External and internal structure of birds

Sparrows belong to the class of birds. Birds are the most numerous class of terrestrial vertebrates, comprising about 8,600 living species, divided into about 35-40 orders. The birds' body is covered with feathers, and the forelimbs are turned into wings. On the territory of our country, 750 species from 18 orders are found - about 8.5% of the species of the world fauna. The geographical distribution of birds is extremely wide. They will populate the entire surface of the Earth and penetrate north to the pole. Some live sedentary lives, while others, with the onset of unfavorable conditions (low temperatures, drought, lack of food, etc.) can make long-distance migration flights. For each bird species, the time and routes of migration are strictly defined.

External structure of birds

The bird's body consists of a relatively small head, a long, mobile neck, and an ovoid body. During flight, the bird extends its head, presses it to its body or stretches its legs back - the whole body takes on a streamlined shape. On the head of the bird there is a beak, which consists of bony jaws covered with a horny sheath. Birds do not have teeth - this makes the bird's head lighter, which is of great importance when flying. With the help of their beaks, birds obtain food, build nests, and protect themselves from enemies. The shape and size of the beak varies among different birds and is associated with different methods of obtaining food. There are nostrils on the beak.

On the sides of the bird's head there are large eyes, which, in addition to the upper and lower eyelids, have a nictitating membrane. Below the eyes (closer to the back of the head) there are auditory openings hidden under the feathers. Some species of birds (pheasants, black grouse) have fleshy structures on their heads - combs and earrings. Almost the entire body of birds is covered with feathers. There are contour feathers on the outside, and down feathers underneath. Contour feathers seem to outline the body of the bird, creating a certain contour. The largest contour feathers form the flying surface of the wings. They are called flywheels. Large contour feathers of the tail are tail feathers. The contour feathers that cover the outside of the bird's body are smaller; they protect the bird's body from wind and rain. Down feathers protect the bird's body from cooling.

In addition to the feather cover, birds have horny scales on their bodies. They usually cover the lower part of the legs - the tarsus and toes. Feathers, horny scales, beak sheaths and bones are formed from the upper layers of skin. The skin of birds, like reptiles, is dry. Most bird species have only one gland, the coccygeal gland. It accumulates an oily liquid that birds use to lubricate their feathers.

Internal structure of birds

All birds are warm-blooded animals. Their body temperature is constant and quite high, 40-45 degrees. To maintain a high body temperature, especially during flight, birds must expend large amounts of energy. Therefore, their metabolism is very intense, especially in small species. The bird's four-chamber heart works under heavy load and is very developed. For example, in hummingbirds, the heart occupies half of the body cavity, and the volume is almost three times larger than the stomach. To ensure such a high level of vital activity, birds eat a lot of food. The birds have an excellent appetite. Some people eat more food per day than the bird itself weighs. Insectivorous birds fill their stomachs at least 5-6 times during the day. The speed of food digestion is very high - for example, a house sparrow digests a beetle within an hour, and a caterpillar in just fifteen minutes.

The digestive system of birds consists of the same sections and organs as those of other vertebrates. This is the oral cavity. Pharynx. Esophagus. Stomach. Small and large intestines and other organs. However, there are also differences. Many birds, especially granivores (pigeons, chickens, parrots) have a goiter - an enlargement of the esophagus. In the goiter, food is moistened by special secretions of the glands, under the influence of which it softens and undergoes some chemical change.

The stomach of birds consists of two sections: glandular and muscular. Digestive juices are released in the glandular section. Consuming large amounts of food and quickly digesting it provides the bird's body with a large amount of nutrients. When birds (especially small ones) starve, their body temperature drops and they quickly die, especially in winter, when the days are short and there is little time to search for food. That is why it is so important to feed the birds that remain with us for the winter.

The respiratory system of birds, like that of reptiles, consists of the respiratory tract and lungs. When you inhale, the air quickly passes through the lungs and immediately enters the breathing bags; when you exhale, the air from the bags again passes through the lungs, giving up a significant part of the oxygen. This type of breathing is unique to birds and is called double breathing. Double breathing is an adaptation to flight. The more often a bird flaps its wings, the more intensely it breathes.

The nervous system of birds differs from the nervous system of reptiles by the significant development of the brain. The forebrain hemispheres, midbrain and cerebellum are especially highly developed.

The complex behavior of birds is associated with the high development of the cerebral hemispheres. Birds choose places for nesting, build nests, protect nesting territories, hatch and feed chicks, make migrations, migrate, and they easily develop conditioned reflexes. The development of the midbrain is associated with the perfection of the visual organs, and the strong development of the cerebellum is associated with the coordination of the complex movements of the bird during flight. Many birds are capable of experiencing “emotions” - fear, anger, irritation, joy. The bird expresses its emotional state by the position of its plumage, the sounds it makes, and its posture. A person who has been interacting with a bird for a long time can always easily determine its condition by its appearance.

Birds have memory. Some “remember” for a short time - only three to four months. Others have a long memory. So, one parrot recognized its owner after nineteen years! Ravens and predators have particularly complex behavior. For example, crows distinguish a hunter with a gun from a man with a stick; a predator often waits on the opposite side of a bush for prey that has slipped into the bush.

Birds reproduce by laying eggs covered in a dense calcareous shell. All birds can be divided into two groups: chicks and brood birds. In nestling birds (passerines, woodpeckers, cuckoos, raptors, owls and many others), chicks hatch from eggs naked and often deaf and blind. The chicks of brood birds, having hatched from the egg, as soon as they dry out, are able to follow their parents and look for food. Brood animals include galliformes, anseriformes, cranes, gulls and others.

Order Passeriformes

The passeriformes order unites more than 5.1 thousand species, or almost 2/3 of all known bird species. Passerines are distributed throughout the globe - from the equator to the polar regions. Almost anywhere on the planet there are more birds of this order than any other. They inhabit forests and deserts, steppes, savannas and swamps, shores of reservoirs and highlands. Alpine jackdaws were observed even at the top of Elbrus.

At an altitude of 8,600 meters. You won't find passerines except in Antarctica. In Antarctica, in the highest latitudes of the Arctic and on some secluded ocean islands. However, in this order there are almost no real aquatic birds - none of them can swim, dive, or forage underwater. The only exception is the dipper, which also cannot be called aquatic passerine. They are more like a diver in a heavy spacesuit who is not able to swim, but can walk along the bottom.

The appearance of the members of this order is varied: small sunbirds weighing only 5 g and corvids weighing more than 1 kg, bright birds of paradise and modest warblers, birds with long and short straight and curved beaks and tails......

What unites them? All passerines build nests, their chicks are born naked and helpless and are completely dependent on their parents.

Even when after 10-20 days the chicks fledge and leave the nest, they continue to demand food from their parents for some time. Almost all representatives of this order form married couples, and the offspring are raised together. The responsibilities of partners are usually not evenly distributed. The male often builds the nest, and he also guards the nesting site, but the female spends more time incubating eggs, warming and feeding the offspring. At the end of summer and autumn, broods usually gather in flocks (sometimes numerous) and begin to roam over a vast territory. Most passerines of temperate and cold latitudes fly to the tropics for the winter, leaving only a few species that have adapted to foraging in harsh conditions. Already next spring, the overwintered youngsters are ready to have offspring themselves. Oddly enough, even small pichugas can live up to 10-15 years, and large corvids up to 20 years or more. Anatomical features include the presence of four toes on the feet, the first of which faces backwards. From 40 to 77 families are distinguished, they are grouped into two suborders - calling passerines and song passerines. This division is based on the structure of the vocal cords. In fact, there are good and bad singers among both. Passerines are the best singers among birds. Sometimes a bird can produce several notes simultaneously due to the special structure of the vocal cords: the left side of the larynx produces low notes, the right side produces high notes. In songbirds, the vocal apparatus is fully developed, there are 5-7 pairs of vocal muscles. The lower rings grow together into a bone drum - a resonator.

Screaming passerines inhabit mainly South and Central America; good vocalists are rare in the tropics. This is explained by the fact that the shiny surface of the wide leaves of the tropical forest reflects and distorts sounds, a complex song turns into a cacophony, but the sharp metallic notes sound very clearly. With song, males attract females and notify neighbors that the area is occupied. Song passerines are more widely distributed on the globe and have more widely inhabited temperate and cold latitudes. On the territory of Russia there are just over 300 species of passerines and 31 families from the order of songbirds.

Passerine family (Passeridae)

Tropical Asia and Africa are considered to be the homeland of the entire family. Here sparrows are the most diverse; many species have not lost touch with their natural habitat; they build spherical nests with a side entrance in trees, very much reminiscent of their closest relatives, the weaverbirds. In the peas and deserts of Central and Central Asia there are amazing sparrows - they nest in rodent burrows, in rock cracks, many of them resemble lark finches in their lifestyle and even in appearance. Most species are tireless flyers (they even fly in flight like larks, and on the ground they move not with springy jumps (like our sparrows), but by alternately rearranging their legs. In Russia there are 8 species of sparrows from five genera, In total, in the small family of passerines there are 8 genera with 33 -38 species.

Initially, these species lived in different regions. The house sparrow comes from the Mediterranean and the Middle East, the homeland of the field sparrow is obviously further east - in South Asia. Currently, both have spread following humans throughout a large part of Eurasia, and the brownie has spread almost throughout the entire world. The habitat continues to expand to the North and East. Sometimes in the villages of Siberia, sparrows freeze out entirely, but in the spring new ones arrive. In the mid-19th century, several pairs of sparrows brought from Europe were released in New York. Soon sparrows conquered almost the entire New World.

The sparrow is a very smart bird, it is not easy to catch and photograph it!

Sparrows usually nest in settlements, rarely in separate pairs. In the middle zone, couples form by the end of winter (each time anew), at this time there is excitement among the birds, the males chirp loudly and fight among themselves. The sparrow is lightly dressed for winter frosts and cannot spend the night in the open air in winter. It settles down where there is at least a little warmth, which is why it stays close to human habitation. Birds' nests are located in shelters, usually in the voids of wooden and stone buildings, behind platbands and cornices, sometimes in heaps of garbage, birdhouses, nest boxes, burrows, pipes, and swallow nests. They stuff the shapeless nest with rags, straw, and tow. From April to August, a couple manages to raise up to three broods, even in the Arctic – two. There are five to six chicks in one brood.

The female House Sparrow (Passer domesticus) looks brownish-gray with a brown back and a faint light eyebrow, and her beak is yellowish-brown. The male has a black beak, the underside of the body is lighter - pure gray, the top is brighter - sometimes chestnut, there is an ash-gray “cap” on the head, bordered on the side of the neck with a chocolate “bracket”, a black throat spot goes down to the chest. It has one light stripe on the wings. Their cheeks are grayish without black. Beautiful bird!

The tree sparrow (Passer montanus) is noticeably smaller than the house sparrow and can be easily distinguished by the color of its head. The chestnut cap is separated from the brown-motley back by a narrow white “collar”; there is a black spot on the white cheek and another small one on the neck. There are two light stripes on the wings. The male and female of this species are indistinguishable from each other.

The meaning of sparrows

Sparrows, as non-carnivorous birds, destroy pests of forests, gardens and vegetable gardens. Of course, they don’t think about which of the insects they eat are harmful and which are beneficial for humans. Along with pests, birds also destroy beneficial insects, but it is estimated that they destroy four to five times more harmful insects than beneficial ones, reducing their numbers by 45-75%. Scientists conducted special studies and found that birds, by eating agricultural and forestry pests, reduce losses from them by 28%. Research by scientists is also confirmed by a historical fact that occurred in the history of China. As we know, the main agricultural crop is rice.

The Chinese thought that sparrows were harming rice crops. A real war was declared on the sparrows: they were shot, caught with special traps, traps, and poisoned. Hundreds of millions of Chinese people began banging on pots in one day to scare away the birds with the noise. In the end, unable to land on the ground, the sparrows died. Each Chinese was obliged to hand over a certain number of killed birds, which were transported by trucks and wagons to landfills, and “finally” the day came when it was impossible to find more than a single sparrow throughout China. People won this unequal war…….. So what.

The first year the rice harvest was really good. And the Chinese still remember with shudder what happened next. Huge hordes of pests, multiplying and unpunished in the absence of the sparrow, turned the rice fields into barren deserts. One crop died, then a second, a third: famine set in. It was then that the Chinese realized what they had done by destroying all the sparrows. Birds began to be imported from other countries, specifically creating conditions for them to reproduce. This happens when a person mindlessly interferes, pursuing only momentary gain. In nature, everything is interconnected and any changes entail many others, the consequences of which may be unpredictable and dramatic.

Sparrows, like other birds, carry plant seeds. It cannot be said about the enormous aesthetic importance of birds, including sparrows, without which our life would be boring and silent.