Bird class. Birds Body coverings of birds

For a full cycle of life on our planet, the presence of birds of prey in nature is an obvious necessity.

Different species of birds have a natural ability to hunt large prey. Among them: hawks, representatives of eagle and falcon orders, seagulls, owls and others. The unifying criteria for these types are:

• the role occupied in the natural chain;
• way of eating;
• lifestyle (time of day at which the bird begins to hunt).

Birds of prey during the day

According to systematization from the point of view of zoology, the orders of diurnal birds of prey include only falcons, these are falcons themselves, hawks, eagles, buzzards, eagles, and harriers.

It is noteworthy that truly birds of prey have the same threatening and dangerous appearance: their beak is curved like a hook, and their claws are curved and very sharp. The coloration of females and males is almost identical, but females are larger in size.

Common buzzard

Another name is Rough-legged Buzzard. This bird is considered the most famous predator among the tundra forests. She builds her nests throughout the entire Yamalo-Nenets Autonomous Okrug. This predatory species feeds on mice - voles and hamster lemmings. It is characteristic that the numerical component of the buzzards directly depends on the sufficient population of the area with these rodents. Scientists - ornithologists argue that in the conditions of one area, buzzards may be present in abundance, or they may not be present at all.

External signs of the rough-legged buzzard:

• The Buzzard is a large bird in size;
• has wide wings (this visually makes it even larger);
• general color - light, slightly “red”;
• On the belly and under the wings of the predator, black spots are localized, varying in shape (they can form an individual plumage pattern).

Buzzards nest in arboreal areas; they line their nests with grass. If we are talking about the tundra, then in these areas birds are usually located on cliffs and hills. In the case of a good year for mice, the nest of the buzzard can also be found on flat terrain, in swamps, and in the lowlands of rivers.

Buzzards are migratory birds, arriving from warm places in early spring. After the flight, they begin to build their nests. Buzzard Egg Size Larger in size than chicken eggs, rounder in shape, they are spotted and have a white base. The richer the year in prey, the more eggs in the clutch of this bird of prey. The principle of natural selection plays a significant role in the survival of chicks, especially when there is not enough food due to the poor harvest of rodents. Many chicks do not even have the opportunity to live to “flying” age; they are simply eaten by older and stronger chicks.

Buzzards zealously defend their nests. Attacks on people are unlikely; more often birds simply scream loudly or rush at a person. But they fight off arctic foxes or dogs fearlessly, using strong claws. It happens that the Rough-legged Buzzard feeds on dead deer carcasses and their entrails, or rotten fish.

With the arrival of the autumn period, and throughout it, these predators fly to areas of the middle zone.

White tailed eagle

It is one of the largest and largest birds of prey in Russia. His wingspan exceeds two meters, and the bird’s weight sometimes reaches seven kilograms. The owners of a pure white tail are predominantly adult individuals whose age is more than three years, while for others it is dark. Often a young eagle can be mistaken for a golden eagle. However, the golden eagle's tail is slightly rounded, while the white-tailed tail has a sharp wedge shape.

White-tailed eagles nest almost throughout the country; they only avoid the extreme northern areas and dehydrated areas. They make their nests only in the crowns of trees, most often deciduous ones. Very rarely, the “eagle house” is located on steep cliffs.

Whitetails feed on fish and birds swimming in the water. This explains their desire to live near areas rich in water bodies. Their home is located in the same place every year and has a very massive, layered structure up to a meter in height. In open tundra expanses, an eagle's nest is extremely rarely seen; more often it is localized on hills or cliffs.

In early spring, eagles already arrive from the south. The flight is carried out in pairs that differ in consistency. Females lay from one to three eggs in a newly inhabited nest. The eggs are white with spots, similar in size to goose eggs, but slightly smaller. After the first egg is laid, female eagles begin incubation. Chicks hatch from eggs around the first half of June. Their growth is very rapid, plumage occurs quickly.

At the beginning of August, the chicks fly out of the nest, however, they remain under the supervision of their parents for a long time. Whitetails make their way to the southern regions in early autumn.

White-tailed eagles feed on wild birds: geese, ducks, loons; Their diet also consists of hares, large fish species, and rodents. Moreover, these birds of prey are carrion lovers, or hunt animals that are wounded or sick and cannot resist.

White-tailed eagles are rare, valuable birds; they are listed in the Red Book of both our country and the international one. Often the eagle becomes a victim of hunters - poachers, which is very sad for nature and scientists.

Osprey

These birds of prey have a small number, are considered rare, and are listed on the pages of our Red Book.

Species characteristics:

• large size;
• contrasting color: white-yellow underbody; a dark stripe running across the bird's crop; the body, tail and wings are dark on top; there are wide black stripes on the head;
• yellow eye color;
• in conditions of increased anxiety, these birds make peculiar sounds.

The habitat of these predators is the entire world, with the exception of the extreme northern regions. They winter in the African and South Asian tropics.

Ospreys are chosen to provide the necessary living conditions, areas with clean waters rich in fish. They nest on tall trees, with dry tops, away from crowded places. Birds do not betray their nests, returning to them every year. An osprey clutch contains a maximum of four eggs, usually two or three. The eggs are dark in color, with purple spots of various locations.

The chicks live in the nest for about two months without leaving it. They become sexually mature when they reach two years of age.

The peculiarity of the hunting of these birds of prey is that, flying high above the water surface, they hunt down their main food - fish. Having noticed the prey, the osprey dives forward with its paws, and then takes off sharply, catching the prey. This bird disdains carrion, and if hunger begins to wear out, then the predator can hunt ducks or mice.

The osprey goes to winter from September to October.

The number of this species is inexorably declining, this is due to the direct extermination of predators, unfavorable ecology, and deforestation. All this makes it impossible for birds to nest safely.

Goshawk (hawk)

The size of the bird is larger than that of a crow, weighing up to one and a half kilograms.

Character traits:

• clear stripes running across the underside of the bird's body;
• dark gray upper body;
• eyes are very bright yellow;
• young goshawks are colored red or brown.

Birds of this species were persecuted for a very long time due to the fact that they were considered predators that caused particular harm. As a result, their numbers have fallen, and now they are protected by law.

Goshawks feed on medium-sized fish and small animals such as hares, squirrels, etc. They hunt for dying animals that are doomed and weakened due to illness or injury. Thanks to this, predators are considered forest orderlies.

Goshawk distribution zone - north of the forest-tundra. They winter either where they nest, or fly away to where it is warmer.

Harrier

It is a bird that lives, more often, in open spaces - forest-tundra zones, forest-steppe and taiga zones. The main living condition is the abundance of small rodents.

The harrier is about the size of a crow, but has a longer tail and a graceful body. The colors of the male and female are different.

Features of the color of the male:

1. white body with an ashy coating on top;
2. There are black streaks at the ends of the wings.

Female color:

1. body red and gray;
2. The lumbar region is white.

Harriers build their nests on the surface of the ground. The clutch contains from three to five white, slightly spotted eggs. They are smaller than chicken eggs and the most round.

The harrier is a migratory bird. Hunts by flying not very high above the ground.

Peregrine Falcon

The most famous falcon. This is a rare and valuable bird breed. Unfortunately, poachers especially love to catch these very predators, as a result of which their fate is extremely sad. Peregrine falcons have been practically exterminated and are very rare even in uninhabited areas.

In the United States, in order to restore the numbers of these birds, they kept in specialized enclosures. Peregrine falcon chicks are raised and then released into the wild. However, even taking into account the usefulness and importance of these events, it should be said that they are very expensive in material terms. Falcons released into the wild have great monetary value.

The peculiarity and pride of the peregrine falcon are its clear, piercing black eyes, above which black brow ridges emerge. It is not for nothing that in Rus' heroes were often called “clear falcons.”

Within the Yamal territory, the falcon population is no more than two hundred pairs of these birds of prey. The part of Russia most populated by falcons is the Western Siberian tundra, where the situation with predators is quite stable.

External characteristics of the peregrine falcon:

The falcon is rightfully considered one of the fastest living creatures on the planet, and among birds it has no equal. He hunts by attacking his prey from above, in a steep dive. Small sized birds, peregrine falcon grabs with strong paws, and knocks down larger ones at speed with sharp claws on their hind toes. Then the predatory falcon, in flight, grabs the falling prey.

Peregrine falcons often bring their prey from places far from the nest. Previously, there was an opinion that they do not hunt near their nests, however, observations have shown the opposite. It is not uncommon for a falcon to hunt near a nesting female.

Predators of this species very zealously and aggressively defend their nest. Noticing the danger, the peregrine falcon raises a frantic cry and, diving, attacks the uninvited guest. A little later, the female joins the male. Falcons also attack people, but with the goal of simply scaring them without touching them.

The peregrine falcon is a sophisticated hunter. Among its victims are entire collections of the rarest birds, the existence of which even ornithologists do not always know.

Falcons nest, choosing a variety of places for this. It can be rocks, strangers, abandoned nests, even hollow trees or just plain land. An important condition for nesting is the possibility of a good overview of the area. The number of clutches is from three to five eggs. Similar in size to chicken.

What is typical is that grown chicks do not eat small falcons, unlike rough-legged buzzards. This is considered a noble trait of this bird species. However, it is worth rightly noting that their numbers are absolutely independent of the harvest of rodents, which means that the peregrine falcon and its chicks will definitely not die from hunger.

Falcons are migratory, not flocking birds leading a solitary lifestyle. One pair of peregrine falcons builds a nest far from the other. The pairs are permanent and stable. However, their nests are always in the same place. Predators arrive at the beginning of spring and fly away at about the same time as other birds.

Merlin

It is considered the smallest falcon. The nesting territory of this predator is extensive, but merlins avoid areas that are too northern. This type of predator is quite rare.

The food type of merlins is small birds caught and captured in flight. They make nests mainly in trees, in abandoned crow's nests. The number of eggs hatched is up to five. Both females and males act as brood hens, but the former participate to a greater extent.

It is noteworthy that the merlin is only the size of a pigeon. But at the same time it is a worthy predator in the tundra and its forests. This bird is protected by law.

Owls are nocturnal predators. These are birds known to everyone, which have been repeatedly mentioned in children's fairy tales.

Features of the appearance of an owl:

Owls exterminate various rodents, while bringing great benefits to people. Therefore, they are protected by law from poachers and simply those who like to make fun of living beings.

Snowy owl (or snowy owl)

A very colorful nocturnal predator that lives in the steppes and tundra forests. Hunts voles, partridges, hamsters - lemmings. Sometimes they catch hares and even arctic foxes and stoats.

The small peoples of the north often consumed owl meat for food, and for this purpose they hunted it.

Short-eared owl

It is smaller in size than the polar one. It also feeds on rodents and lives in tundra areas. There have been cases when a short-eared owl was seen over the sea.

There are also other types of owls, for example: Lapland, hawk, eagle owl.

It is noteworthy that the hawk owl is a diurnal predator, even somewhat similar to a falcon.

Eagle owls are the largest birds from the owl order. They have ears on their heads and are motley and red in color. An eagle owl can attack a buzzard or a hawk, but its diet mainly consists of rodents and small animals.

In northern conditions, the eagle owl can hunt during the day.

Birds are warm-blooded vertebrate, oviparous animals adapted for flight.

More than 10,000 species are known in the world, varying in size, shape and lifestyle, living in almost all corners of the globe.

Are birds animals or not?

Birds belong to the animal kingdom, like other living organisms, with the exception of plants, fungi and bacteria. However, in everyday life it is customary to call only mammals animals, which often leads to confusion as to whether the animal is a fish, a frog or a reptile.

Basic characteristics of birds

These animals have several distinctive features. During the process of evolution, their forelimbs turned into wings, thanks to which almost all species are adapted for flight.

Their skin is dry, without sweat glands, and completely covered with feathers, which play an important role in flight. Another characteristic feature is their beak, which replaces jaws.

Classification of birds

The class of birds is divided into almost 30 orders, which in turn are divided into families, genera and species. It should also be taken into account that there is still no clear classification, therefore different families and orders are often classified as different groups.

Archeopteryx

Here is one of the classifications, including some extinct species.

The whole class is divided into two subclasses:

• lizardtails (extinct Archeopteryx);
• fantails (all others).

Fantails are divided into four superorders:

• toothed (also extinct);
• floating;
• ratites;
• ancient palatal and new palatal.

The swimmers consist of one group - penguins.

Ratites or drenopalatines are flightless species and include ostriches, cassowaries, kiwis and tinamous, in a total of five orders.

New palates are the largest group, including more than twenty orders. Orders usually consist of one to three families, less often - five or six, and the largest order - passerines, includes 66 families and more than 5000 species, that is, more than half of all known.

It is worth noting: as already mentioned, avian classifications may vary, for example, according to another classification, penguins are considered a superorder of neopalates, but tinamous are not classified as ratites.

Features of structure and life activity

Being descendants of reptiles, birds have retained some of their features. They have no sweat glands, dry skin, and their legs are covered with scales.

Like reptiles, they are not viviparous and lay eggs.

At the same time, the ability to fly was also reflected in the structure of their body. Their muscles are stronger and their overall muscle mass is higher relative to their body than that of reptiles.

To stay in the air, their body is relatively small and weighs little due to light bones, and their small head reduces air resistance during flight.

On the contrary, those of them that live on the ground can reach enormous sizes and are heavy.

During flight, birds spend a lot of energy, hence the need for large amounts of food and a high metabolic rate. For this reason, their digestion processes have accelerated, and their body temperature is also high.

As for the diet itself, among them there are both herbivores, carnivores and omnivores.

In addition, we can note individual characteristics that have appeared in different species, depending on their habitat and lifestyle. In flightless ones, the wings have practically disappeared, but the legs, on the contrary, are powerful and strong, and their size and weight are much higher than those of flying ones.

The beak of predators is pointed and curved, convenient for tearing meat; in those that feed on solid food, it is powerful and thick.

The paws of predators are equipped with claws, those of swimmers have a membrane formed between their toes, and those of trees have long curved claws for clinging to the surface.

What science studies birds

The science that studies birds is called ornithology (from the Greek ὄρνιθος (bird) and λόγος - study). The term was introduced by the Italian scientist U. Aldrovandi in the 16th century.

Ornithologists study the origin, habits, structure of birds and much more, and also engage in systematization and description. Until the 19th century, scientists were only engaged in describing animals, studying their structure and way of life, and later they also began to study their distribution around the globe and migration.

Ornithologists' research plays an important role in other fields of science, such as breeding and genetics, and helps in agriculture and forestry.

External and internal structure of birds

As mentioned above, on the one hand, the structure of the bird’s body has much in common with reptiles, on the other, many of their body parts and organs are very different in structure from both reptiles and other animals.

Bird skeleton

The diagram of the pigeon skeleton is shown in the picture.

The structure of a bird's skeleton is directly related to their ability to fly. Bird bones are light and often hollow. The parts of the spine are often fused to each other, except for the cervical, which, on the contrary, is flexible.

The sternum forms a strongly prominent keel, to which strong wing muscles are attached. In flightless animals, it is, accordingly, absent.

Digestive system

The food eaten goes from the pharynx to the esophagus, from there to the stomach and then to the intestines. Since representatives do not have teeth, the stomach is used to grind food, which the birds fill with small pebbles, and then its powerful muscular walls grind the food.

The bird's intestines are very short so as not to create excess weight, and since the rectum is poorly developed, feces do not accumulate in the body and are quickly eliminated.

A well-known feature of avian digestion is its high speed. In some species, complete digestion of food takes a matter of minutes.

Respiratory system

The structure of the respiratory system of birds is also largely related to their ability to fly, as well as the increased gas exchange that their body needs. The respiratory system of birds has a complex structure compared to those of other animals.

Its characteristic features are small, dense lungs. In addition, special air sacs are associated with the lungs, which are necessary for normal breathing during flights.

When a bird inhales air during flight, it enters the air sacs, and when exhaled, thanks to the special structure of the lungs, it passes through them again.

Circulatory system

The avian circulatory system is closed and has two circles.

The bird's heart has four chambers and its heart rate is very high, especially during flights. The lymphatic system is poorly developed.

Excretory system

The excretory organs of birds are similar to those of reptiles. Their kidneys are very large due to increased metabolism.

A ureter emerges from each kidney and opens into the middle section of the cloaca. The adrenal glands are located near the upper edge of the kidneys. There is no bladder, as in the case of the rectum, this allows urine not to linger in the body and lightens the weight.

Brain

Birds have a well-developed nervous system compared to reptiles, and the brain is much larger. In flying birds it is much larger in relation to the rest of the body than in non-flying birds.

The size of brain regions is directly related to the lifestyle of animals. For example, their medulla oblongata and cerebellum are well developed, since they are responsible for those processes that occur especially actively in them.

On the contrary, the olfactory lobes are small, and therefore most of them have difficulty distinguishing odors (with the exception of scavengers). The intelligence of many species is quite high, they can use improvised objects, and are capable of learning.

Reproduction

Birds have pronounced sexual dimorphism (females and males are very different from each other). Most species are monogamous and form stable pairs, some for several seasons, others for life.

Birds are not viviparous and reproduce by laying eggs. For the development and subsequent hatching of the chick, high temperatures are required, so one of the parents (or both in turn) hatches it.

Parents actively care for their offspring: they bring food for their children, warm them, protect them from enemies and teach them to fly. In different polygamous species, both the female (chicken) and the male (ostrich) can take care of the chicks.

Fertilization

Fertilization in birds is internal, just like in other vertebrates. A peculiarity of the avian reproductive system is the absence of special openings in the female and external genitalia in the males (with the exception of some species).

During mating, the male simply presses his cloaca against the female (this is where the reproductive tract exits) and injects seed into her. Subsequently, it enters the ovaries and fertilizes already mature eggs there.

Conclusion

Birds play a huge role in the life of the ecosystem. Carnivores and insectivores help regulate the numbers of other animals, while at the same time, many birds themselves feed on other vertebrates. Also, those birds who feed on plant fruits contribute to the spread of their seeds.

Birds also play a huge role in people’s lives, from food, housekeeping to culture and art. A number of birds occupy an important place in heraldry; their images adorn the coats of arms of countries and cities. Finally, many of them are simply pleasing to the eye and ear.

Unfortunately, we cannot fail to mention the harm that people cause to birds. It is difficult to say how many species of birds have been destroyed by humans, not counting the hundreds more that are on the verge of extinction. Only relatively recently have endangered species come under protection, and even attempts are being made to bring back to life those that have already disappeared.

It includes a number of extinct species, as well as 5 living orders, including:

Order Cassowaries (Cassowaries and Emu)

Cassowaries and emus from the order of cassowaries, or Australian ostriches ( Casuariformes), are large, flightless birds, with long necks and legs. They have long feathers that resemble coarse fur, but the head and neck are almost hairless.

There are four extant species of cassowaries:

• Helmeted cassowary ( Casuarius casuarius);
• Orange-necked cassowary ( C. unappendiculatus);
• Cassowary-muruk ( C. bennetti);
• Emu ( Dromaius novaehollandiae).

Order Kiwiformes (Kiwi)

Experts do not agree on the exact number of species belonging to the order Kiwiformes ( Apterygiformes), but there are at least three: the southern kiwi, the great gray kiwi and the small gray kiwi. According to the latest data, scientists have identified two more species: the northern brown kiwi and Apteryx rowi.

Birds from this order are endemic to New Zealand. Kiwis are flightless birds with tiny, almost vestigial wings. They are strictly birds, digging out larvae and earthworms at night using their long, narrow beaks.

New Zealand's national bird, the kiwi, is vulnerable to diseases including dogs, which were introduced to these islands hundreds of years ago by European settlers.

Order Rheaformes (Nandu)

There are only two species of rhea in the order Rheaidae ( Rheiformes), both of which live in the , and steppes of South America. These flightless birds have long feathers and three toes on each foot; they also have claws on each wing, which are used during defense.

Rheas are similar to ostriches in appearance, however, the extent of their relationship remains controversial among scientists. The body size of rheas is almost half the size of ostriches.

Order Ostriformes (Ostriches)

The only surviving representative of the order Ostrichidae ( Struthioniformes) - African ostrich ( Struthio camelus), who is considered a real record holder. Not only is it the tallest and heaviest living bird, but the ostrich can also reach speeds of up to 70 km/h, and can also run long distances at speeds of up to 50 km/h. Ostriches have the largest eyes of any vertebrate, and their eggs, weighing up to 2 kg, are the largest of any living bird.

Subclass New palatines

New palatines (Neognathae) birds have a much longer history that reaches the Mesozoic era and this subclass includes 25 orders, such as:

Order Aciformes, or Ankleidae (Storks, herons, ibises, etc.)

The order of birds is stork-like, or wavy-footed ( Ciconiiformes) includes herons, storks, ibises and others, more than 100 species in total. All of these birds are long-legged, sharp-billed carnivores that live in wetlands. Their long, flexible toes are unwebbed, allowing them to stand in thick mud without drowning. Most are solitary hunters, slowly stalking their prey before quickly striking with their powerful beaks; they feed on fish, amphibians and insects.

The earliest known ancestors of today's herons, storks and their relatives date back to the Late Era, about 40 million years ago. The closest living relatives are flamingos.

Order Shearwaters (Albatrosses and petrels)

Albatross

Birds in the order Petrel-like ( Procellariiformes), also known as tubenoses, include more than 125 living species, placed into four extant families:

• Petrels ( Procellariidae);
• Albatross ( Diomedeidae);
• Stormbreeds ( Hydrobatidae);
• Diving petrels ( Procellariidae).

These birds spend most of their time at sea, flying over the water and diving into it to catch fish and other small ones. Tubebills are colonial birds that return to land only to breed (breeding sites vary by species, but in general these birds prefer remote islands and rugged coastal cliffs), they are monogamous and form long-term bonds between mating pairs.

The largest species of the order are wandering albatrosses, whose wingspan reaches 3.25 m. The smallest species is Halocyptena microsoma- has a wingspan of less than 30 cm.

Order Passeriformes (Sparrows, starlings, crows, etc.)

Order passeriformes ( Passeriformes), are the most diverse group of birds, consisting of more than 5,000 species, including: sparrows, finches, thrushes, starlings, crows, swallows, larks and many others. These birds have a unique leg structure that allows them to tightly grasp thin twigs, reeds and fragile grass stems; some species can even cling to vertical surfaces, including mountain slopes and tree trunks.

In addition to their unique leg structure, passerines are distinguished by their complex vocalizations. Although these are not the only birds capable of making sounds using the syrinx, this organ is the most developed in passerines. Each member of the squad has unique sounds, some of them simple, others long and complex. Some species learn vocalizations from their parents, while others are born with the innate ability to sing.

Order Loons (Loons)

Order of birds ( Gaviiformes) includes five living species of loons: the red-throated loon, the black-throated loon,
the white-necked loon, the black-billed loon and the white-billed loon. Loons are freshwater waterfowl common in the northern parts and Eurasia. The legs located behind their bodies provide the bird with strength in the water, but make these birds clumsy on land. Gaviiformes They have fully webbed feet, elongated bodies, and dagger-shaped beaks well suited for capturing fish and other aquatic invertebrates.

These birds go to land to nest and build their nests close to water. Both parents care for the chicks, who sit on the adults' backs for protection until they are ready to live independently.

Order Pigeonidae (Pigeons and turtle doves)

Order Pigeonidae ( Columbiformes) includes more than 300 species of pigeons, including rock pigeons, pigeons, turtle doves, ringed doves, crowned pigeons, etc. Pigeons are small to medium-sized birds characterized by short legs, purple coloring, short necks and small heads. Pigeons have short beaks that are hard at the tip but softer at the base.

These birds are common in meadows, fields, deserts, farmlands and cities. They also, to a lesser extent, inhabit and, as well as.

Order Anseriformes (Ducks, geese, swans, etc.)

Bird order Anseriformes ( Anseriformes) includes ducks, geese, swans, etc., which tend to be somewhat irritable due to loud calls. There are about 150 living species in this order. Most prefer freshwater habitats such as lakes, streams and ponds, but some live in marine regions, at least during the breeding season.

All Anseriformes are equipped with webbed feet, which allow them to move more easily through the water. However, you may be surprised to learn that most of these birds are exclusively herbivores; only a few species feed on insects, molluscs, plankton, fish and crustaceans. Anseriformes often find themselves on the downside, not only because of the people who love their meat, but also because of coyotes, foxes, raccoons and even striped skunks.

Order Woodpeckers (Woodpeckers, toucans, etc.)

In the order of woodpeckers ( Piciformes) includes woodpeckers, toucans, puffbirds, nonnulas, nuns, brachygalbas, jacamaras, honeyguides, etc., about 400 species in total. These birds love to nest in trees; and the most famous birds of the order Piciformes- woodpeckers - tirelessly gouge holes in tree trunks with their beaks. Some species are antisocial, showing aggression towards other species or even their own birds, while others live well in large groups.

Thanks to the structure of their paws, oti easily climb tree trunks. For many Piciformes they also have strong legs and stout tails, as well as thick skulls that protect their brains from the effects of wood gouging. Beak shapes vary widely among members of this order.

Woodpeckers and their related species are found in most parts of the world, with the exception of Madagascar and Madagascar.

Order Crane-like (Cranes, coots, rails, etc.)

Red-crowned crane

Order Craniformes ( Gruiformes) includes about 200 living species. Members of the order vary widely in size and appearance, but are generally characterized by their short tails, long necks and rounded wings.

Cranes with long legs and necks are the largest members squad; The Indian crane is more than 1.7 m high and has a wingspan of up to 2.5 m.

AND Uraliformes also include birds that do not fit into other orders in their characteristics. Currently, the detachment includes 9 living families.

Order Nightjars

In the order Nightjars ( Caprimulgiformes) there are about 100 species of birds distributed throughout the world, with the exception of Antarctica. Their patterned feathers are often quite variegated, so they fit well into their preferred feathers (these birds tend to nest either on the ground or in trees).

In the modern classification, the nightjar order includes 5 families:

• Guajaro ( Steatornithidae);
• Frogmouths ( Podargidae);
• Gigantic nightjars ( Nyctibiidae);
• Owl Nightjars ( Aegothelidae);
• True nightjars ( Caprimulgidae).

Order Cuculiformes (Cuckoos)

Common cuckoo

Order Cuckoo-shaped ( Cuculiformes) includes the only family of cuckoos, which has about 140 species.

Cuckoos are medium-sized, thin-skinned birds that live in savannahs and feed primarily on insects and insect larvae. Some species of cuckoo are known to plant their eggs in other people's nests, and when a cuckoo chick hatches, it will sometimes push other chicks out of the nest!

Order Galliformes (Guinea fowl, pheasants, partridges and crucians)

Common pheasant

Some representatives of Galliformes ( Galliformes) are well known to people who love to eat bird meat, including pheasants, quail, turkeys, guinea fowl and others. In total, this order includes 5 families and about 250 species. Many of the less familiar birds are subject to intense hunting pressure and are now facing extinction. Other members of the order, such as chickens, quails and turkeys, have been fully domesticated and are often raised in huge quantities on farms around the world.

The smallest galliform species is the painted quail, which has a body length of less than 15 cm; the largest species of the order is the North American wild turkey, which can reach a length of more than 1 m and a weight of about 8 kg.

Order Pelicanidae (Pelicans, herons and ibises)

To the order pelican-like ( Pelecaniformes) include the families: pelicans, herons, shoebills, hammerheads and ibis. These birds are characterized by their webbed feet and their various anatomical adaptations for catching fish, their main food source; many species are excellent divers and swimmers.

Pelicans, the most famous members of the order, have special leather pouches at the bottom of their beaks that allow the birds to effectively catch and hold fish. There are eight species of pelicans in total.

Order Penguinaceae (Pigguins)

Order penguin-like ( Sphenisciformes) includes six genera and about 20 species of penguins. The most diverse are the crested penguins, a genus that includes 6 species.

Parrots are monogamous, forming strong pairs. Most parrots feed almost exclusively on fruits, seeds, nuts, flowers and nectar, but some species may eat (such as invertebrate larvae) or small animals (such as snails).

Mouse Bird Squad

Bird Squad Coliiformes includes six living species of mousebirds that deftly climb trees in search of fruits, berries and the occasional insect. These birds are restricted to the open forests, scrub and savannas of sub-Saharan Africa. They usually gather in flocks of up to thirty individuals, except during the breeding season.

One interesting fact about mousebirds is that they were much more numerous in late times than they are today; in fact, some naturalists refer to these virtually unknown birds as "living fossils."

Order Coraciiformes (Kingfishers, bee-eaters, rakshas, ​​etc.)

Coraciiformes ( Coraciiformes) is an order of mainly carnivorous birds, which includes kingfishers, bee-eaters, ground rakshas, ​​rollers, broadmouths, etc. Some members of this order are solitary, while others form large groups. Many species are brightly colored, and all have feet with three toes pointing forward and one toe pointing backward. Coraciiformes They like to nest in holes in trees or dig tunnels in the mud along river banks.

According to modern classification, the order Coraciiformes is divided into 6 families:

• Kingfishers ( Alcedinidae);
• Earth rakshas ( Brachypteraciidae);
• Roller or true raksha ( Coraciidae);
• Shchurkov ( Meropidae);
• Momotovs ( Momotidae);
• Todievs ( Todidae).

Order Charadriiformes

Order Charadriiformes ( Charadriiformes) has about 350 species of birds found along coastlines. Charadriiformes are skilled fliers; some species undertake the longest and most spectacular migrations in the class of birds.

Charadriiformes eat a wide variety of foods, including marine worms, crustaceans and earthworms, but surprisingly, they almost never eat fish!

Order Fritillary (Hooved and Grouse)

Representatives of the order Fritillaria ( Pteroclidiformes) are medium-sized birds native to Africa, Madagascar, the Middle East, Central Asia, India and the Iberian Peninsula. There are 16 species of fritillaries, which belong to two genera.

Sandgrouse are characterized by their small heads, short necks, short, feathered legs, and ragged bodies; Their tails and wings are long and sharp, good for taking off quickly to escape predators.

Order Owls (Owls, owls, eagle owls, barn owls, etc.)

Order Owls ( Strigiformes) consists of more than 200 species, medium to large birds equipped with strong claws, good hearing, and keen eyesight. Because they hunt at night, owls have especially large eyes (which help them see in the dark) as well as binocular vision, which helps them see prey better.

They are opportunistic carnivores, feeding on everything from small mammals, reptiles and insects to other birds. Having no teeth, they swallow their prey whole and after about six hours regurgitate the indigestible parts of the eaten prey.

Owls live on every continent except Antarctica. They are found in a wide variety of terrestrial habitats, ranging from dense forests to wide-open grasslands.

Order Falconiformes (Birds of Prey)

Black vulture

Falconiformes ( Falconiformes), or birds of prey, include eagles, hawks, kites, secretary birds, ospreys, falcons, vultures and vultures, about 300 species in total. Representatives of the order are formidable predators, with powerful claws, twisted beaks, keen vision and wide wings, well suited for flight and diving. Falconiformes hunt during the day, feeding on fish, small mammals, reptiles, other birds and abandoned carrion.

The largest bird of prey is the Andean condor, whose wingspan approaches 3 m. One of the smallest birds of prey is the steppe kestrel, with a wingspan of less than 75 cm.

Order Swifts (Hummingbirds and Swifts)

Order of swift-shaped, or long-winged ( Apodiformes) is the most numerous in the class of birds after passerines, it has about 450 species of swifts and hummingbirds. In the Sibley-Ahlquist classification, this order rises to a superorder Apodimorphae, in which hummingbirds are separated into a separate order Trochiliformes.

Birds are characterized by their small size, short legs and tiny feet. Hummingbirds and swifts included in this group also have numerous adaptations for specialized flight.

Hummingbirds are common in different areas of North, Central and South America, and swifts can be found on all continents of the world, with the exception of Antarctica. Earliest known members Apodiformes were fast birds that evolved during the early Eocene era in northern Europe about 55 million years ago; Hummingbirds appeared a little later, they separated from the early swifts after the late Eocene.

Order Trogoniformes (Trogon and Quezal)

In the order trogon-like ( Trogoniformes) there are about 40 species of trogons and quesals, tropical forest birds found in the Americas, southern Asia, and sub-Saharan Africa. These birds are characterized by short beaks, rounded wings and long tails, and many are brightly colored. They feed mainly on insects and fruits, and also build their nests in trees or abandoned insect burrows.

Mysterious as their vaguely alien names, trogans and quesals have proven difficult to classify: in the past, scientists have grouped these birds with all orders, from owls and parrots to tinamoiformes. However, recent molecular evidence indicates that trogons are closely related to the Coraciiformes, with which they may have diverged as early as 50 million years ago. These birds are rarely found in the wild and are considered particularly valuable finds by ornithologists.

Order Turaciformes (Turacos and banana eaters)

Turaciformes ( Musophagidae) - a detachment of birds that were previously classified as cuckoo-like birds. Recent genetic analysis has confirmed that it is a separate order.

Musophagidae are medium-sized birds endemic to sub-Saharan Africa, where they live in forests and savannah. They fly poorly, but move quickly through trees. They feed mainly on fruits and to a lesser extent on leaves, buds and flowers, and occasionally eat small insects, snails, and slugs.

These are gregarious birds that do not migrate, but gather in family groups of up to 10 individuals. Many species can produce high-pitched alarm calls that alert other animals to the presence of predators or humans.

Order Flamingiformes (Flamingos)

Flamingoformes ( Phenicopteriformes) is an ancient order of birds consisting of six species from the genus flamingo. These birds use their special beaks to retrieve tiny plants and animals from the water. Flamingos are very social birds, forming large colonies of several thousand individuals. They synchronize mating and egg laying for the dry season, and when water levels drop, flamingos build their nests in the exposed mud. Their preferred habitats include lagoons, mangrove swamps, large alkaline or saline lakes, etc.

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 discovery in Europe of the remains of an extinct creature, Archeopteryx, made it possible to connect birds with reptiles. (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.

EXAMPLE OF MARRIAGE DEMONSTRATION. The male magnificent lyrebird living in Australia, courting a female, unfolds his huge tail and bends it forward over his head, almost completely “curtaining” it with feathers.

Birds are the youngest in evolutionary terms, highly developed animals, which are characterized by walking on two legs, feather cover, wings and beak, warm-bloodedness with an intense metabolism, a well-developed brain and complex behavior. All these features of birds allowed them to spread widely across the globe and occupy all habitats - land, water, air; they inhabit any territory from high polar latitudes to the smallest oceanic islands.

The habitat was a selection factor in the evolution of birds (body structure, wings, limbs, methods of movement, food production, features of breeding).

Birds are characterized by seasonal cycles, which are most noticeable in migratory birds and less pronounced in migratory or sedentary birds. The greatest species diversity of birds is concentrated in the tropical zone. Almost every bird species can live in several different biogeocenoses.

The most numerous group of forest birds includes carnivores, herbivores and omnivores. They nest in hollows, on branches, on the ground. Birds of open places - meadows, steppes, deserts - build nests on the ground; Coastal birds nest on rocks, forming bird colonies, where several species of birds not only live together, but also protect themselves from enemies.

Birds are characterized by clearly defined dynamics of population changes. Thus, the maximum of birds on Earth (up to 100 billion individuals) is observed after the emergence of the young, the minimum - by the beginning of next summer (decrease in number up to 10 times). Human economic activity plays a major role in changing the number of birds. The areas of forests, swamps, meadows, and natural reservoirs are being reduced, and some birds are simply exterminated.

The role of birds in food chains is great, since they represent the final links of many food chains.

Birds are of great importance in the distribution of fruits and seeds. In human economic activity, the importance of birds is mainly positive: they exterminate rodents, insect pests, and weed seeds, which can be considered as biological protection of fields and gardens. Birds must be protected and protected, fed, especially in winter, and their nests must not be destroyed. Without birds - so bright, mobile, loud-voiced - our forests, parks, meadows, and reservoirs become joyless and dead.

The damage caused by birds is incomparably lower than their benefit. They devastate orchards and vineyards, peck out sown seeds, pull out seedlings, so they have to be scared away. Cases of bird collisions with airplanes have become more frequent. Birds carry infectious diseases - influenza, encephalitis, salmonellosis, and spread ticks and fleas.

A person is engaged in poultry farming, raising poultry, as well as ornamental and songbirds.

80 species of birds are listed in the Red Book of the USSR.

There are about 8,600 species of birds in the world fauna, of which approximately 750 species are found within the territory of our country. Birds are common on all continents of the globe with the exception of the interior regions of Antarctica; some of them spend most of their lives on the open sea. On land, different species of birds are found everywhere where there is plant or animal food for them - in forests, bushes, parks, shelterbelts, meadows, swamps, deserts, mountains and tundra.

Class characteristics

Birds are very similar in structure to reptiles and represent their progressive branch, the evolution of which followed the path of adaptation to flight. Birds are often combined with reptiles into the group of lizards (Sauropsida). Birds are bipedal amniotes whose forelimbs have developed into wings; the body is covered with feathers, the body temperature is constant and high.

The organization of birds is adapted to flight conditions. The body is compact, the skeleton is extremely lightweight. The spread wings and tail form an area much larger compared to the area of ​​the body. In the body structure of birds, one can note not only features characteristic of birds, but also features common to reptiles. Thus, there are no glands in the skin of birds, with the exception of the coccygeal gland above the root of the tail. Some birds also lack this gland.

Coverings of the body. The skin is very thin. There are horny sheaths on the beak, horny scales on the limbs, and claws on the fingers. Derivatives of the skin are feathers, phylogenetically related to scaly formations (this is indicated by the similarity in the development of feathers and scales in the early stages). Feathers cover the outside of a bird's body, help retain heat (thermal insulation function), provide streamlining of the body, protect it from damage, and form load-bearing planes in flight (wings, tail).

There are contour and down feathers.

Outline feathers consist of a strong and elastic hollow horny trunk (rod) and a soft fan. The fan is formed by a dense network of thin horny plates - barbs. The first-order barbules extend parallel to one another from the rod, on both sides of which numerous thinner second-order barbs extend, the latter interlocking with small hooks. There are long and especially strong feathers - flight feathers - they form the plane of the wing; long and strong tail feathers form the plane of the tail, the remaining integumentary contour feathers provide a streamlined body shape. 9-10 primary flight feathers are attached to the rear edge of the skeleton of the hand; during flight they form a thrust that carries the bird forward, and to a lesser extent - a lifting force. The secondary flight feathers are attached to the forearm and form the main load-bearing surface of the wing. On the leading edge of the latter there is a small wing with several short feathers that make it easier for the bird to land. Tail feathers take part in flight control and braking.

Down feathers have a thin short shaft and a soft fan with thinner and fluffy beards, without hooks (i.e. not connected to each other). Down feathers increase thermal insulation and help reduce heat transfer.

Birds molt periodically (once or twice a year), and new feathers grow in place of old feathers.

Skeleton. The bones of the skeleton are filled with air (pneumatic) and are lightweight. The thickness of the bones is small, the tubular bones are hollow inside, except for air, they are partially filled with bone marrow. Many bones fuse together. Thanks to these features, the bird's skeleton is light and strong. The spine is divided into five sections: cervical, thoracic, lumbar, sacral and caudal. The cervical vertebrae (there are from 11 to 25) are movably connected to each other. The vertebrae of other sections are fused to each other and are motionless, which is necessary during flight. The thoracic vertebrae are almost motionless; the ribs are attached to them. The ribs have hook-shaped processes that overlap the adjacent posterior ribs. The thoracic vertebrae, ribs, and broad breastbone, or sternum, form the rib cage. The sternum has a high ridge at the bottom - the keel. Powerful muscles that move the wing are attached to it and the sternum.

All lumbar and sacral (there are two) vertebrae are fused with each other and with the iliac bones; several caudal vertebrae join them, forming the complex sacrum characteristic of birds. It serves as a support for a pair of hind limbs, which bear the entire weight of the body. There are 5-9 free caudal vertebrae, the terminal caudal vertebrae are fused into the coccygeal bone, to which the tail feathers are attached.

The forelimb girdle consists of three paired bones: coracoids, scapulae and clavicles. The skeleton of the forelimb, which turned into a wing, is significantly modified. The wing skeleton consists of one humerus, two forearm bones (ulna and radius), several hand bones (most of them fused to form one bone) and three fingers. The skeleton of the fingers is sharply reduced.

When moving on land, the entire weight of the body is transferred to the pelvic girdle and hind limbs, and therefore they are also transformed. The hind limb girdle consists of three pairs of bones that fuse to form the pelvis. Along the midline of the body, the pelvic bones do not fuse together; this is the so-called open pelvis, which allows birds to lay large eggs. The skeleton of the hind limb is formed by long and strong tubular bones. The total length of the leg exceeds the length of the body. The skeleton of the hind limb consists of one femur, fused bones of the lower leg and foot bones that form the tarsus, and four toes.

The skull is characterized by complete fusion of all bones until the sutures disappear, extreme lightness and large eye sockets close to each other. The jaws of birds are represented by a light beak, devoid of teeth.

Musculature well developed, its relative mass is greater than that of reptiles. At the same time, the abdominal muscles are weaker than the pectoral muscles, which make up 10-25% of the total mass of the bird, i.e. approximately the same as all other muscles combined. This is due to the fact that the paired pectoralis major and minor muscles, starting on the sternum and its keel, lower and raise the wings during flight. In addition to the pectoral muscles, the complex work of the wing in flight is controlled by several dozen small muscles attached to the body and forelimbs. The muscles of the neck and legs are very complex. Many birds have a special device on the tendon of the deep toe flexor muscle that automatically secures the toes in a compressed state when the bird wraps them around a branch. Therefore, birds can sleep sitting on branches.

Digestive system. The digestive organs are characterized by the complete absence of teeth in modern birds, which greatly facilitates the body for flight. In granivorous birds they are replaced by a muscular stomach, which serves for mechanical grinding of food, while the glandular stomach serves for enzymatic action.

The digestive organs begin with the beak - this is the main organ for capturing food. The beak consists of an upper part (the mandible) and a lower part (the mandible). The shape and structural features of the beak are different in different birds and depend on the method of feeding. The tongue is attached to the bottom of the oral cavity; its shape and structural features depend on the nature of the food. The ducts of the salivary glands open into the oral cavity. Some birds have the enzyme amylase in their saliva and digestion of food begins in the oral cavity. Swallows and some swifts use sticky saliva when building nests; woodpeckers have insects stuck to their long tongue moistened with sticky saliva. Food moistened with saliva is easily swallowed and enters the esophagus, the lower part of which in many birds forms an extension - a crop (in which the food is soaked and partially digested). Further along the esophagus, food enters the thin-walled glandular stomach, in which numerous glands secrete digestive enzymes. Enzymatically processed food passes into the gizzard. The walls of the latter have well-developed strong muscles, thanks to the contraction of which food is ground. The ground food enters the duodenum, into which the ducts of the pancreas and gall bladder flow (birds have a two-lobed liver). The food then passes into the small intestine and then into the hind intestine, which is not differentiated into the colon and rectum and is significantly shortened. Through the hind intestine, undigested food remains are excreted into the cloaca.

Birds are characterized by high digestion intensity. For example, sparrows digest caterpillars in 15-20 minutes, beetles in about 1 hour, and grain in 3-4 hours.

Respiratory system. The respiratory organs begin with the nostrils, located at the base of the beak. From the mouth, the laryngeal fissure leads into the larynx, and from it into the trachea. In the lower part of the trachea and the initial sections of the bronchi there is the vocal apparatus of birds - the lower larynx. The source of sounds is the membranes that vibrate as air passes between the last cartilaginous rings of the trachea and the semi-rings of the bronchi. The bronchi penetrate into the lungs, branching into small tubes - bronchioles - and very thin air capillaries, which form an air-carrying network in the lungs. Blood capillaries are closely intertwined with it, gas exchange occurs through the walls of the latter. Some of the bronchial branches are not divided into bronchioles and extend beyond the lungs, forming thin-walled air sacs located between internal organs, muscles, under the skin and even inside hollow bones. The volume of the air sacs is almost 10 times the volume of the lungs. The paired lungs are small, are densely spongy bodies, and not bags, like in reptiles, and have little extensibility; they grow into the ribs on the sides of the spine.

In a calm state and while moving on the ground, the act of breathing is carried out due to the movement of the chest. When inhaling, the chest bone lowers, moving away from the spine, and when exhaling, it rises, approaching it. During flight, the sternum is motionless. When the wings are raised, inhalation occurs due to the fact that the air sacs stretch and air is sucked into the lungs and sacs. When the wings lower, exhalation occurs, oxygen-rich air moves from the air sacs into the lungs, where gas exchange takes place. Thus, oxygenated air passes through the lungs both during inhalation and exhalation (so-called double breathing). Air sacs prevent the body from overheating, as excess heat is removed with air.

Excretory system. The excretory organs are represented by two large kidneys, constituting 1-2% of body weight; they lie deep in the pelvis on both sides of the spine. There is no bladder. Through two ureters, uric acid in the form of a white mushy mass flows into the cloaca and is excreted out along with excrement without remaining in the body. This reduces the bird’s body weight and is important during flight.

Circulatory system. The heart of birds is relatively large, its mass making up 1-2% of body weight. The intensity of the heart is also high: the pulse at rest is 200-300 beats per minute, and in flight - up to 400-500 (in medium-sized birds). The large volume of the heart and rapid pulse ensure rapid blood circulation in the body, intensive oxygen supply to tissues and organs and removal of metabolic products.

In the structure of the heart, noteworthy is the complete division of the heart by a longitudinal continuous septum into the right venous and left arterial halves. Of the two aortic arches, only the right one, originating from the left ventricle, is preserved. The large and small circles of blood circulation are completely separated. The systemic circulation begins from the left ventricle and ends in the right atrium; arterial blood is carried through the arteries throughout the body (all organs are supplied only with arterial blood), venous blood through the veins enters the right atrium, and from it into the right ventricle. The pulmonary circulation begins from the right ventricle and ends in the left atrium. Venous blood through the pulmonary arteries enters the lungs, is oxidized there, and arterial blood through the pulmonary veins enters the left atrium, and from it into the left ventricle and into the systemic circulation. As a result of the fact that arterial and venous blood do not mix, the organs receive arterial blood. This enhances metabolism, increases the vital activity of the body, and causes a very high and constant body temperature of birds (42-45 ° C). The constancy of body temperature and its independence from environmental temperature is an important progressive feature of birds and mammals compared to previous classes of animals.

Nervous system. The brain has relatively large hemispheres and optic lobes, a well-developed cerebellum, and very small olfactory lobes. This is associated with more complex and varied behavior and the ability to fly. All 12 pairs of cranial nerves arise from the brain.

Of the sense organs, vision is the best developed. The eyeballs are large, allowing the retina to capture large images with clear detail. The eye has three eyelids - the upper, lower and transparent inner, or nictitating membrane. Accommodation (focusing the eye) is carried out by changing the shape of the lens and simultaneously changing the distance between the lens and the retina, as well as some changing the curvature of the cornea. All birds have color vision. The visual acuity of birds is several times higher than the visual acuity of humans. This property is associated with the enormous importance of vision during flight.

The hearing organ is anatomically similar to the hearing organ of reptiles and consists of the inner and middle ear. In the inner ear, the cochlea is better developed, and the number of sensitive cells in it is increased. The cavity of the middle ear is large, the only auditory bone - the stapes - is of a more complex shape, it is more mobile when the dome-shaped eardrum vibrates. The eardrum is located deeper than the surface of the skin; a canal leads to it - the external auditory canal. Birds have very acute hearing.

Compared to reptiles, birds have an increased surface area of ​​the nasal cavity and olfactory epithelium. Some birds (ducks, waders, carrion-eating predators, etc.) have a well-developed sense of smell and are used when searching for food. In other birds, the sense of smell is poorly developed.

The taste organs are represented by taste buds in the mucous membrane of the oral cavity, on the tongue and at its base. Many birds distinguish between salty, sweet and bitter.

Reproductive organs. The male has two testes, the vas deferens form a small expansion in the lower part - the seminal vesicle - and flow into the cloaca. The female has only one left ovary and a left oviduct, which flows into the left side of the cloaca. Fertilization is internal and occurs in the initial part of the oviduct. Due to the contraction of the walls of the oviduct, the fertilized egg moves towards the cloaca. In the oviduct there are protein glands and glands that form on the egg a two-layer leathery subshell shell, a porous calcareous shell and a thin supershell shell. The latter protects the egg from microorganisms.

The egg moves through the oviduct for 12-48 hours and is successively covered with a thick albumen, subshell, shell and supra-shell membranes. At this time, the development of the embryo occurs. At the moment the egg is laid, it looks like a germinal disc, which is located on the surface of the yolk. Two convoluted protein cords - chalazae - go from the inner shell to the yolk and support the yolk so that the embryonic disk is on top, closer to the body of the bird that incubates the egg. For egg development, a temperature of 38-39.5 °C is required. The duration of incubation varies among different birds: from 12-14 days for small passerines to 44-45 days for the golden eagle and almost two months for large penguins, albatrosses, and vultures. In different species of birds, the eggs are incubated by the female, the male, or both in turn. Some birds do not incubate eggs: the sandpiper in Turkmenistan buries its eggs in hot sand, the weedy (or big-footed) chickens of Australia and the Malay Archipelago lay them in heaps of sand and rotting plants; during decay, the heat necessary for the development of the embryo is generated.

Most birds incubate their eggs in a nest. Most often, birds build or weave nests from twigs, grass, moss, often fastening them with some additional material (hair, wool, clay, mud, etc.). The nest usually has raised edges and a recessed interior - a tray that holds the eggs and chicks. Thrushes, finches, and goldfinches strengthen their nests in the forks of branches on bushes and trees. In the wren and long-tailed tit, the nest has the form of a dense ball with thick walls and a side entrance, fixed in the fork of the branches. Larks and wagtails make nests on the soil, in a hole lined with grass. Woodpeckers, nuthatches, tits, flycatchers, and whirligigs nest in hollows, kingfishers, bee-eaters, and shore swallows nest in holes along river banks. Many swallows make a nest out of lumps of clay and mud, held together by sticky saliva. Rooks, crows, storks, and many daytime predators build nests from large twigs and branches. Seagulls, guillemots, and loons lay eggs in the sand and in depressions on rock ledges. Female ducks, geese, and eiders pluck the fluff on their abdomen and line their nest with it. Temperature fluctuations in nests are significantly less than in the environment; this improves incubation conditions.

According to the degree of physiological maturity of the chicks at the time of hatching, all birds are divided into two groups - brood and nestlings. In brood birds, immediately after hatching, the chicks are covered with down, sighted, can move around and find food independently. Adult birds protect the brood, periodically warm the chicks (this is especially important in the first days of life), and help in searching for food. This group includes Galliformes (grouse, hazel grouse, pheasants, partridges, quails, chickens), Anseriformes (geese, ducks, swans, eiders), cranes, bustards, ostriches. In nestling birds, the chicks are initially blind, deaf, naked or slightly pubescent, cannot move, and remain in the nest for a long time (in passerines - 10-12 days, in some birds - up to 2 months). All this time, their parents feed and warm them. This group includes pigeons, parrots, passerines, woodpeckers and many others. First, parents feed the chicks soft, nutritious food (for example, tits feed the chicks spiders in the first days). The chicks leave the nest feathered, almost reaching the size of adult birds, but with uncertain flight. For 1-2 weeks after departure, the parents continue to feed them. At the same time, the chicks learn to search for food. Thanks to various forms of caring for their offspring, the fertility of birds is much lower than the fertility of reptiles, amphibians and fish.

Extinct forms and phylogeny. All the features of birds that distinguish them from reptiles are primarily adaptive in nature. It is quite natural to believe that birds evolved from reptiles. Birds originate from the most ancient reptiles - pseudosuchians, whose hind limbs were built in the same way as those of birds. A transitional form - Archeopteryx - in the form of fossil remains (imprints) was discovered in Upper Jurassic deposits. Along with the features characteristic of reptiles, they have the structural features of birds.

Taxonomy. Modern forms of birds are divided into three groups: ratites (South American, African, Australian ostriches and kiwis), penguins and keels; the latter unite a huge number of species. There are about 30 orders of keelbirds. Of these, the most important are passerines, chickens, diurnal predators, Anseriformes, pigeons, etc.

Flights

Sedentary birds live in certain territories throughout the year, for example sparrows, tits, magpies, jays, crows. After the breeding season, nomadic birds make migrations over hundreds of kilometers, but do not leave a certain natural zone, for example, waxwings, bullfinches, redpolls, crossbills, and many owls. Migratory birds regularly fly to wintering grounds thousands of kilometers from their nesting sites along clearly defined flyways to other natural areas.

Migration is a seasonal phenomenon in the life of birds, which arose in the process of evolution under the influence of periodic changes in weather conditions associated with the change of seasons, intensive processes of mountain building over vast areas and sharp cold snaps in the Quaternary period. The long northern day and a large amount of animal and plant food contribute to the feeding of offspring. In the second half of summer in the northern regions, the length of daylight hours decreases, the amount of animal food (especially insects) decreases, the conditions for its production worsen, the birds' metabolic patterns change, which, with increased nutrition, leads to the accumulation of fat reserves (in American tree warblers before flying over sea ​​fat reserves account for up to 35% of the mass of birds). Many birds begin to unite in flocks and migrate to wintering areas. During migrations, birds fly at normal speeds, small passerines move 50-100 km per day, ducks - 100-500 km. The migrations of most birds take place at an altitude of 450-750 m. In the mountains, flocks of flying cranes, waders, and geese were observed at an altitude of 6-9 km.

Migration in some species occurs during the day, in others at night. The flight alternates with stops for rest and feeding. Migrating birds are capable of celestial navigation, i.e. to select the desired flight direction based on the position of the sun, moon and stars. The selected correct general direction of flight is adjusted according to visual landmarks: when flying, birds adhere to river beds, forests, etc. The direction and speed of migrations, wintering places and a number of other characteristics of birds are studied using their mass ringing. Every year, about 1 million birds are ringed in the world, including about 100 thousand in the USSR. A light metal ring with the number and symbol of the institution that carried out the ringing is put on the bird’s leg. When a ringed bird is caught, the ring is removed and sent to Moscow to the Ringing Center of the USSR Academy of Sciences.

The meaning of birds

Birds are of great economic importance, as they are a source of meat, eggs, down, and feathers. They destroy pests of fields, forests, orchards and vegetable gardens. Many species of domestic and wild birds suffer from psittacosis, a viral disease that can also infect humans. Birds living in the taiga, along with mammals, represent a natural reservoir of the taiga encephalitis virus. Birds living in Central Asia, along with mammals and reptiles, can be a natural reservoir of tick-borne relapsing fever pathogens.

However, not a single bird can be considered only useful or only harmful; it all depends on the circumstances and time of year. For example, sparrows and some granivorous birds feed on the seeds of cultivated plants and can peck juicy fruits in gardens (cherries, cherries, mulberries), but feed their chicks on insects. Feeding chicks requires a particularly large amount of food. The great tit brings food to the chicks up to 400 times a day, while destroying up to 6 thousand insects. The pied flycatcher collects 1-1.5 kg of insects, preferably small caterpillars, to feed six chicks over 15 days. During the autumn migration, the blackbird destroys a lot of blackbird bugs in forest belts and bushes: blackbird bugs during this period make up up to 74% of the total number of insects in the stomachs of blackbirds. Especially many harmful insects on agricultural crops and in forest plantations are destroyed by tits, flycatchers, nightingales, swallows, nuthatches, swifts, shrikes, starlings, rooks, woodpeckers, etc. Insectivorous birds eat many mosquitoes, midges, and flies that carry pathogens. Many birds (larks, pigeons, tap dancers, goldfinches, partridges, quails, bullfinches, etc.) feed on weed seeds, clearing fields of them. Birds of prey - eagles, buzzards, falcons (falcons, saker falcons, kestrels), some harriers, as well as owls destroy large numbers of mouse-like rodents, some feed on carrion and, thus, are of no small sanitary importance.

Under certain conditions, some bird species can be harmful. In particular, the bee-eater near apiaries feeds on bees, but in other places it destroys many harmful insects. The hooded crow eats the eggs and chicks of small birds, but also feeds on insects, rodents, and carrion. The goshawk, sparrowhawk, and marsh harrier destroy a large number of birds, in particular, the marsh harrier - chicks of waterfowl. One rook eats more than 8 thousand larvae of cockchafers, click beetles, and beet weevils per season, but in the spring, rooks pull out seedlings of corn and some other crops, so crops have to be protected from them.

Bird strikes sometimes cause serious accidents in jet and propeller-driven aircraft. In the areas of airfields, birds have to be scared away (in particular, by broadcasting recorded distress calls or alarm calls).

By making transcontinental flights, birds contribute to the spread of pathogens of certain viral diseases (for example, influenza, ornithosis, encephalitis, etc.). However, most birds can be considered beneficial. Many birds serve as objects of sport or commercial hunting. Spring and autumn hunting is permitted for hazel grouse, wood grouse, black grouse, pheasants, partridges, ducks and other birds. On the islands and coasts of the Arctic Ocean, light and warm eider down is collected, which eiders use to line their nests. Down is used to insulate the clothing of pilots and polar explorers.

Poultry farming

Poultry farming is an important branch of agriculture, developing rapidly. Chickens are bred at poultry factories and poultry farms (egg-laying breeds - Leghorn, Russian White, Oryol; egg-meat breeds - Zagorsk, Leningrad, Moscow), geese, ducks, and turkeys. Tens of thousands of eggs are laid in incubators at a time. Feeding, collecting eggs, maintaining the required temperature and light, cleaning processes, etc. mechanized and automated.

Bird conservation

To increase the number of beneficial birds, it is necessary to create favorable conditions for their nesting, for example, mixed forest plantations with a varied shrubby undergrowth, planting clumps of shrubs in parks and gardens. By hanging artificial nesting boxes (birdhouses, nest boxes, etc.), you can increase the number of tits, flycatchers, starlings and other birds by 10-25 times. In winter, it is recommended to feed sedentary birds by installing feeders on window sills, in front gardens, gardens, and parks. You should not disturb birds during the nesting period, destroy nests or collect eggs. During the hatching period, bird hunting is prohibited. Birds should also be protected in their wintering areas. State reserves and sanctuaries are of great importance in the protection of birds. For some rare and endangered bird species (for example, the white crane, etc.), measures are being developed for artificial maintenance and breeding in nature reserves.