Initially, naturalists claimed that there were between 9,000 and 10,000 species of birds on the planet. However, recent studies have doubled this number to about 18,000 species, with the possibility of more species appearing in the future. Birds are generally very mobile, migratory and live in many regions of the world. For this reason, bird researchers believe that there are more bird species yet to be discovered. The American Museum of Natural History has offered the latest number of bird species, urging researchers to work and document the "hidden" diversity of this animal class. According to the Museum, one of the reasons for the confusion is that there are species of birds that are very similar to each other and, if not carefully studied, they will be erroneously classified as members of the same species.
Why is the number of bird species doubling?
The number of species has increased due to miscounting, as well as the discovery of more new species. Scientists considered birds to be among the most studied organisms, with 95% of the described species. However, according to the American Museum of Natural History, scientists have used an incorrect checklist known as the "species concept" that limits the number of bird species that can interbreed. George Barrowkle, Associate Curator of the Museum, argues that this approach is obsolete as it is not even used in taxonomic classification outside of bird species. Barrowcle advocates a more thorough study of birds through the prism of morphology, where the main role is played by physical properties, such as color, plumage pattern, and other traits that may reveal the evolutionary history of species. Using this method would probably double the number of known bird species.
Some bird species are endangered
owls
Owls are one of the most confusing and unimportant birds. There are over twenty species of owls, and there is a strong possibility that more will be discovered in the future. Here are examples of some species of owls: great horned owl, snowy owl and barn owl. Interestingly, in many Asian and African cultures, the mention of owls symbolizes a bad omen and is often associated with death.
During the day, owls skillfully merge with their own. Other species such as the wood owl ( Heteroglaux blewitti), which is shy and docile at first glance, can become aggressive when hungry and catch prey twice its size. Owls tend to be territorial birds and cannot abandon their homes even when faced with danger. This factor and the cultures of individual peoples are the main reasons for the decline of the owl population.
bearded bustard
Bearded bustard ( Hobaropsis bengalensis) is found in only two regions worldwide, in the Cambodian grasslands and forests at the foot of the Himalayas. There are less than 1,000 adults of this species, which is why the Cambodian government has created a special guard to protect the birds. Conservation efforts are also bringing farmers from nearby villages together to implement wildlife-based approaches.
Wherever we are - in the forest or in the field, in big city or on a deserted sea coast, we will definitely meet birds. Well, if you ask any of you: how many species of birds do you know? How many varieties can you confidently distinguish in nature and correctly name? You can be sure in advance that this number will not exceed, at best, one or two dozen.
Meanwhile, more than 700 species of birds live on the territory of our Motherland! Surely many do not even know the names of the birds that will be discussed. Most of them are useful for humans. Some destroy pests - insects and rodents, others give us meat, fluff, eggs, others decorate forests, enliven parks, fill the world with songs, and this is also very important!
Imagine a spring forest in deathly silence, and you will understand that these are not empty words. Birds are our national wealth, our heritage, they need to be protected and loved. And for this, first of all, you need to know the birds, be able to distinguish them from each other, know where and how they live.
Here we will try to help you with this.
In the category “Birds by orders”, we will divide all the feathered inhabitants of Russia into groups - this way it will be more convenient to perceive information about a particular bird, its description, structure, size, habitat, nesting and breeding features.
To start general information about birds: body temperature averages 42.3 degrees Celsius (maximum 45.5 - in the smallest birds). The mass of birds has very wide limits - from a few grams, like a hummingbird, to almost 100 kilograms - these are ostriches. Due to the high level of metabolism necessary for survival (especially northern birds), they can absorb food per day with a total mass of up to 30% of their weight, and some eat food of the same weight as themselves.
They eat both plant and animal food. They reproduce by laying eggs. They have plumage and are mostly capable of flight. But there are exceptions (penguins, ostriches), but this is already a secondary phenomenon.
To date, there are more than 8,400 species of birds in nature, divided into forty orders. Almost 730 species of birds from 24 orders live, nest and settle on migrations in Russia.
Based on the reference book edited by Professor G.P. Dementieva.
- - warbler
- - finches
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Features of the structure and biology of birds
How many birds in the world
According to ornithologists, there are about 100 billion birds of about 8600 species in the world, and according to other sources - about 9000 species. Species of birds in tropical forests are especially diverse.
The smallest
The number of individuals of one species can be several tens or hundreds, for example, in the critically endangered American crane (Grus americana). Now the total number of the American crane already exceeds 300 birds. In the last century, the American crane inhabited the entire North American continent, from the forests of Canada to the Gulf of Mexico. But by the first third of the XX century. under the influence of anthropogenic transformation of landscapes and immoderate hunting, it disappeared from its former range. Only a small group of birds in the amount of 10-12 pairs has survived in the hard-to-reach forests of Northwestern Canada, in national park Wood Buffalo. 
white-backed albatrosses are also extremely rare. Now there are no more than 200 of them left in the world. The number of these inhabitants of the sea continues to decline - the ruin of at least one nest, the death of at least one bird from an accidental shot causes irreparable damage to the population.
The white-backed albatross was not always a rarity - for example, in the middle of the 19th century, more than 100 thousand birds lived on the island of Torishima in the East China Sea. On the southern islands of this sea, the main nesting sites of the albatross were located. But at the end of the last century, factory harvesting of feathers and down of these birds was organized in Japan. In just six years - from 1887 to 1903 - about 5 million albatrosses were exterminated. The destruction of birds continued into the twentieth century, and by 1940 only a few pairs of albatrosses remained on the island of Torishima. By 1978, only about 40 pairs of albatrosses were nesting on the island.
The most numerous species
The number of individuals of one species can reach many millions, like Wilson's storm-petrel (Oceanites oceanicus), an ocean bird, it can be considered the champion in terms of numbers among wild birds. This is a small bird, the size of a swallow, its body length is 15-19 cm, its wingspan is 40 cm. Its other name is Wilson's ocean trooper). 
The largest modern bird
This is an African ostrich (Struthio camelus). An adult male reaches a weight of 75 kg. Of these, the largest is considered to be the male of the North African subspecies, which reaches a height of 2.74 m. Its head and neck are 1.4 m long. Of course, such records are found only among individual specimens. In average, ostriches of this species reach a height of about 2 meters.
Male incubates
The male ostrich (Struthio) incubates the eggs. Several females lay eggs literally under his beak, and the male rolls them into the nest. Interestingly, in North Africa, there are from 15 to 20 eggs in a nest, in South America- up to 30, and in areas of East Africa - up to 50-60.
The largest wingspan of a wandering albatross Diomedea exulans, which lives in the southern oceans. It turned out to be 2.54 - 3.51 m, but the record is much higher. One old albatross had a wingspan of 3.63 m.
Hoatzin - a bird with claws on its wings x The Amazonian hoatzin (Opisthocomus hoatzm) looks like a common pheasant, with a yellowish crest, olive plumage on the back and a faded red on the belly. The young hoatzin has well-developed claws on the front fingers of the wings, indicating an ancient origin. When hoatzin chicks, deftly wielding their clawed wings, tear through branches, crawl on the ground or dive for tadpoles, they look like real small reptiles. Looking at them, one involuntarily recalls the image of the majestic Archeopteryx, a reptile bird from the Jurassic period. The hoatzin also retained other important archaic features: it does not scream like a bird, but croaks like a frog, and emits a strong muscular smell, like crocodiles and some species of turtles.
The heaviest Of modern flying birds, the bustard (Otis) is the heaviest. Its weight reaches 20 kg. The weight of the African bustard (Ardeotis kori), found in Northeast and South Africa, and the dudak bird (Otis tarda), found in Europe and Asia, are also worthy of note. Bustards weighing 19 kg and dudak weighing 18 kg are described, although there are unconfirmed reports of a male dudak weighing 21 kg, shot in Manchuria, which was too heavy to fly.
The largest
The modern flying bird is the Andean condor (Vultur gryphus), belonging to the suborder of American vultures. Males weigh on average 9-12 kg with a wingspan of 3 m or more (up to 5 m). The male California condor (Gymnogyps califomianus), stuffed at the California Academy of Sciences in Los Angeles, USA, is said to have weighed 14.1 kg in life. The condor lives in the American Cordillera. The condor feeds on carrion.
the highest and of the flying birds are the cranes, as well as the marsh birds of the order Gruidae. The growth of some of them reaches almost 2 m.
The smallest Male bee hummingbirds (Mellisuga helenae), living in Cuba and on about. Pinos, weigh 1.6 g, and their length is 5.7 cm. Half of the length is the tail and beak. The females are somewhat larger. Hummingbirds (Trochilidae) are not only tropical birds. They reach in their distribution in the north to Alaska and in the south to Tierra del Fuego. Another smallest bird is a bird with an English name. Little Woodstar, its Latin name is Acestrura bombus, which lives in Ecuador and northern Peru. Experts believe that the second bird is even smaller.
The smallest birds of prey... black-footed falcon-baby (Microhierax fringillarius) from Southeast Asia and white-breasted shrike (M. latifrons) from the northwestern part of about. Borneo. The average body length for both species is 14-15 cm, including a 5 cm long tail, and a weight of about 35 g.
Male albatross capable of circumnavigating the globe… covering a distance of 14,000 miles in just 46 days. On Bird Island in South Georgia, where the grey-headed albatross breeds, several birds were caught and attached to their feet. special devices- geolocators. With their help, scientists found that from the coast of South Georgia, the birds went to the southeast Indian Ocean, where tuna is being caught. More than half of the individuals then undertook a curious round-the-world trip - the fastest did it in just 46 days. Scientists were surprised to find that albatrosses fly so far and stay in the open sea for so long. 12 birds flew around the world, and three albatrosses - twice.
Birds are one of the most peculiar groups of animals. Zoologists consider them so different from other vertebrates that they are classified as a separate class - along with amphibians, reptiles and mammals. The plumage, characteristic appearance, wings and hard shell of eggs clearly separate this group from all other animals. Birds are amazingly diverse appearance which makes them, like butterflies, attractive to collectors. The lists compiled by bird watchers, which list the species they have encountered, have become an international symbol of amateur naturalists.
According to most ornithologists now, living birds are represented by about 8700 species, i.e. there are about 8700 various forms, which do not interbreed under normal conditions. They are divided into 27 orders and 170 families. However, experts disagree on the exact number of species in various genera. It is generally accepted that more than 5000 species are songbirds, and of the remaining species, 315-339 are parrots. There are 147 species of swans, geese and ducks, and only one species of the African ostrich. Among the best publications, including a detailed listing of orders and families of birds, can be called Word Atlas of Birds and Fundamentals of Ornithology. Evolutionary relationship between various groups birds are schematically represented on figure .
How many birds are on earth? It is generally accepted that more than 100 billion birds live on our planet, i.e. 25 times more than people. Accurate data exist for very few species. The most numerous, apparently, are ocean birds: many colonies of petrels, fulmars, little auks and puffins located on the islands number over a million individuals. The flock of slender-billed petrels in Australia alone is estimated to have consisted of 150 million birds. On several islands off the coast of Peru, 10 million cormorants and gannets nest. On the other hand, the number of some endangered species is very small.
Man becomes the most significant among the many factors that determine the number and distribution of birds. In the 300 years since the beginning of the technological revolution, accompanied by rapid population growth, almost 100 bird species have become extinct. According to the International Union for Conservation of Nature and Natural Resources, more than 150 bird species should now be considered endangered, rare or endangered.
How long do birds live? Roughly speaking, the larger the bird, the higher its age limit. Some birds live almost as long as humans. Owls, eagles and pelicans live in captivity up to 50-60 years and even more. Chickens and pigeons sometimes live into their thirties. Under natural conditions, birds, like other animals, rarely reach age limit. For example, the average life expectancy of a mallard, which is a commercial game, is only 11 months. Mortality is highest at an early age, even in non-hunted species. It is estimated that more than 25% of the eggs laid will hatch into chicks that live long enough to leave offspring. Predators are the main cause of death, but disease, bad weather, and accidents also cause serious damage.
Theoretically, each pair of birds is able to raise quite a lot of chicks during the season. If the reproduction of birds were not limited by many factors, their fecundity would very soon lead to the appearance of an enormous number of individuals. If, for example, each of the eight offspring of a pair of mallards survive and raise eight of their own chicks, and this continues, after 16 years the offspring of one pair will reach 300 billion, i.e. exceed the total number of all living birds.
The indisputable fact that the number of animals born exceeds the number of living ones served as one of the foundations of the theory of "natural selection" put forward by Charles Darwin. Individuals that manage to live long enough to leave offspring pass on to the next generation the genes that helped them survive. An example is often cited as a guillemot egg. One end of the egg of this sea bird is much wider than the other, so that the egg can roll only in a very small circle. Guillemots nest on narrow ledges of coastal cliffs, and many researchers believe that the described shape of the egg prevents it from falling off a cliff. For guillemots that lay rounder and therefore farther receding eggs, the probability of passing on their traits to offspring would be much lower.
The lifestyle of birds, their anatomy and physiology correspond to the conditions in which it lives this species. The main external adaptations - the shape of the beak, paws and wings - help determine the ecological niches of the species: the mobile beak of the flamingo, the location of the fingers of the woodpecker and the wide wings of the vulture - these signs exactly correspond to the characteristics of the life of these birds, allowing them to avoid competition with close species.
The physical and geographical features of the area and the climate (topography, soil types, water sources, temperature fluctuations and annual rainfall) determine the nature of the vegetation of the area. Everything is made up of a habitat (river bank, prairie, tropical rainforest, etc.) in which certain types of animals exist. The habitat can be compared with the "address" of the species, and the ecological niche - with its "profession".
The more we study natural biocenoses, the clearer becomes one of the important differences between natural ecosystems and those ecosystems that man has changed by adapting to his needs: man simplifies, and nature complicates relationships in communities. Man radically changes the course of evolution in any area, sharply reducing the number of possible ecological niches. In any garden, the number of plant and animal species is less than in a forest that previously grew in the same place.
The network of biological relationships in the forest is so complex and intricate that any misfortune that befalls one of the species of the community does not necessarily mean a tragedy for the rest of its members. In the systems that we create to provide ourselves with food, natural fibers and wood, there are no fine regulatory and compensatory mechanisms inherent in natural biocenoses.
It would seem that birds can avoid the consequences of human destruction of their habitats by flying to other areas. However, this is often not possible, especially for migratory birds whose migration routes have been fixed for millions of years. Our ability to destroy natural landscapes exceeds the ability of birds to escape the consequences of our intervention. The Meshchera region, where I now live, once abounded in swamps in spring and autumn and served as a haven for millions of migratory waterfowl. The draining of the swamps led to the creation of the fields of the Perovsky SPK and other agricultural organizations, but the noticeably reduced swamps could no longer feed even a small part of those ducks and geese, the huge flocks of which were hidden from the eyes of the sun a hundred years ago in the Vladimir Lakeside Meshchera. These birds did not fly away to "some other places" - they died of hunger, and the population of waterfowl greatly decreased ...
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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 intensive metabolism, a well-developed brain and complex behavior. All these features of birds allowed them to spread widely around the globe and occupy all habitats - land, water, air; they inhabit any territory from the high polar latitudes to the smallest oceanic islands.
The habitat was a selection factor in the evolution of birds (the structure of the body, 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 nomadic birds within their zone or settled 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, among which are 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 the rocks, forming bird colonies, where several species of birds not only live together, but also protect themselves from enemies.
Birds are characterized by a clearly defined dynamics of population change. Thus, the maximum of birds on Earth (up to 100 billion individuals) is observed after the emergence of young animals, the minimum - by the beginning of the next summer (a decrease in numbers up to 10 times). Human economic activity plays an important role in changing the number of birds. The areas of forests, swamps, meadows, natural reservoirs are reduced, 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 economic activity For humans, the importance of birds is mostly positive: they exterminate rodents, pests, seeds of weeds, which can be considered as a biological protection of fields and gardens. Birds must be protected and protected, fed, especially in winter, not to destroy their nests. Without birds - such bright, mobile, sonorous - our forests, parks, meadows, reservoirs become bleak, 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 collisions between birds and planes have become more frequent. Birds carry infectious diseases- influenza, encephalitis, salmonellosis, spread by ticks, fleas.
A man is engaged in poultry farming, breeding poultry, as well as ornamental and songbirds.
80 species of birds are listed in the Red Book of the USSR.
There are about 8600 species of birds in the world fauna, of which approximately 750 species are found within the territory of our country. Birds are distributed on all continents of the globe with the exception of the interior of Antarctica; some of them spend most of their lives on the high seas. On land, different types of birds are found everywhere where there is plant or animal food for them - in forests, shrubs, parks, forest belts, meadows, swamps, deserts, mountains and tundra.
Class characteristic
Birds are very similar in structure to reptiles and represent their progressive branch, the evolution of which followed the path of adaptation to flight. Often, birds are combined with reptiles in the group of lizards (Sauropsida). Birds are bipedal amniotes whose forelimbs have evolved into wings; the body is covered with feathers, the body temperature is constant and high.
The organization of birds is adapted to the conditions of flight. The body is compact, the skeleton is extremely light. Spread wings and tail form an area much larger compared to the area of the body. In the structure of the body of birds, one can note not only features characteristic of birds, but also signs common with reptiles. So, in the skin of birds there are no glands, with the exception of the coccygeal gland above the root of the tail. Some birds also lack this gland.
body integuments. The skin is very thin. There are horny covers on the beak, horny scales on the limbs, and claws on the fingers. Skin derivatives 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 the body of birds, help to keep warm (thermal insulation function), provide body streamlining, protect it from damage, form bearing planes in flight (wings, tail).
There are contour and down feathers.
contour 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 - beards. Parallel to one another, barbs of the first order depart from the rod, on both sides of which, in turn, numerous thinner barbs of the second order depart, the latter interlocking with each other 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 posterior edge of the skeleton of the hand; during the flight they form a thrust that carries the bird forward, to a lesser extent - lift. Secondary flight feathers are attached to the forearm, they form the main bearing surface of the wing. On the front edge of the latter there is a small wing with several short feathers that make it easier for the bird to land. The tail feathers are involved in flight control and braking.
down feathers they have a thin short stem 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 periodically (once or twice a year) molt, in place of old feathers they grow new ones.
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. Due to these features, the skeleton birds light and strong. There are five sections in the spine: cervical, thoracic, lumbar, sacral and caudal. The cervical vertebrae (from 11 to 25) are movably connected to each other. The vertebrae of other departments are fused together and motionless, which is necessary during the flight. The thoracic vertebrae are almost immobile, ribs are attached to them. The ribs have hook-shaped processes that overlap the adjacent posterior ribs. The thoracic vertebrae, ribs, and broad sternum, or sternum, form the ribcage. The sternum has a high crest below - the keel. A powerful musculature is attached to it and the sternum, moving the wing.
All lumbar and sacral (two of them) vertebrae fuse with each other and with the iliac bones; several caudal vertebrae join them, forming a complex sacrum characteristic of birds. It serves as a support for a pair of hind limbs that carry the entire weight of the body. There are 5-9 free caudal vertebrae; the terminal caudal vertebrae fuse into the coccygeal bone, to which the tail feathers are attached.
The girdle of the forelimbs consists of three paired bones: coracoids, shoulder blades and clavicles. The skeleton of the forelimb, which has turned into a wing, is significantly modified. The wing skeleton consists of one humerus, two bones of the forearm (ulna and radius), several bones of the hand (most of them merged 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, in connection with this they are also transformed. The hind limb girdle consists of three pairs of bones that fuse to form the pelvis. In the midline of the body, the pelvic bones do not fuse; 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 legs 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, which form the tarsus, and four fingers.
The skull is characterized by complete fusion of all bones up to the disappearance of sutures, 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 trunk 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 locks 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 the mechanical grinding of food, while the glandular stomach serves for enzymatic action.
The digestive organs begin with a beak - this is the main organ for capturing food. The beak consists of an upper part (upper beak) and a lower part (mandible). The shape and structural features of the beak different birds are different and depend on the type of food. 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 mouth. Swallows and some swifts use sticky saliva to build nests, while woodpeckers have insects sticking to a 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 - goiter (food is soaked and partially digested in it). Further along the esophagus, food enters the thin-walled glandular stomach, in which numerous glands secrete digestive enzymes. The food processed by enzymes passes into a muscular stomach. Strong muscles are well developed in the walls of the latter, due to the reduction of which the food is ground. The grated food enters the duodenum, into which the ducts of the pancreas and gallbladder flow (birds have a bilobed liver). Then the food enters the small intestine and further to the posterior intestine, which is not differentiated into the large and rectum and is significantly shortened. Through the posterior intestine, undigested food residues are excreted into the cloaca.
Birds are characterized by a high intensity of digestion. For example, sparrows digest caterpillars in 15-20 minutes, beetles - about 1 hour, grain - 3-4 hours.
Respiratory system. The respiratory organs begin with nostrils located at the base of the mandible. From the mouth, the laryngeal fissure leads to the larynx, and from it to the trachea. In the lower part of the trachea and the initial sections of the bronchi is the vocal apparatus of birds - the lower larynx. The source of sounds is the membranes vibrating during the passage of air between the last cartilaginous rings of the trachea and the half-rings of the bronchi. The bronchi enter the lungs, branch into small tubes - bronchioles - and very thin air capillaries that form an air network in the lungs. Blood capillaries are closely intertwined with it, gas exchange occurs through the walls of the latter. Part of the bronchial branches is not divided into bronchioles, goes 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. Paired lungs are small, are densely spongy bodies, not bags, as in reptiles, and are not very extensible; they grow to the ribs on the sides of the spine.
In a calm state and during movement on the ground, the act of breathing is carried out due to the movement chest When inhaling, the sternum descends, moving away from the spine, and when exhaling, it rises, approaching it. During flight, the sternum is immobile. When the wings are raised, inhalation occurs due to the fact that the air sacs are stretched and air is sucked into the lungs and sacs. When the wings are lowered, exhalation occurs, oxygen-rich air enters the lungs from the air sacs, where gas exchange takes place. Thus, oxygenated air passes through the lungs during both inhalation and exhalation (the so-called double breathing). Air sacs prevent the body from overheating, as excess heat is removed with the air.
excretory system. The excretory organs are represented by two large kidneys, which make up 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 outward along with excrement without lingering in the body. This reduces the body weight of the bird and is relevant when flying.
Circulatory system. The heart of birds is relatively large, its mass is 1-2% of body weight. The intensity of the heart is also high: the pulse at rest is 200-300 beats per 1 min, and in flight - up to 400-500 (for birds of medium size). A large volume of the heart and a frequent pulse ensure rapid blood circulation in the body, an intensive supply of oxygen to tissues and organs, and the removal of metabolic products.
In the structure of the heart, attention is drawn to the complete division of the heart by a longitudinal solid partition into the right venous and left arterial halves. Of the two aortic arches, only the right aortic arch is preserved, originating from the left ventricle. Large and small circles of blood circulation are completely separated. The systemic circulation begins in 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 in 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 does not mix, the organs receive arterial blood. This enhances metabolism, increases the vital activity of the organism, and causes a very high and constant body temperature of birds (42-45 ° C). The constancy of body temperature and its independence from the ambient temperature is an important progressive sign of birds and mammals in comparison with the previous classes of animals.
Nervous system. The brain has relatively large hemispheres and visual lobes, a well-developed cerebellum, and very small olfactory lobes. This is due to more complex and varied behavior and ability to fly. All 12 pairs of cranial nerves originate from the brain.
Of the sense organs, vision is the most developed. The eyeballs are large, which ensures receiving on the retina large images with clear details. There are three eyelids on the eye - the upper, lower and transparent inner, or nictitating membrane. Accommodation (focusing the eye) is carried out by changing the shape of the lens and a simultaneous change in the distance between the lens and the retina, as well as some change in the curvature of the cornea. All birds have color vision. The visual acuity of birds is several times higher than that of humans. This property is associated with great importance vision during flight.
The organ of hearing is anatomically similar to the organ of hearing of reptiles, it consists of the inner and middle ear. In the inner ear, the cochlea is better developed, the number of sensitive cells is increased in it. The cavity of the middle ear is large, the only auditory bone - the stirrup - is of a more complex shape, it is more mobile during fluctuations of the domed tympanic membrane. The tympanic membrane is located deeper than the surface of the skin, a canal leads to it - the external auditory canal. The hearing of birds is very acute.
Compared to reptiles, birds have an increased surface area of the nasal cavity and olfactory epithelium. In some birds (ducks, waders, predators that feed on carrion, etc.), the sense of smell is well developed and is used when searching for food. In other birds, the sense of smell is poorly developed.
Taste organs are represented by taste buds in the oral mucosa, 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 the left oviduct, which flows into the left part 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 shell membrane, a porous calcareous shell and a thin shell membrane. The latter protects the egg from microorganisms.
The egg moves along the oviduct for 12-48 hours and is successively covered with a thick protein coat, subshell, shell and suprashell membranes. At this time, the development of the embryo occurs. At the time of egg laying, it looks like a germinal disk, which is located on the surface of the yolk. Two twisted protein cords - chalase - go from the inner shell membrane to the yolk and support the yolk so that the germinal disc is on top, closer to the body of the bird that incubates the egg. Egg development requires a temperature of 38-39.5 °C. In different birds, the duration of incubation is different: from 12-14 days for small passerines to 44-45 days for golden eagles 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 alternately. Some birds do not incubate eggs: the oystercatcher in Turkmenistan buries its eggs in hot sand, weed (or large-legged) 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 formed.
Most birds incubate their eggs in the nest. Most often, birds build or weave nests from twigs, grass, moss, often fastening them with some additional material (hairs, wool, clay, mud, etc.). The nest usually has raised edges and a recessed interior - a tray that contains eggs and chicks. Thrushes, finches, goldfinches strengthen their nests in the forks of branches on shrubs and trees. In the wren and the long-tailed tit, the nest looks like a dense ball with thick walls and a side entrance, fortified in the fork of the branches. Larks, wagtails make nests on the soil, in a hole lined with grass. Woodpeckers, nuthatches, tits, flycatchers, wrynecks nest in hollows, kingfishers, bee-eaters, sand martins nest in burrows along river banks. Many swallows build their nests from lumps of clay and mud held together by sticky saliva. Rooks, crows, storks, many diurnal predators build nests from large knots and branches. Gulls, guillemots, loons lay their eggs in the sand, depressions on the ledges of rocks. Female ducks, geese, eiders pluck out fluff on their abdomen and line their nests. Temperature fluctuations in nests are much less than in environment; this improves the 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 chicks. In brood birds, chicks immediately after hatching are covered with down, sighted, can move around and find food on their own. Adult birds protect the brood, periodically warm the chicks (this is especially important in the first days of life), and help in the search for food. This group includes chickens (black 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, the parents feed the chicks soft nutritious food (for example, tits feed the chicks with 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. Due to various forms of care for offspring, the fecundity of birds is much lower than the fecundity of reptiles, amphibians and fish.
Extinct forms and phylogeny. All the features of birds that distinguish them from reptiles are predominantly adaptive to flight. It is natural to think that birds evolved from reptiles. Birds originate from the most ancient reptiles - pseudosuchians, in which the hind limbs were built in the same way as in birds. The transitional form - Archeopteryx - in the form of fossil remains (imprints) was found in the Upper Jurassic deposits. Along with the features characteristic of reptiles, they have signs of the structure of birds.
Systematics. Modern forms birds are divided into three groups: keelless (South American, African, Australian ostriches and kiwis), penguins and keels; the latter combine a huge number of species. About 30 orders belong to keeled birds. Of these, the most important are passerines, chickens, diurnal predators, anseriformes, pigeons, etc.
flights
Sedentary birds live in certain areas throughout the year, such as sparrows, tits, magpies, jays, crows. Migratory birds after the breeding season make migrations hundreds of kilometers long, but do not leave the boundaries of a certain natural zone, for example, waxwings, bullfinches, tap dances, crossbills, and many owls. Migratory birds regularly fly away for wintering thousands of kilometers from nesting sites along well-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, intense mountain building processes over vast areas, and sharp cold snaps in the Quaternary period. Long northern day and a large number of animal and plant food contribute to the breeding of offspring. In the second half of summer in the northern regions, the daylight hours are reduced, the amount of animal food (especially insects) is reduced, the conditions for its production worsen, the nature of metabolism in birds changes, which, with increased nutrition, leads to the accumulation of fat reserves (in American tree warblers, before flying over sea fat reserves are up to 35% of the mass of birds). Many birds begin to unite in flocks and migrate to wintering places. During migration, birds fly at normal speeds, small passerines move 50-100 km per day, ducks - 100-500 km. 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.
Flights in some species occur during the day, in others at night. The flight alternates with stops for rest and feeding. Migratory birds are capable of celestial navigation, i.e. to the choice of the desired flight direction according to the position of the sun, moon and stars. The selected correct general direction of flight is corrected according to visual landmarks: during flights, birds adhere to riverbeds, forests, etc. The direction and speed of migrations, wintering grounds and a number of other features of birds are studied using their mass banding. Every year about 1 million birds ring in the world, including about 100 thousand in the USSR. A light metal ring with a number and number is put on the bird's leg. symbol ringing agency. 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 orchards. Many species of domestic and wild birds suffer from psittacosis - viral diseases that humans can also become infected with. Birds living in the taiga, along with mammals, are 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, no bird can be considered only useful or only harmful, it all depends on the circumstances and the season. For example, sparrows and some granivorous birds feed on seeds of cultivated plants, they can peck juicy fruits (cherries, cherries, mulberries) in gardens, but they feed their chicks with insects. For feeding chicks, especially a lot of food is needed. The great tit brings food to chicks up to 400 times a day, while destroying up to 6 thousand insects. Pied flycatcher for feeding six chicks for 15 days collects 1-1.5 kg of insects, preferably small caterpillars. The blackbird during the autumn migration destroys a lot of bugs of the harmful turtle in the forest belts and thickets of bushes: the bugs of the harmful turtle during this period account for up to 74% of the total number of insects in the stomachs of thrushes. Especially many harmful insects on crops and in forest plantations are destroyed by tits, flycatchers, nightingales, swallows, nuthatches, swifts, shrikes, starlings, rooks, woodpeckers, etc. Insectivorous birds eat a lot of mosquitoes, midges, flies that carry pathogens. Many birds (larks, pigeons, tap dances, goldfinches, partridges, quails, bullfinches, etc.) feed on weed seeds, clearing the fields of them. Predator birds- eagles, buzzards, falcons (falcons, saker falcons, kestrels), some harriers, as well as owls destroy a large number of mouse-like rodents, some feed on carrion and, thus, are of great sanitary importance.
IN certain conditions some types of birds can be harmful. In particular, the bee-eater feeds on bees near apiaries, but in other places it destroys many harmful insects. Gray crow eats eggs and chicks small birds, but also feeds on insects, rodents, and carrion. The goshawk, sparrowhawk, marsh harrier destroy a large number of birds, in particular, marsh harrier - chicks of waterfowl. One rook eats more than 8 thousand larvae of May beetles, click beetles, beet weevils per season, but in spring rooks pull out seedlings of corn and some other crops, so crops have to be protected from them.
Bird strikes sometimes lead to serious accidents in jet and propeller-driven aircraft. In airfield areas, birds have to be scared away (in particular, by broadcasting recorded distress calls or alarms).
By making transcontinental flights, birds contribute to the spread of pathogens of certain viral diseases (for example, influenza, psittacosis, encephalitis, etc.). However, most birds can be considered useful. Many birds serve as objects of sport or commercial hunting. Spring and autumn hunting is allowed for hazel grouse, capercaillie, black grouse, pheasants, partridges, ducks and other birds. On the islands and coasts of the Arctic Ocean, light and warm eider down is collected, with which the eiders line their nests. Down is used to warm the clothes of pilots and polar explorers.
poultry farming
Poultry farming is an important industry Agriculture developing at a fast pace. In poultry farms and poultry farms, chickens are bred (egg-laying breeds - leghorns, Russian whites, Oryol; egg-meat - Zagorsky, Leningrad, Moscow), geese, ducks, turkeys. Tens of thousands of eggs are laid in incubators at the same time. Feeding, collecting eggs, maintaining the required temperature and light, cleaning processes, etc. mechanized and automated.
bird protection
To increase the number of useful birds, it is necessary to create favorable conditions for their nesting, for example, mixed forest plantations with a variety of shrub undergrowth, planting bushes in parks and gardens. Hanging artificial nesting sites (birdhouses, nest boxes, etc.) 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 placing feeders on window sills, in front gardens, gardens, and parks. Birds should not be disturbed during the nesting period, destroy nests and collect eggs. During the hatching of chicks, hunting for birds is prohibited. Birds should also be protected in their wintering areas. Of great importance in the protection of birds are state reserves and wildlife sanctuaries. For some rare and endangered bird species (for example, White Crane etc.), measures are being developed for artificial keeping and breeding in the conditions of nature reserves.
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