waders they are strongly pointed at one of them.

The surface of the egg can be rough or smooth, matte or shiny, and almost any color from dark purple and green to pure white. In some species it is covered with specks, sometimes forming a corolla around the blunt end. The eggs of many secretly nesting birds are white, and for those that lay them on the ground, the color of the shell often blends in with the background of pebbles or plant debris that lines the nest.

Masonry size.

Once the nest is ready, the female usually lays one egg per day until the clutch is complete. A clutch is the number of eggs laid during one nesting event. Its size varies from one egg in the black-browed albatross to 14 or 15 in some ducks and quails. It also fluctuates within a species. The wandering thrush may lay five eggs in the first clutch of the season, but only 3 or 4 in the second and third. Clutch size is sometimes reduced due to bad weather or lack of food. Most species lay a strictly limited number of eggs; some do not have such certainty: they replace accidentally lost eggs with new ones, bringing the clutch to a standard volume.

Incubation.

Both partners or only one of them can participate in the incubation (incubation) of eggs. Such a bird usually develops one or two brood spots, featherless areas on the underside of the chest. Their highly perfused skin comes into direct contact with the eggs and transfers heat to them. The incubation period, ending with the hatching of the chicks, lasts from 11–12 days for the sparrow to approximately 82 days for the wandering albatross.

Brightly colored males, as a rule, do not sit on eggs if the nest is open. The exception is the Red-breasted Grosbeak, which not only incubates, but also sings. In many partners who alternate incubating eggs, the brooding instinct is so strong that at times one bird pushes the other off the nest to take its place. If only one partner is incubating, he will periodically leave the nest to feed and bathe.

Hatching.

The embryo develops a special growth at the end of the beak - an egg tooth, with the help of which, when hatching approaches, it scrapes the shell from the inside, reducing its strength. Then, resting his feet and wings, he presses cracks in it, i.e. pecks. After pecking, hatching can take from several hours for small birds to several days for larger ones. All this time, the embryo squeaks abruptly, to which the parents respond with increased attention, sometimes pecking at cracks in the shell and tearing off small pieces of it.

Chick.

Songbirds and many other birds are nestling birds: their chicks hatch naked, blind and helpless. Waders, ducks, chickens and some other birds are called brood birds: their chicks are immediately covered with down, are able to walk and provide themselves with food. There are many intermediate variants between the typical nestling and brood species.

Immediately after hatching, typical chick birds are unable to control their body temperature and need to be kept warm by their parents. They can only raise their heads, open their mouths wide and move in the nest when its shaking indicates the arrival of an adult bird. The bright mouths of the chicks serve as signal stimuli for her - “targets for food”, stimulating its delivery exactly to its destination. The parent either passes the food from beak to beak or regurgitates it directly into the throats of the offspring. Pelicans bring fish to the nest in a throat pouch, open their huge beak wide and allow each chick to stick its head in to feed on its own. Eagles and hawks deliver prey in their talons and tear it into pieces, which are fed to their descendants.

Adult birds, having fed the chicks, as a rule, wait for the appearance of their droppings, secreted in a mucous sac, take it away and throw it away. Some species maintain perfect cleanliness in the nest, while others, such as kingfishers, do nothing for this.

Chicks of nestling birds sit in the nest for 10 to 17 days, and after leaving it, they depend on their parents to protect and feed them for at least 10 more days. In species with a long brooding period, the chick remains in the nest longer: in the bald eagle - 10-12 weeks, and in the wandering albatross, the largest of the flying seabirds - approx. 9 months The duration of nesting life is influenced by the degree of its safety. Chicks emerge from open ground nests relatively early.

Contrary to popular belief, parents do not encourage their offspring to live independently. The chick leaves the nest voluntarily, having acquired the necessary coordination of movements. For the first time, the “fledglings” that fluttered out of it do not yet know how to fly properly.

The chicks of brood birds spend much more time in the egg than those of chicks, and when hatching they are usually developed in the same way as those when they leave the nest. As soon as the down has dried, the brood chicks begin to accompany their parents in search of food. They may still need heating for the first few days. These chicks clearly respond to the voice of their parents, “freezing” at the alarm signal and rushing to them in response to an invitation to eat.

However, they quickly learn to get food on their own. An adult bird leads them to the feeding site and can show edible objects, peck them and release them from its beak. However, more often, parents only look after the kids while they learn through trial and error what is suitable for food. Almost immediately after hatching, the noisy plover chicks begin to peck seeds and small insects from the ground, and the ducklings follow their mother into shallow water and begin to dive in search of food.

POPULATIONS

According to ornithologists, there are approx. 100 billion birds of approximately 8600 species. The number of individuals of a single species varies from a few dozen, such as the critically endangered whooping crane, to many millions, such as the Wilson's storm petrel, an oceanic bird that may be the world's largest wild bird.

Fertility and mortality.

Population size, i.e. the totality of individuals of a species in a given territory depends on the levels of fertility and mortality. When these parameters are approximately equal (as they usually are), the population remains stable. If the birth rate exceeds the death rate, the population grows, otherwise it declines.

Fertility is determined by the number of eggs laid during the year and the success of hatching. In birds that lay one egg every two years, like the California condor, each pair adds only “half an individual” to the population per year, and on the contrary, species with 2–3 large clutches annually can increase it by 20 individuals over the same period .

Lifespan.

Under ideal conditions, many species, especially large ones, live very long lives. For example, some eagles, vultures and parrots in captivity reached the age of 50–70 years. However, in nature the bird's lifespan is much shorter. According to data obtained through banding, large birds potentially live longer than small ones. The maximum recorded ages for some birds in the wild are: gulls and waders - 36 years, terns - 27 years, hawks - 26 years, loons - 24 years, ducks, geese and swans - 23 years, swifts - 21 years and woodpeckers - 12 years . It is likely that predators such as condors and eagles, as well as large albatrosses, live longer.

Population density.

Populations tend to maintain their characteristic density for a long time, i.e. number of individuals per unit area. A catastrophe that wipes out a significant portion of a population is often followed by a significant reduction in mortality, and its size quickly recovers. For example, a harsh winter, which many birds do not survive, is typically followed by a spring and summer with unusually high chick survival rates. This is largely due to the fact that the few surviving individuals have plenty of food and convenient nesting places.

Another important factor regulating population size is the territory available to it. Each pair needs a certain size area of ​​suitable habitat for nesting. After the pairs have occupied all the space suitable for the species, not a single one of their relatives can settle there anymore. “Excess” birds either have to nest in unfavorable conditions or not breed at all.

When food resources are scarce and the population density is high, its size is usually limited by competition for food. It is apparently strongest at the end of winter and between individuals of the same species, since they all need the same diet.

In overpopulated areas, competition for food can lead to emigration, which reduces the population density in a given area. Individuals of some species, such as snowy owls, in years with high numbers, a lack of food resources, or both, appear en masse outside their normal range.

Although predation is the most prominent cause of bird mortality, it has a much weaker effect on population size than unfavorable environmental conditions. The victims of predators are usually individuals weakened by old age or disease.

MIGRATIONS

Flight allowed birds to adapt better than many animals to changing environmental factors, in particular periodic fluctuations in meteorological conditions, food availability and other parameters. The birds may have begun seasonal migrations in the Northern Hemisphere during the Ice Age, when the southward advance of the glacier pushed them southward during the colder months, but melting ice allowed them to return to their parents' breeding grounds in the summer. It could also be that some species, under the influence of fierce interspecific competition in tropical areas during the retreat of the glacier, began to temporarily migrate north to nest in a less densely populated environment. In any case, for many modern birds, migrating closer to the equator in the fall and back in the spring is an integral species characteristic.

Synchronization.

Migration is synchronized with the season and breeding cycle; it will not occur until the bird is physiologically ready for it and receives the appropriate external stimulus. Before migrating, the bird eats a lot, gaining weight and storing energy in the form of subcutaneous fat. Gradually she comes into a state of “migratory restlessness.” In spring, it is stimulated by lengthening daylight hours, which activates the gonads (sex glands), changing the functioning of the pituitary gland. In autumn, the bird reaches the same state as the length of the day decreases, which causes depression of gonadal function. In order for an individual ready to migrate to set off, it needs a special external stimulus, such as a change in the weather. This stimulus is provided by the movement of a warm atmospheric front in the spring and a cold one in the fall.

During migration, most birds fly at night, when they are less threatened by winged predators, and devote the day to feeding. Both single-species and mixed flocks, family groups and single individuals travel. Birds usually take their time on the road, spending several days or even a week in a favorable place.

Flyways.

Many birds have short journeys. Mountain species descend lower until they find enough food; spruce crossbills fly to the nearest area with a good harvest of cones. However, some birds migrate vast distances. The Arctic tern has the longest flight path: every year it flies from the Arctic to the Antarctic and back, covering at least 40,000 km in both directions.

Speed

migration depends on the species. A flock of waders can reach speeds of up to 176 km/h. The rockfish flies 3,700 km south, making an average of 920 km per day. Flight speed measurements using radar have shown that most small birds fly between 21 and 46 km/h on calm days; larger birds, such as ducks, hawks, falcons, waders and swifts, fly faster. The flight is characterized by a constant, but not maximum speed for the species. Since it takes more energy to overcome a headwind, birds tend to wait it out.

In the spring, species migrate north as if on a schedule, reaching certain points at the same time from year to year. Lengthening the non-stop flight segments as they approach the target, they cover the last few hundred kilometers at a much faster speed.

Heights.

As radar measurements show, the altitude at which the flight takes place varies so greatly that it is impossible to talk about any normal or average values. However, night migrants are known to fly higher than those traveling during the day. Among migratory birds recorded over the Cape Cod Peninsula (USA, Massachusetts) and the nearest ocean, 90% stayed at an altitude of less than 1500 m.

Night migrants tend to fly higher in overcast conditions because they tend to fly above the clouds rather than below or through them. However, if the clouds extend to high altitudes at night, birds may fly under them. At the same time, they are attracted to tall, illuminated buildings and lighthouses, which sometimes leads to deadly collisions.

According to radar measurements, birds rarely rise above 3000 m. However, some migrants reach amazing heights. In September, birds were recorded flying over the south-eastern part of England at approx. 6300 m. Radar tracking and observation of silhouettes crossing the disk of the moon have shown that nocturnal migrants, as a rule, do not “attach” to the landscape in any way. Birds flying during the day tend to follow land landmarks elongated from north to south - mountain ranges, river valleys and long peninsulas.

Navigation.

As experiments have shown, birds have several instinctive methods to determine the direction of migration. Some species, such as the starling, use the sun as a guide. Using an “internal clock”, they maintain a given direction, making corrections for the constant displacement of the star above the horizon. Night migrants are guided by the position of bright stars, in particular the Big Dipper and the North Star. Keeping them in sight, birds instinctively fly north in the spring and away from it in the fall. Even when dense clouds reach high altitudes, many migrants are able to maintain the right direction. They may be using wind direction or familiar terrain features if they are visible. It is unlikely that any species is guided when navigating by a single environmental factor.

MORPHOLOGY

Morphology usually refers to the external structure of an animal, as opposed to the internal structure, which is usually called anatomical.

Beak

the bird consists of the upper and lower jaws (beak and mandible), covered with horny sheaths. Its shape depends on the method of obtaining food characteristic of the species, and therefore makes it possible to judge the feeding habits of the bird. The beak can be long or short, curved up or down, spoon-shaped, serrated or with crossed jaws. In almost all birds, it is worn off at the end from consumption, and its horny cover must be continuously renewed.

Most species have a black beak. However, there are a variety of variations in its color, and in some birds, such as puffins and toucans, this is the brightest part of the body.

Eyes

in birds they are very large, because these animals navigate mainly with the help of vision. The eyeball is mostly hidden under the skin, with only the dark pupil surrounded by a colored iris visible.

In addition to the upper and lower eyelids, birds also have a “third” eyelid – the nictitating membrane. This is a thin, transparent fold of skin that moves over the eye from the side of the beak. The nictitating membrane moisturizes, cleanses and protects the eye, instantly closing it in case of danger of contact with an external object.

ear holes,

located behind and just below the eyes, in most birds they are covered with feathers of a special structure, the so-called. ear coverts. They protect the ear canal from foreign objects getting inside, while at the same time not interfering with the propagation of sound waves.

Wings

Birds are long or short, rounded or sharp. In some species they are very narrow, while in others they are wide. They can also be concave or flat. As a rule, long narrow wings serve as an adaptation for long flights over the sea. Long, wide and rounded wings are well adapted to soaring in rising currents of air heated near the ground. Short, rounded and concave wings are most convenient for slow flight over fields and among forests, as well as for quickly rising into the air, for example, in times of danger. Pointed flat wings promote rapid flapping and rapid flight.

Tail

as a morphological section, it consists of tail feathers that form its posterior edge, and covert feathers that overlap their bases. The tail feathers are paired, they are located symmetrically on both sides of the tail. The tail can be longer than the rest of the body, but sometimes it is practically absent. Its shape, characteristic of different birds, is determined by the relative length of the various tail feathers and the characteristics of their tips. As a result, the tail can be rectangular, rounded, pointed, forked, etc.

Legs.

In most birds, the part of the leg free from feathers (foot) includes the tarsus, fingers and claws. In some species, such as owls, the tarsus and fingers are feathered; in a few others, in particular swifts and hummingbirds, they are covered with soft skin, but usually there is a hard horny covering, which, like all skin, is continuously renewed. This cover can be smooth, but more often it consists of scales or small irregularly shaped plates. In pheasants and turkeys, there is a horny spur on the back of the tarsus, and in the collared hazel grouse, on the sides of the toes there is a rim of horny spines, which falls off in the spring and grows back in the fall to serve as skis in the winter. Most birds have 4 toes on their feet.

Fingers are designed differently depending on the habits of the species and their environment. For grasping branches, climbing, catching prey, carrying food and manipulating it, they are equipped with steeply curved sharp claws. In running and burrowing species, the fingers are thick, and the claws on them are strong, but rather blunt. Waterfowl have webbed toes, like ducks, or leathery blades on the sides, like grebes. In larks and some other open-space singing species, the hind finger is armed with a very long claw.

Other signs.

Some birds have a bare head and neck or are covered with very sparse feathers. The skin here is usually brightly colored and forms outgrowths, for example, a ridge on the crown and earrings on the throat. Often, clearly visible bumps are located at the base of the upper jaw. Typically, these features are used for demonstrations or simpler communication signals. In carrion-eating vultures, the bare head and neck are probably an adaptation that allows them to feed on rotting carcasses without soiling their feathers in very inconvenient areas of the body.

ANATOMY AND PHYSIOLOGY

When birds acquired the ability to fly, their internal structure changed greatly compared to the ancestral structure characteristic of reptiles. To reduce the weight of the animal, some organs became more compact, others were lost, and scales were replaced by feathers. Heavier, vital structures have moved closer to the center of the body to improve its balance. In addition, the efficiency, speed and controllability of all physiological processes increased, which provided the power required for flight.

Skeleton

birds are characterized by remarkable lightness and rigidity. Its relief was achieved thanks to the reduction of a number of elements, especially in the limbs, and the appearance of air cavities inside certain bones. Rigidity is provided by the fusion of many structures.

For convenience of description, the axial skeleton and the skeleton of the limbs are distinguished. The first includes the skull, spine, ribs and sternum. The second is formed by the arcuate shoulder and pelvic girdles and the bones of the free limbs attached to them - the anterior and posterior.

Scull.

The skull of birds is characterized by huge eye sockets, corresponding to the very large eyes of these animals. The braincase is adjacent to the eye sockets at the back and is, as it were, pressed by them. Strongly protruding bones form toothless upper and lower jaws, corresponding to the beak and mandible. The ear opening is located under the lower edge of the orbit almost close to it. Unlike the upper jaw of humans, in birds it is mobile due to a special hinge attachment to the braincase.

Spine,

or the spinal column is made up of many small bones called vertebrae, which are arranged in a row from the base of the skull to the tip of the tail. In the cervical region they are isolated, mobile and at least twice as numerous as in humans and most mammals. As a result, the bird can bend its neck and turn its head in almost any direction. In the thoracic region, the vertebrae are articulated with the ribs and, as a rule, firmly fused to each other, and in the pelvic region they are fused into a single long bone - the complex sacrum. Thus, birds are characterized by an unusually stiff back. The remaining vertebrae - the caudal - are mobile, with the exception of the last few, which are fused into a single bone, the pygostyle. It resembles the shape of a plowshare and serves as a skeletal support for the long tail feathers.

Rib cage.

The ribs, together with the thoracic vertebrae and sternum, surround and protect the outside of the heart and lungs. All flying birds have a very wide sternum, growing into a keel for attachment of the main flight muscles. As a rule, the larger it is, the stronger the flight. Completely flightless birds have no keel.

Shoulder girdle,

connecting the forelimb (wing) to the axial skeleton, it is formed on each side by three bones arranged like a tripod. One of its legs, the coracoid (crow's bone), rests on the sternum, the second, the scapula, lies on the ribs, and the third, the collarbone, is fused with the opposite collarbone in the so-called. fork. The coracoid and the scapula, where they meet each other, form the glenoid cavity in which the head of the humerus rotates.

Wings.

The bones in a bird's wing are basically the same as those in the human hand. The humerus, the only bone in the upper limb, is articulated at the elbow joint with two bones of the forearm - the radius and ulna. Below, i.e. in the hand, many elements present in humans are fused together or lost in birds, so that only two wrist bones remain, one large metacarpal bone, or buckle, and 4 phalangeal bones, corresponding to three fingers.

The wing of a bird is significantly lighter than the forelimb of any terrestrial vertebrate of similar size. And the point is not only that the hand includes fewer elements - the long bones of the shoulder and forearm are hollow, and in the shoulder there is a special air sac related to the respiratory system. The wing is additionally lightened by the absence of large muscles. Instead, its main movements are controlled by the tendons of the highly developed musculature of the sternum.

The flight feathers extending from the hand are called large (primary) flight feathers, and those attached in the area of ​​the ulna bone of the forearm are called small (secondary) flight feathers. In addition, three more wing feathers are distinguished, attached to the first finger, and covert feathers, smoothly, like tiles, overlapping the bases of the flight feathers.

Pelvic girdle

on each side of the body it consists of three bones fused together - the ischium, pubis and ilium, the latter fused with the complex sacrum. All this together protects the outside of the kidney and ensures a strong connection of the legs with the axial skeleton. Where the three bones of the pelvic girdle meet each other is the deep acetabulum, in which the head of the femur rotates.

Legs.

In birds, as in humans, the femur forms the core of the upper part of the lower limb, the thigh. The tibia is attached to this bone at the knee joint. While in humans it consists of two long bones, the tibia and fibula, in birds they are fused with each other and with one or more upper tarsal bones into an element called the tibiotarsus. Of the fibula, only a thin short rudiment remains visible, adjacent to the tibiotarsus.

Foot.

In the ankle (more precisely, intratarsal) joint, the foot is attached to the tibiotarsus, consisting of one long bone, the tarsus, and the bones of the fingers. The tarsus is formed by elements of the metatarsus, fused together and with several lower tarsal bones.

Most birds have 4 fingers, each of which ends in a claw and is attached to the tarsus. The first finger is facing backwards. In most cases, the rest are directed forward. In some species, the second or fourth toe faces backward along with the first. In swifts, the first toe is directed forward, like the others, but in ospreys it is capable of turning in both directions. In birds, the tarsus does not rest on the ground, and they walk on their toes with their heels lifted off the ground.

Muscles.

The wings, legs and the rest of the body are driven by approximately 175 different skeletal striated muscles. They are also called arbitrary, i.e. their contractions can be controlled “consciously” by the brain. In most cases they are paired, symmetrically located on both sides of the body.

Flight is provided mainly by two large muscles, the pectoral and supracoracoid. They both start on the sternum. The pectoral muscle, the largest, pulls the wing down and thereby causes the bird to move forward and upward in the air. The supracoracoid muscle pulls the wing upward, preparing it for the next stroke. In domestic chicken and turkey, these two muscles represent the "white meat" and the rest correspond to the "dark meat".

In addition to skeletal muscles, birds have smooth muscles that lie in layers in the walls of the organs of the respiratory, vascular, digestive and genitourinary systems. Smooth muscles are also found in the skin, where they cause the movements of feathers, and in the eyes, where they provide accommodation, i.e. focusing the image on the retina. They are called involuntary because they work without “volitional control” from the brain.

Nervous system.

The central nervous system consists of the brain and spinal cord, which in turn are formed by many nerve cells (neurons).

The most prominent part of the bird's brain is the cerebral hemispheres, which are the center of higher nervous activity. Their surface is smooth, without grooves and convolutions characteristic of many mammals, its area is relatively small, which correlates well with the relatively low level of “intelligence” of birds. Inside the cerebral hemispheres there are centers for coordination of instinctive forms of activity, including feeding and singing.

The cerebellum, which is of particular interest in birds, is located directly behind the cerebral hemispheres and is covered with grooves and convolutions. Its complex structure and large size correspond to the difficult tasks associated with maintaining balance in the air and coordinating the many movements necessary for flight.

The cardiovascular system.

Birds have larger hearts than mammals of similar body size, and the smaller the species, the relatively larger its heart. For example, in hummingbirds its mass accounts for up to 2.75% of the mass of the entire organism. All birds that fly frequently must have a large heart to ensure rapid blood circulation. The same can be said for species that live in cold areas or at high altitudes. Like mammals, birds have a four-chambered heart.

The frequency of contractions correlates with its size. So, in a resting African ostrich, the heart makes approx. 70 “beats” per minute, and in a hummingbird in flight - up to 615. Extreme fright can increase the bird’s blood pressure so much that large arteries burst and the individual dies.

Like mammals, birds are warm-blooded, and the range of normal body temperatures is higher than that of humans - from 37.7 to 43.5 ° C.

Birds' blood typically contains more red blood cells than most mammals and, as a result, can carry more oxygen per unit of time, which is necessary for flight.

Respiratory system.

In most birds, the nostrils lead into the nasal cavities at the base of the beak. However, cormorants, gannets and some other species lack nostrils and are forced to breathe through their mouths. Air entering the nostrils or mouth is directed to the larynx, from which the trachea begins. In birds (unlike mammals), the larynx does not produce sounds, but forms only a valve apparatus that protects the lower respiratory tract from food and water entering them.

Near the lungs, the trachea divides into two bronchi entering them, one for each. At the point of its division is the lower larynx, which serves as the vocal apparatus. It is formed by expanded ossified rings of the trachea and bronchi and internal membranes. Pairs of special singing muscles are attached to them. When air exhaled from the lungs passes through the lower larynx, it causes the membranes to vibrate, producing sounds. Birds with a wide range of vocal tones have more singing muscles that strain the vocal membranes than do poorly singing species.

Upon entering the lungs, each bronchus divides into thin tubes. Their walls are penetrated by blood capillaries that receive oxygen from the air and release carbon dioxide into it. The tubes lead into thin-walled air sacs that resemble soap bubbles and are not penetrated by capillaries. These bags are found outside the lungs - in the neck, shoulders and pelvis, around the lower larynx and digestive organs, and also penetrate into the large bones of the limbs.

The inhaled air moves through the tubes and enters the air sacs. When you exhale, it goes out of the bags again through the tubes through the lungs, where gas exchange again occurs. This double breathing increases the body's supply of oxygen, which is necessary for flight.

Air sacs also serve other functions. They humidify the air and regulate body temperature, allowing surrounding tissues to lose heat through radiation and evaporation. Thus, birds seem to sweat from the inside, which compensates for their lack of sweat glands. At the same time, the air sacs ensure the removal of excess fluid from the body.

Digestive system,

in principle, it is a hollow tube extending from the beak to the cloaca opening. It takes in food, secretes juice with enzymes that break down food, absorbs the resulting substances and removes undigested residues. Although the structure of the digestive system and its functions are basically the same in all birds, there are differences in details associated with the specific feeding habits and diet of a particular group of birds.

The digestion process begins when food enters the mouth. Most birds have salivary glands that secrete saliva, which moistens the food and begins to digest it. The salivary glands of some swiftlets secrete a sticky fluid used to build nests.

The shape and functions of the tongue, like the beak, depend on the bird’s lifestyle. The tongue can be used to hold food, manipulate it in the mouth, feel and taste.

Woodpeckers and hummingbirds can extend their unusually long tongues well beyond their beaks. In some woodpeckers, it has rear-facing barbs at the end that help pull insects and their larvae out of holes in the bark. In hummingbirds, the tongue is usually forked at the end and curled into a tube for sucking nectar from flowers.

From the mouth, food passes into the esophagus. In turkeys, grouse, pheasants, pigeons and some other birds, part of it, called the crop, is constantly expanded and serves to store food. In many birds, the entire esophagus is quite distensible and can temporarily accommodate a significant amount of food before it enters the stomach.

The latter is divided into two parts - glandular and muscular (“navel”). The first secretes gastric juice, which begins to break down food into substances suitable for absorption. The “navel” is distinguished by thick walls with hard internal ridges that grind food obtained from the glandular stomach, which compensates for the birds’ lack of teeth. In species that eat seeds and other solid foods, the muscle walls of this section are especially thick. In many birds of prey, flat round pellets are formed in the muscular stomach from indigestible parts of food, in particular bones, feathers, hair and hard parts of insects, which are periodically regurgitated.

After the stomach, the digestive tract continues with the small intestine, where food is finally digested. The large intestine in birds is a short, straight tube leading to the cloaca, where the ducts of the genitourinary system also open. Thus, fecal matter, urine, eggs and sperm enter it. All these products exit the body through a single opening.

Genitourinary system.

This complex consists of closely interconnected excretory and reproductive systems. The first operates continuously, and the second is activated at certain times of the year.

The excretory system includes two kidneys, which remove waste products from the blood and form urine. Birds do not have a bladder, and the water passes through the ureters directly into the cloaca, where most of the water is absorbed back into the body. The white, mushy residue is eventually expelled along with the dark-colored feces coming from the colon.

The reproductive system consists of the gonads, or sex glands, and the tubes extending from them. Male gonads are a pair of testes in which male reproductive cells (gametes) - sperm are formed. The shape of the testes is oval or elliptical, with the left one usually being larger. They lie in the body cavity near the anterior end of each kidney. Before the onset of the breeding season, the stimulating effect of pituitary hormones causes the testes to enlarge hundreds of times. A thin convoluted tube, the vas deferens, carries sperm from each testis into the seminal vesicle. There they accumulate until ejaculation occurs at the moment of copulation, during which they exit into the cloaca and through its opening to the outside.

The female gonads, the ovaries, form female gametes - eggs. Most birds have only one ovary, the left one. Compared to a microscopic sperm, an egg is huge. Its main part by weight is the yolk - the nutritious material for the developing embryo after fertilization. From the ovary, the egg enters a tube called the oviduct. The muscles of the oviduct push it past various glandular areas in its walls. They surround the yolk with albumen, shell membranes, a hard calcium-containing shell, and finally add shell-coloring pigments. The transformation of the oocyte into an egg ready for laying takes approx. 24 hours

Fertilization in birds is internal. Sperm enter the female's cloaca during copulation and swim up the oviduct. Fertilization, i.e. the fusion of male and female gametes occurs at its upper end before the egg is covered with protein, soft membranes and shell.

FEATHERS

Feathers protect the bird's skin, provide thermal insulation of its body, since they hold a layer of air near it, streamline its shape and increase the area of ​​load-bearing surfaces - wings and tail.

Almost all birds appear fully feathered; Only the beak and feet appear partially or completely naked. However, the study of any species capable of flight reveals that feathers grow from rows of depressions - feather bags, grouped into wide stripes, pterilia, which are separated by bare areas of skin, apteria. The latter are invisible, since they are covered by overlapping feathers from adjacent pterilia. Only a few birds have feathers that grow evenly throughout their body; These are usually flightless species such as penguins.

Feather structure.

The primary flight feather of the wing is the most complex. It consists of an elastic central rod to which two wide flat fans are attached. Internal, i.e. facing the center of the bird, the fan was wider than the outer one. The lower part of the rod, the edge, is partially immersed in the skin. The stem is hollow and free from the webs attached to the upper part of the rod - the trunk. It is filled with a cellular core and has a longitudinal groove on the underside. Each fan is formed by a number of parallel grooves of the first order with branches, the so-called. grooves of the second order. On the latter there are hooks that hook into adjacent second-order grooves, connecting all the elements of the fan into a single whole - using the zipper mechanism. If the second-order grooves are unfastened, the bird only needs to smooth the feather with its beak to “fasten” it again.

Types of feathers.

Almost all easily visible feathers are arranged as described above. Since they are the ones that give the bird’s body its external outline, they are called contour lines. In some species, such as grouse and pheasants, a small side feather of a similar structure extends from the lower part of their shaft. It is very fluffy and improves thermal insulation.

In addition to contour feathers, birds have feathers of a different structure on their bodies. The most common fluff consists of a short shaft and long flexible barbs that do not interlock. It protects the body of chicks, and in adult birds it is hidden under the contour feathers and improves thermal insulation. There are also down feathers that serve the same purpose as down. They have a long shaft, but non-jointed barbules, i.e. in structure they occupy an intermediate position between contour feathers and down.

Scattered among the contour feathers and usually hidden by them are thread-like feathers, clearly visible on a plucked chicken. They consist of a thin rod with a small rudimentary fan at the top. Thread-like feathers extend from the bases of the contour feathers and perceive vibrations. It is believed that these are sensors of external forces that are involved in stimulating the muscles that control large feathers.

The bristles are very similar to thread-like feathers, but are stiffer. They stick out in many birds near the corners of the mouth and probably serve for touch, like the whiskers of mammals.

The most unusual feathers are the so-called. powdery down located in special zones - powderets - under the main plumage of herons and bitterns, or scattered throughout the body of pigeons, parrots and many other species. These feathers grow continuously and crumble into fine powder at the top. It has water-repellent properties and, probably, together with the secretion of the coccygeal gland, protects the contour feathers from wetting.

The shape of contour feathers is very diverse. For example, the edges of owls' flight feathers are fluffed, which makes the flight almost silent and allows you to approach prey unnoticed. The bright and unusually long feathers of birds of paradise in New Guinea serve as “decoration” for displays.

Shedding.

Feathers are dead structures that cannot repair themselves, so they need to be replaced periodically. The loss of old feathers and the growth of new ones in their place is called molting.

Most birds moult, replacing all their feathers, at least once a year, usually in late summer before fall migration. Another molt, observed in many species in the spring, is usually partial and affects only the body feathers, leaving the flight feathers and tail feathers in place. As a result of molting, males acquire a bright mating plumage.

Shedding occurs gradually. Not a single pterilium loses all its feathers at once. In most flying birds, flight and tail feathers are replaced in a certain sequence. Thus, some of them are already growing back while others are falling out, so the ability to fly is maintained throughout the entire molt. Only a few groups of flying birds, and exclusively aquatic ones, shed all their flight feathers at the same time.

The entire set of feathers of a bird at a given time is called its plumage, or plumage. During its life, the individual changes several types of plumage as a result of molting. The first of these is natal down, which is already present at the time of hatching. The next type of plumage is juvenile, i.e. corresponding to immature individuals.

In most birds, juvenile plumage is replaced directly by adult plumage, but some species have two or three more intermediate appearance options. For example, only at the age of seven does a bald eagle acquire a typical adult appearance with a pure white head and tail.

Feather care.

All birds clean their plumage (this is called “prining”), and most also bathe. Swallows, swifts and terns plunge into the water several times in a row while flying. Other birds, standing or crouching in shallow water, shake their fluffy feathers, trying to moisten them evenly. Some forest species bathe in rainwater or dew accumulated on the leaves. Birds dry themselves by fluffing and shaking their feathers, cleaning them with their beaks and flapping their wings.

Birds lubricate themselves with oil secreted by the coccygeal gland at the base of the tail. They use their beaks to apply it to their feathers, thereby making them water-repellent and more elastic. To lubricate the plumage of their heads, birds use their beaks to rub their legs with fat and then scratch their heads with them.

The color of feathers is determined by both chemicals (pigments) and structural features. Carotenoid pigments produce red, orange and yellow colors. Another group, melanins, gives black, gray, brown or brown-yellow color depending on the concentration. “Structural colors” are due to the characteristics of absorption and reflection of light waves that are independent of pigments.

Structural coloring can be iridescent (rainbow) or monochromatic. In the latter case, it is usually white and blue. A feather is perceived as white if it is almost or completely devoid of pigment, transparent, but due to its complex internal structure it reflects all light waves of the visible spectrum. It appears blue if it contains densely packed cells with brown pigment under a transparent shell. They absorb all light passing through the transparent layer, with the exception of blue rays, which are reflected by them. There is no blue pigment in the feather as such.

The iridescent color, which changes depending on the viewing angle, is mainly due to the mutual overlap of peculiarly expanded, twisted and black melanin-containing second-order beards. Thus, American grackle birds look either multi-colored or black. The throat patch of the common ruby-throated hummingbird alternates between flashing bright red and appearing brownish-black.

Pattern.

For no other group of living beings is body color as important as for birds. It can be cryptic or protective if it imitates the surrounding background, making the individual invisible. This is especially common in females; as a result, sitting motionless on the eggs, they do not attract the attention of predators. However, sometimes both sexes are cryptically colored.

Many birds living among grass have a pattern of longitudinal stripes. In addition, they often have relatively dark tops and lighter bottoms. Since the light falls from above, the lower parts of the body are shaded and approach the color of the upper parts, and as a result the whole bird looks flat and does not stand out from the surrounding background.

In other cases, the coloring is disjunctive, i.e. consisting of irregularly shaped, clearly defined contrasting spots, which “breaks” the contours of the body into parts that seem unrelated to each other and do not resemble a living creature. Waders painted this way, such as the turnstone and the noisy plover, are almost invisible against the backdrop of a shingle beach.

Conversely, some birds are characterized by bright markings on the tail, body and wings that “flare up” during flight. Examples include the white tail feathers of the junco, the white body of the avoc-billed woodpecker, and the white wing stripes of the dusky nightjar. Bright markings play a protective role. Suddenly “flashing up” in front of an attacking predator, they momentarily frighten it, giving the bird additional time to escape; and can also distract the enemy's attention from the most important parts of the body. In addition, the clearly visible coloration of the adult is important when the bird pretends to be wounded, luring a predator away from the nest or chick. It is likely that bright spots also contribute to intraspecific recognition, acting as signal stimuli that strengthen the bond between members of the flock.

The color pattern helps to find a sexual partner during the breeding season. Typically, brighter and more contrasting colors are characteristic of males, who use them during mating displays.

FEEDING HABITS

For the most part, birds are either predators, feeding on other animals, or phytophages, eating plant material. Only relatively few species are omnivores, i.e. consume almost any food.

Most birds of prey are strictly carnivorous; they hunt a wide variety of animals, including amphibians, reptiles, birds and beasts. This category also includes vultures, which feed exclusively on carrion. Ospreys and many aquatic birds are also fish-eating predators, and many small birds eat insects, spiders, earthworms, slugs and other invertebrates. Strictly herbivorous species include grass-grazing African ostriches and geese.

Only a few birds have a specialized diet. For example, the social slug-eating kite eats exclusively snails of the genus Pomacea. The strongly curved beak of this bird is well adapted for removing the body of a mollusk from a shell, but is of little use for any other operations.

Many species change their diet depending on the season, climate, location, and also with age. During the winter in the southern United States, up to 90% of the savannah bunting's food is of plant origin, and in the summer, after migrating north, it contains up to 75% of insects. Immediately after hatching, chicks of almost all species consume animal food. Most songbirds feed primarily on insects, although as adults they can switch almost entirely to seeds or other plant foods.

Some species store food, usually in the fall, for use in the winter when food is scarce. For example, nuthatches and woodpeckers hide nuts in cracks in the bark, and the European nutcracker ( Nucifraga caryocatactes) buries them in the ground. Studies of the latter species have shown that the bird finds up to 86% of its underground reserves even under a layer of snow 25 cm thick.

African honeyguides “lead” a person or honeyeater from the mustelid family to a bee nest, flying from branch to branch, calling invitingly and waving their tail. When the mammal opens the nest to get to the honey, the bird feasts on the wax honeycomb.

The herring gull is an omnivorous species, sometimes including bivalves in its diet. To break their tough shells, the bird lifts the prey high into the air and drops it onto a hard surface such as a rock ledge or a highway.

At least two species of birds use tools to obtain food. One of them is the woodpecker finch ( Cactospiza pallida), already mentioned above, and the second is the common vulture ( Neophron percnopterus) from Africa, which takes a large stone in its beak and drops it on the egg of an African ostrich.

Some species take food from other birds. Frigates and skuas are considered notorious pirates; they attack other seabirds, forcing them to abandon their prey.

The most characteristic method of locomotion in birds is flight. However, birds are, to varying degrees, adapted to moving on land, and some of them are excellent swimmers and divers.

In the air.

The structure of a bird's wing, in principle, ensures the movement of the body in the air. The unfolded wing thins from a thick and rounded leading edge with a skeletal support inside towards the trailing edge formed by the flight feathers. Its upper side is slightly convex, and its lower side is concave.

During normal flapping flight, the pressure of the oncoming air flow acts on the lower surface of the inner half of the wing, which is inclined with the trailing edge down. By deflecting it down, the wing provides lift.

The outer half of the wing describes a semicircle in flight, moving forward and down, and then up and back. The first movement pulls the bird forward, and the second serves as a swing. During the swing, the wing is semi-folded and the flight feathers are spread apart to reduce air pressure on its upper side. Those with short and wide wings must flap them frequently in flight, since their area is small compared to body weight. A long narrow wing does not require a high flapping frequency.

There are three types of flight: gliding, soaring and flapping. Gliding is simply a smooth downward movement on extended wings. Soaring is essentially the same as gliding, but without the loss of altitude. Soaring flight can be dynamic or static. In the first case, this is planning in rising air currents, in which the effect of gravity is compensated by the pressure of rising air. As a result, the bird flies without literally moving its wings. Buzzards, eagles and other large broad-winged species even migrate along meridian mountain ridges using the vertical component of the wind as it slants up the windward slope.

Dynamic soaring is gliding in horizontal air currents that differ in speed and height with an alternating transition between them up and down. Such a flight is typical, for example, of albatrosses, which spend most of their lives above stormy seas.

The flapping flight already described is the main method of locomotion for all birds when taking off, landing and moving in a straight line. Individuals setting off from a high perch simply throw themselves down in order to gain enough speed to fly while falling. When taking off from land or water, the bird, quickly moving its legs, accelerates against the wind until it gains enough speed to lift off the surface. However, if there is no wind or it is impossible to accelerate, it gives its body the necessary impulse through forced wing flaps.

The bird must slow down before landing. To do this, it orients its body vertically and brakes, spreading its wings and tail wide to increase air resistance. At the same time, she extends her legs forward to absorb the impact of the perch or the ground. When landing on water, the bird does not have to slow down much, since the risk of injury is much less.

The tail complements the load-bearing surface of the wings and is used as a brake, but its main function is to serve as a rudder during flight.

Birds can perform special aerial maneuvers according to their specific adaptations. Some, quickly flapping their wings, hover motionless in one place. Others alternate the "spurts" of flapping flight with periods of gliding, which makes the flight undulating.

On the land.

Birds are thought to have evolved from arboreal reptiles. They probably inherited from them the habit of jumping from branch to branch, characteristic of most birds. At the same time, some birds, such as woodpeckers and pikas, acquired the ability to climb vertical tree trunks using their tails as support.

Having descended from the trees to the ground during evolution, many species gradually learned to walk and run. However, development in this direction proceeded differently in different species. For example, a wandering thrush can both jump and walk, while a starling normally only walks. The African ostrich runs at speeds of up to 64 km/h. On the other hand, swifts are unable to jump or run and use their weak legs only to cling to vertical surfaces.

Birds that walk in shallow waters, such as herons and stilts, have long legs. Birds that walk on carpets of floating leaves and bogs are characterized by long fingers and claws to prevent them from falling through. Penguins have short, thick legs located far behind their center of gravity. For this reason, they can only walk with their body upright and in short steps. If it is necessary to move faster, they lie on their bellies and glide, as if on a sleigh, pushing off the snow with flipper-like wings and legs.

In water.

Birds are originally land creatures and always nest on land or, in rare cases, on rafts. However, many of them have adapted to an aquatic lifestyle. They swim by alternating strokes with their legs, usually equipped with membranes or blades on their toes that act like oars. The wide body provides waterfowl with stability, and their dense feather cover contains air, increasing buoyancy. The ability to swim is usually necessary for birds that forage underwater. Swans, geese and some ducks in shallow waters practice partial diving: turning their tail up and stretching their neck down, they get food from the bottom.

Gannets, pelicans, terns and other fish-eating species dive into the water in summer, with the height of the fall depending on the size of the bird and the depth they seek to reach. Thus, heavy gannets, falling like a stone from a height of 30 m, plunge into the water to 3–3.6 m. Light-bodied terns dive from a lower height and plunge only a few centimeters.

Penguins, loons, grebes, diving ducks and many other birds dive from the surface of the water. Lacking the inertia of diving divers, they use the movements of their legs and (or) wings to dive. In such species, the legs are usually located at the rear end of the body, like a propeller under the stern of a ship. When diving, they can reduce buoyancy by pressing their feathers tightly and squeezing their air sacs. Probably for most birds the maximum diving depth from the surface of the water is close to 6 m. However, the dark-billed loon can dive to 18 m, and the long-tailed diving duck to approximately 60 m.

SENSE ORGANS

In order to see well enough during fast flight, birds have better vision than all other animals. Their hearing is also well developed, but the sense of smell and taste in most species is weak.

Vision.

Birds' eyes have a number of structural and functional features that correlate with their lifestyle. Particularly noticeable is their large size, which provides a wide field of view. In some birds of prey they are much larger than in humans, and in the African ostrich they are larger than in the elephant.

Accommodation of the eyes, i.e. In birds, their adaptation to a clear vision of objects when the distance to them changes occurs with amazing speed. A hawk pursuing prey continuously keeps it in focus until the very moment of capture. A bird flying through a forest must clearly see the branches of surrounding trees so as not to collide with them.

There are two unique structures present in the bird's eye. One of them is the ridge, a fold of tissue that protrudes into the inner chamber of the eye from the side of the optic nerve. Perhaps this structure helps detect movement by casting a shadow on the retina when the bird moves its head. Another feature is the bony scleral ring, i.e. a layer of small lamellar bones in the wall of the eye. In some species, especially raptors and owls, the scleral ring is so highly developed that it gives the eye a tube shape. This moves the lens away from the retina, and as a result the bird is able to distinguish prey at a great distance.

In most birds, the eyes are tightly fixed in the sockets and cannot move in them. However, this disadvantage is compensated by the extreme mobility of the neck, which allows you to turn your head in almost any direction. In addition, the bird has a very wide overall field of vision because its eyes are located on the sides of its head. This type of vision, in which any object is visible with only one eye at a time, is called monocular. The total field of monocular vision is up to 340°. Binocular vision, with both eyes facing forward, is unique to owls. Their total field is limited to approximately 70°. There are transitions between monocularity and binocularity. The woodcock's eyes are moved so far back that they perceive the rear half of the visual field no worse than the front. This allows him to monitor what is happening above his head, probing the ground with his beak in search of earthworms.

Hearing.

Like mammals, the bird's hearing organ includes three parts: the outer, middle and inner ear. However, there is no auricle. The “ears” or “horns” of some owls are simply tufts of elongated feathers that have nothing to do with hearing.

In most birds, the outer ear is a short passage. In some species, such as vultures, the head is naked and its opening is clearly visible. However, as a rule, it is covered with special feathers - ear coverts. Owls, which rely mainly on hearing when hunting at night, have very large ear openings, and the feathers covering them form a wide facial disc.

The external auditory canal leads to the eardrum. Its vibrations, caused by sound waves, are transmitted through the middle ear (an air-filled bone chamber) to the inner ear. There, mechanical vibrations are converted into nerve impulses, which are sent along the auditory nerve to the brain. The inner ear also includes three semicircular canals, the receptors of which ensure that the body maintains balance.

Although birds hear sounds over a fairly wide frequency range, they are especially sensitive to acoustic signals from members of their own species. As experiments have shown, various species perceive frequencies from 40 Hz (budgie) to 29,000 Hz (finch), but usually the upper limit of audibility in birds does not exceed 20,000 Hz.

Several species of birds that nest in dark caves avoid hitting obstacles there using echolocation. This ability, also known in bats, is observed, for example, in the Guajaro from Trinidad and northern South America. Flying in absolute darkness, it emits “bursts” of high-pitched sounds and, perceiving their reflection from the walls of the cave, easily navigates it.

Smell and taste.

In general, the sense of smell in birds is very poorly developed. This correlates with the small size of their brain's olfactory lobes and short nasal cavities located between the nostrils and the oral cavity. An exception is the New Zealand kiwi, whose nostrils are located at the end of a long beak and the nasal cavities are elongated as a result. These features allow her to stick her beak into the soil and sniff out earthworms and other underground food. It is also believed that vultures find carrion using not only sight, but also smell.

Taste is poorly developed, because the lining of the oral cavity and the covers of the tongue are mostly horny and there is little space for taste buds on them. However, hummingbirds clearly prefer nectar and other sweet liquids, and most species reject very sour or bitter food. However, these animals swallow food without chewing, i.e. rarely keep it in the mouth long enough to subtly distinguish the taste.

BIRD PROTECTION

Many countries have laws and participate in international agreements to protect migratory birds. For example, US federal legislation, as well as US treaties with Canada and Mexico, provide protection for all such species in North America, with the exception of diurnal raptors and introduced species, and regulate the hunting of migratory game (such as waterfowl and woodcock), as well as certain resident birds, in particular grouse, pheasants and partridges.

However, a more serious threat to birds comes not from hunters, but from completely “peaceful” types of human activity. Skyscrapers, television towers and other tall buildings are deadly obstacles for migratory birds. Birds are hit and crushed by cars. Oil spills in the sea kill many aquatic birds.

With his lifestyle and influence on the environment, modern man has created advantages for species that prefer anthropogenic habitats - gardens, fields, front gardens, parks, etc. This is why North American birds such as the wandering thrush, blue jay, house wren, cardinals, warblers, trupials, and most swallows are now more abundant in the United States than before European settlers arrived. However, many species that require wetlands or mature forests are threatened by the destruction of large amounts of such habitats. Swamps, which many consider suitable only for drainage, are in fact vital for rails, bitterns, marsh wrens and many other birds. If swamps disappear, the same fate befalls their inhabitants. Similarly, deforestation means the complete destruction of certain species of grouse, hawks, woodpeckers, thrushes and warblers, which require large trees and natural forest floor.

Environmental pollution poses an equally serious threat. Natural pollutants are substances that are constantly present in nature, such as phosphates and waste products, but normally remain at a constant (equilibrium) level to which birds and other organisms are adapted. If a person greatly increases the concentration of substances, disturbing the ecological balance, environmental pollution occurs. For example, if sewage water is released into a lake, its rapid decomposition will deplete the supply of oxygen dissolved in the water. The crustaceans, mollusks and fish that need it will disappear, and along with them will disappear loons, grebes, herons and other birds that will be left without food.

Man-made pollutants are chemicals that are virtually absent from the wild, such as industrial fumes, exhaust fumes and most pesticides. Almost no species, including birds, are adapted to them. If a pesticide is sprayed over a swamp to kill mosquitoes or over crops to control crop pests, it will affect not only the target species but also many other organisms. Even worse, some toxic chemicals linger in water or soil for years, enter food chains, and then accumulate in the bodies of large birds of prey that form the top of many of these chains. Although small doses of pesticides will not kill birds directly, their eggs may become infertile or develop abnormally thin shells that break easily during incubation. As a result, the population will soon begin to decline. For example, the bald eagle and brown pelican were in such danger due to the insecticide DDT, consumed along with fish, their main food. Now, thanks to conservation measures, the numbers of these birds are recovering.

It is unlikely that it will be possible to stop the human advance on the world of birds; the only hope is to slow it down. One measure could be stricter liability for the destruction of natural habitats and environmental pollution. Another measure is to increase the area of ​​protected areas in order to preserve natural communities in them, which include species that are in danger of extinction.

CLASSIFICATION OF BIRDS

Birds constitute the class Aves of the phylum Chordata, which includes all vertebrates. The class is divided into orders, and those, in turn, into families. Order names end in “-iformes” and family names end in “-idae”. This list includes all modern orders and families of birds, as well as fossils and relatively recently extinct groups. The number of species is indicated in parentheses.

Archaeopterygiformes: archaeopteryxiformes (fossils)
Hesperornithiformes: hesperornisformes (fossils)
Ichthyornithiformes: Ichthyornisiformes (fossils)
Sphenisciformes: penguin-like
Spheniscidae: penguins (17)
Struthioniformes: ostrich-like
Struthionidae: ostriches (1)
Rheiformes: rheas
Rheidae: rhea (2)
Casuariformes: cassowary
Casuariidae: cassowaries (3)
Dromiceidae: emu (1)
Aepyornitiformes: apiornisiformes (extinct)
Dinornitiformes: Moaformes (extinct)
Apterygiformes: kiwiformes (wingless)
Apterygidae: kiwi, wingless (3)
Tinamiformes: tinamous-like
Tinamidae: tinamu (45)
Gaviiformes: loons
Gaviidae: loons (4)
Podicipediformes: grebes
Podicipedidae: grebes (20)
Procellariiformes: petrels (tube-nosed)
Diomedeidae: albatrosses (14)
Procellariidae: petrels (56)
Hydrobatidae: storm petrels (18)
Pelecanoididae: diving (whale) petrels (5)
Pelecaniformes: pelecaniformes (copepods)
Phaëthontidae: phaetonidae (3)
Pelecanidae: pelicans (6)
Sulidae: gannets (9)
Phalacrocoracidae: cormorants (29)
Anhingidae: darters (2)
Fregatidae: frigatebirds (5)
Ciconiiformes: stork-like (ankle-footed)
Ardeidae: herons (58)
Cochleariidae: shutbills (1)
Balaenicipitidae: shoebills (1)
Scopidae: hammerheads (1)
Ciconiidae: storks (17)
Threskiornithidae: ibis (28)
Phenicopteriformes: flamingo-shaped
Phoenicopteridae: flamingos (6)
Anseriformes: Anseriformes (plate-billed)
Anhimidae: palamedea (3)
Anatidae: Anatidae (145)
Falconiformes: Falconiformes (diurnal predators)
Cathartidae: American vultures or condors (6)
Sagittariidae: secretary birds (1)
Accipitridae: Accipitridae (205)
Pandionidae: Ospreys (1)
Falconidae: falconids (58)
Galliformes: Galliformes
Megapodiidae: megapods, or weed chickens (10)
Cracidae: tree chickens, or gokko (38)
Tetraonidae: grouse (18)
Phasianidae: pheasants or peacocks (165)
Numididae: guinea fowl (7)
Meleagrididae: turkeys (2)
Opisthocomidae: hoatzins (1)
Gruiformes: crane-like
Mesitornithidae: Madagascan rails, or rail partridges (3)
Turnicidae: three-fingered (16)
Gruidae: cranes or true cranes (14)
Aramidae: aramids (1)
Psophiidae: trumpeters (3)
Rallidae: rails (132)
Heliornithidae: cinquepods (3)
Rhynochetidae: kagu (1)
Eurypygidae: sun herons (1)
Cariamidae: cariams, or seriemas (2)
Otididae: Bustards (23)
Diatrymiformes: diatrymiformes (fossils)
Charadriiformes: Charadriiformes
Jacanidae: Jacanidae (70)
Rostratulidae: colored snipe (2)
Haematopodidae: oystercatchers (6)
Charadriidae: plovers (63)
Scolopacidae: snipe (82)
Recurvirostridae: Avocets (7)
Phalaropodidae: phalaropes (3)
Dromadidae: crayfish plovers (1)
Burhinidae: avdotki (9)
Glareolidae: tirkushki (17)
Stercorariidae: skuas (4)
Laridae: gulls or terns (82)
Rynchopidae: cutwaters (3)
Alcidae: auks (22)
Columbiformes: pigeon-shaped
Pteroclidae: sandgrouse (16)
Columbidae: pigeons (289)
Psittaciformes: parrots
Psittacidae: parrots (315)
Cuculiformes: cuckoo-shaped
Musophagidae: banana eaters (22)
Cuculidae: cuckoos (127)
Strigiformes: owls
Tytonidae: barn owls (10)
Strigidae: true (normal) owls (123)
Caprimulgiformes: nightjars
Steatornithidae: guajaro, or fatty ones (1)
Podargidae: Frogmouths or Owljars or Whitelegs (12)
Nyctibiidae: gigantic (forest) nightjars (5)
Aegothelidae: owl nightjars, or owl frogmouths (8)
Caprimulgidae: true nightjars (67)
Apodiformes: swift-shaped
Apodidae: swifts (76)
Hemiprocnidae: tufted swifts (3)
Trochilidae: hummingbirds (319)
Coliiformes: mouse birds
Coliidae: mouse birds (6)
Trogoniformes: trogon-like
Trogonidae: trogons (34)
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A team of biologists has found that the sense of smell is as important to birds as vision or hearing. In addition, scientists were able to find out that sensitivity to odors depends on the habitat of birds: the more important the role of odors in finding food in a given area, the more “subtle” the birds’ sense of smell is. The researchers' work was published in the journal Proceedings of the Royal Society B.

In their work, Silke Steiger, an employee of the Ornithological Center at the Max Planck Institute, and her colleagues compared the representation of olfactory receptor genes in different bird species.

Olfactory receptors located on the sensory neurons of the olfactory epithelium are responsible for the perception of odors. The number of genes for these receptors is thought to correlate with the number of odors that a given organism can distinguish from each other.

In their research, biologists determined the number of olfactory receptor genes in nine species of birds. They found that their number can differ several times from species to species. Thus, the DNA of the southern kiwi contains six times more genes for olfactory receptors than the DNA of the blue tit or canary.

The scientists also tested how many of these genes were functional. In organisms that become less important to the sense of smell for survival, mutations accumulate in the genes of these receptors, which eventually turn them off. Thus, in humans, up to 40 percent of olfactory receptor genes are inactive. As Steiger and colleagues found, in birds, most of the receptor genes are functional, which may indicate the importance of smell for their life.

Scientists found another difference between the bird species studied in their brains: the more olfactory receptor genes a bird carried, the larger the size of its olfactory bulb, the brain structure responsible for processing information about smells.

Scientists have suggested that in birds, like mammals, the number of olfactory genes may depend on their habitat. For example, the southern kiwi, which cannot fly, looks for food on the ground. Kiwis are found only in New Zealand. The northern kiwi (Apteryx mantelli) inhabits the North Island, the common (A. australis), great gray (A. haasti) and rowi (A. rowi) inhabit the South Island, while the small kiwi (A. oweni) is found only on the island Kapiti, from where it is dispersed to some other isolated islands. Due to its secretive lifestyle, it is very difficult to find this bird in the wild.

Biologists believe that for this bird, smell can play the same, if not greater, role than vision. Kiwis mainly rely not on vision - their eyes are very small, only 8 mm in diameter - but on their developed hearing and sense of smell.

Among birds, condors also have a very strong sense of smell. Condors mainly use their excellent vision to search for food. In addition to searching for prey, they also carefully watch other birds nearby - ravens and other American vultures - turkey vulture, greater and lesser yellow-headed catarrh.

Catarths, with the help of their good sense of smell, find carrion, their main prey.

Condors have developed a so-called symbiosis, or mutually beneficial existence, with catarths: catarths have a very subtle sense of smell, capable of smelling the smell of ethyl mercaptan from afar - a gas released at the first stage of decay, however, their small size does not allow them to tear the tough skin of large victims as effectively as is possible Andean condors.

According to scientists, their results prove that the importance of smell in birds has so far been underestimated.

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Which bird has nostrils located at the tip of its nose, due to this it has a highly developed sense of smell?

Kiwi - Apteryx australis - a bird with undeveloped wings, no tail, strong legs with sharp claws. The plumage is soft, feathers evenly cover the entire body. The beak is long and flexible; nostrils at the very tip of the beak. Kiwi is one of the few birds that have a good sense of smell. The kiwi's nostrils are not at the base of the beak, but at the end: at the base of the beak there are “whiskers”, tactile vibrissae, similar to those of a rat. By sticking its long and flexible “nose” into the damp soil, the kiwi sniffs out worms and insects. He also eats berries.

The life of a kiwi goes unnoticed: only at night, in the thick of grasses and bushes, do they go out to hunt, scurrying around fussily, but they do not move far from the bushes and holes under the roots, where they hide during the day. The toes on their strong legs are long, which is why the birds do not get stuck in the damp and swampy soil of the lowlands where they live. During the day, kiwis sleep in burrows under roots located in the bushes. There are also nests lined with grass. The female lays one egg weighing 450 g, which is up to a quarter of the weight of the bird itself. In a week she will lay a second egg. The male kiwi incubates the egg for about 80 days, leaving briefly to feed.

Chicks are born feathered not with down, but, like adults, with hair-like strands of feathers. They spend 5-7 days in the nest and do not eat anything. They store yolk reserves under their skin, which allow them not to starve. Young kiwis grow slowly: they reach maturity only at five to six years. Kiwi wings are tiny, five centimeters, and invisible from the outside. However, from their distant ancestors, kiwis inherited the habit of hiding their beak under their wings when resting.

In general, the sense of smell in birds is very poorly developed. This correlates with the small size of their brain's olfactory lobes and short nasal cavities located between the nostrils and the oral cavity. An exception is the New Zealand kiwi, whose nostrils are located at the end of a long beak and the nasal cavities are elongated as a result. These features allow her to stick her beak into the soil and sniff out earthworms and other underground food. It is also believed that vultures find carrion using not only sight, but also smell.

Taste is poorly developed, because the lining of the oral cavity and the covers of the tongue are mostly horny and there is little space for taste buds on them. However, hummingbirds clearly prefer nectar and other sweet liquids, and most species reject very sour or bitter food. However, these animals swallow food without chewing, i.e. rarely keep it in the mouth long enough to subtly distinguish the taste.

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