Biology essay about birds. List of birds of prey: main characteristics of species

Bird class- warm-blooded animals, whose body is covered with feathers (the only group of animals), and the front limbs are turned into wings; hind limbs - legs. Birds fly beautifully, surpassing all other vertebrates in this respect. Also, birds move well on the ground, climb trees, many dive and swim in the water. Birds are extremely diverse in size, shape, color, habits and have adapted to living in various climatic conditions. There are about 9 thousand species.

The external structure of the bird

Birds have a head, neck, torso, limbs and tail. The head of the birds is small, it has a beak, eyes, nostrils. The beak is formed by bone jaws extended forward, which are covered with horn covers from above. Birds have no teeth, which makes the skull lighter. At the base of the upper part of the beak are the nostrils. Rounded eyes are covered with two eyelids and a nictitating membrane. Closer to the back of the head, ear holes are hidden under the feathers. The movable neck connects the head to the compact body.

Features of the body structure of a bird

signs	Features of the structure of the body of birds
body shape	streamlined
	Dry skin covered with horny feathers
Types of feathers	1. Contour - creates the shape of the body and helps with flight; 2. Down feather and down - keep warm
	Lightweight and durable due to: Fusions of bones (bones of the hand, pelvis, skull) Air cavities inside the bones Flight muscles are attached to the keel (breast bone)
	Large chest (lower wings); Subclavian (raise wings)
Digestive system	Digestion of food in 2-3 hours (rapid metabolism to maintain a constant body temperature) Beak --> pharynx --> esophagus (with goiter) --> stomach (from two sections - muscular and glandular) --> intestines --> cloaca
Respiratory system	Cellular lungs and additional air sacs in the body cavity and bones - to improve gas exchange and protect against overheating. Breathing is double.
Circulatory system	Four-chambered heart (two atria and two ventricles), two circles of blood circulation
Nervous system	The cerebellum is well developed; Developed hemispheres of the forebrain (complex behavior, instincts)
reproduction	Fertilization is internal, the female lays eggs containing a supply of nutrients for the embryo and protected by a calcareous shell and shell membrane
bird development	Spring: pair formation --> mating of males --> nesting --> laying eggs (from 1-2 to 15-20 pieces) --> incubation of eggs --> care for offspring. Chicks: 1. Brood - appear dressed in down, with open eyes and can leave the nest and follow the mother. 2. Nesting - appear helpless, with eyes fused for centuries, do not leave the nest for a long time.

Repeat the general characteristics and classification of the chordate type.

To study the aromorphoses of the class Birds. Write down in a notebook.

Study the structure of birds. Complete the outline in your notebook.

Consider stuffed birds of different types.

To study the external and internal structure of birds using the Dove as an example (dove dissection).

In the album, complete 7 drawings indicated in the printed manuals V (red tick). In the electronic manual, the drawings that need to be completed in the album are presented at the very end of the text.

In a notebook, write down and learn the classification of modern birds.

Draw and fill in table 1 in your notebook:

Table 1. The structure of a bird's egg.

Draw and fill in table 2 in your notebook:

Table 2. Variety of birds.

Know the answers to test questions themes:

General characteristics of the chordate type. Type classification Chordates.

Features of the organization of birds.

The systematic position, lifestyle, body structure, reproduction, significance in nature and for humans of the Dove.

General characteristics of birds

In modern animal taxonomy Birds(Aves) is a class in the phylum Chordata of the subphylum Vertebrata.

Basic aromorphoses(Aromorphoses are major evolutionary changes leading to a general complication of the structure and organization of the body) Birds are as follows:

the appearance of a four-chambered heart;
complete separation of arterial and venous blood flow;
perfection of thermoregulation;
the formation of spongy lungs;
progressive development of the nervous system;
ability to fly;
adaptive behaviour.

Birds are warm-blooded animals capable of flight. They settled all over the globe, populated a variety of places, and also mastered the air habitat. Currently, more than 8 thousand species are known, united in 35-40 orders.

Birds arose at the beginning of the Jurassic period (195 million years ago), and maybe a little earlier - back in the Triassic of the Mesozoic era (230 million years ago), from ancient reptiles, from which dinosaurs originated.

The structure of birds

The structure of birds is considered by example blue dove(type Chordates, subtype Vertebrates, class Birds, order Pigeons). blue dove lives in forests, mountains and cities, everywhere. Pigeons nest on trees, rocks, in buildings, hollows. They live in pairs, colonies. There are 2 eggs in the clutch. Both the female and the male incubate the eggs. Hatched chicks are naked, blind and require long-term parental care. The chicks are cared for by both parents, who first feed them on "goiter milk" and then regurgitate partially digested food for them. Already fully fledged chicks leaving the nests switch to feeding on grain. The gray dove is the ancestor of numerous breeds of decorative and carrier pigeons.

So, the body of streamlined birds consists of a small head, neck, torso and tail. The forelimbs are wings, the hind limbs are legs. On the head is a beak, consisting of a beak and mandible. The beak is covered with a horn sheath. At the base of the upper beak lie the openings of the nostrils, adjacent to them is an area of soft bare skin - a cere. On the sides of the head are large eyes, protected by the upper and lower eyelids and the nictitating membrane. Behind the eyes are external auditory openings. The neck is long and mobile.

Cover. The skin is thin, dry. The only skin gland located at the base of the tail (coccygeal) secretes a fat-like secret for lubrication

General characteristics of birds

feathers (elasticity, water repellency). The skin is covered with feathers (Fig. 1, 2).

The feather consists of a feather, a rod and a fan (Fig. 2). The fan is formed by barbs of the first and second order, which are connected by hooks, forming a closed plate. The contour feathers on the tail are called tail feathers, on the wings - flight feathers, and on the ventral and dorsal sides of the body - coverts. The plane of the wing is formed by two rows of contour, flight feathers, covered with covering feathers overlapping each other (streamlined body shape). Down feathers are located under cover feathers. The change of feather cover is accompanied by seasonal molting. Its functions: the acquisition of seasonal color, demonstration color during the mating season and thermoregulation. Areas covered with contour feathers alternate with areas of bare skin. Giving off excess heat, non-feathered areas protect the body from overheating. On the lower part (tarsus), the fingers are covered with horny shields.

The characteristics of the feathers are discussed in table 1.

Rice. 1. Types of feathers.

1 - contour pen; 2 - side lateral feather of the capercaillie; 3 - down feather; 4 - threadlike feather; 5 - seta; 6 - actually fluff.

General characteristics of birds

Rice. 2. The structure of the pen.

1 - fan; 2 - trunk; 3 - downy part of the fan; 4 - top hole; 5 - chin; 6 - bottom hole.

Table 1. Types of feathers in birds.

Pen Types	Structure
contour	They consist of a hollow rod to which fans are attached. The fan consists of beards of the first and second order. The latter have hooks that link them together.	Create bearing planes (wings, tail); form the contour of the body; protect the body from mechanical influences; have thermal insulation properties
	The rod is thin, there are no barbs of the second order - there is no closed fan	Thermal insulation
	The rod is shortened, and the beards move away from it in one bunch	Thermal insulation
filiform	Down feathers without barbs	Signal about air currents under the feather cover
	Feathers with an elastic core without beards. Found in the corners of the mouth of insectivorous birds that forage in the air	Enlargement of the trapping surface of the mouth

General characteristics of birds

Skeleton has structural features in connection with the adaptation to flight and walking on land only on the hind limbs. The lightness of the skeleton is provided by the pneumaticity of the bones (the presence of air cavities in the tubular bones). The strength of the skeleton is provided by the fusion of individual bones (sternum, complex sacrum).

The skeleton consists of an axial skeleton (spine), a head skeleton (skull), and a limb skeleton. The structure of the bird's skeleton is shown in Figure 3.

The spine is divided into five sections: cervical includes 14 movably connected vertebrae. thoracic consists of five vertebrae fused together. Together with the ribs and sternum, they form the ribcage. On the sternum there is an outgrowth - a keel, which increases the area of attachment of the pectoral muscles. Lumbar formed by six vertebrae, merged into one continuous bone plate. Sacral consists of two vertebrae. The last thoracic vertebra, all lumbar, sacral and anterior caudal (five) fuse with each other into a single complex sacrum. Tail consists of 15 vertebrae. The anterior five vertebrae are part of the complex sacrum, the middle six remain free, and the four posterior vertebrae merge to form the coccygeal bone (pygostyle), to which the bases of the tail feathers are attached.

Scull large, movably articulated with the spine with the help of one condyle. It consists of a large brain section and jaws covered with horny sheaths forming a beak (without teeth). The skull has a narrow base and closely spaced walls of huge eye sockets. There is an accretion of bones with the disappearance of the sutures of the skull (strength, lightness of construction).

limb skeleton includes belts and skeleton of free limbs. Shoulder girdle consists of three paired bones: scapula, clavicle and crow bones. Both collarbones fuse into a fork, giving the belt elasticity. Pelvic girdle durable, stable. Paired pelvic bones fused with the lumbar and sacral spine and the first tail vertebrae.

Skeleton of free limbs: the forelimbs are transformed into wings and consist of a shoulder, forearm and hand. The bones of the wrist and metacarpus merge to form a buckle. Of the fingers, only three are preserved - the second, third and fourth, while the third finger has two phalanges, and the second and fourth - one each. The hind limbs serve to move along the ground and consist of a thigh, a tibia (the fibula is rudimentary and adheres to the tibia) and a tarsus (fused bones of the tarsus and metatarsus). There are four fingers, three of them are directed forward, one is backward.

General characteristics of birds

Rice. 3. Pigeon skeleton (scheme).

1 - upper jaw; 2 - lower jaw; 3 - cervical vertebrae; 4 - shoulder; 5 - thoracic vertebrae; 6 - clavicle; 7 - crow bone; 8 - sternum; 9 - keel; 10 - lower leg; 11 - lantern; 12 - thigh; 13 - pelvis; 14 - coccygeal bone; 15 - tail vertebrae; 16 - ribs; 17 - forearm; 18 - brush; 19 - scapula; 20 - skull; 21 - toes.

General characteristics of birds

Rice. 4. The internal structure of a bird (pigeon).

1 - trachea, 2 - goiter, 3 - singing (lower) larynx, 4 - jugular vein, 5 - ventricles of the heart, 6 - right atrium, 7 - aorta, 8 - innominate artery, 9 - pulmonary arteries, 10 - lungs, 11 - liver, 12 - small intestine, 13 - pancreas, 14 - large intestine, 15 - cecum, 16 - cloaca, 17 - bag of Fabricius, 18 - ureter, 19 - kidney, 20 - testis, 21 - muscular stomach.

General characteristics of birds

The internal structure of the bird is shown in Figure 4.

Muscular system highly developed and differentiated. The most developed muscles of the chest, providing the movement of the wings. Paired pectoralis major, attached to the sternum and its keel, serve to lower the wing, subclavian muscles - to raise the wing. The long neck muscles provide complex head movements. Strongly developed muscles of the hind limbs are designed for movement on the ground.

Nervous system consists of the spinal cord and brain with nerves extending from them. The brain is represented by the following departments:

1. forebrain has developed cerebral hemispheres. Their surface contains a cluster of nerve cells that form the archipallium. However, most of the forebrain is formed by the striatum. There are no furrows or convolutions. The hemispheres regulate complex forms of bird behavior, the visual lobes are highly developed, and the olfactory lobes are poorly developed.

2. diencephalon poorly developed. On the upper side is the epiphysis, and on the bottom, behind the optic chiasm, is a large pituitary gland.

3. midbrain has well-developed visual tubercles.

4. Cerebellum well developed in connection with coordination of movements and balance during flight. Consists of an average share - a worm and two lateral protrusions. Behind covers the midbrain and part of the medulla oblongata.

5. Medulla passes into the spinal cord.

12 pairs of cranial nerves leave the brain.

Spinal cord has a thickening in the shoulder and lumbar regions, where nerves depart from it to the front and rear limbs, forming the brachial and pelvic plexus.

Sense organs. The leading ones are sight and hearing. organ of taste- taste buds in the throat. Olfactory organ poorly developed. Organ of vision very well developed. The eyeballs are large, located on the sides of the head. The field of view of each eye is 150°, and the field of binocular vision is 30-50°. Visual acuity is very high. The image on the retina is large, which allows you to distinguish the details of the object. The retina has a high density of photoreceptors, birds distinguish colors and shades. Accommodation (double) is carried out by changing the shape of the lens (under the action of the ciliary muscle) and simultaneous movement relative to the retina. In the area of the blind spot there is a vascular formation - a ridge, which is a source of nutrients and oxygen. The mechanical strength of the eyes is provided by the thickening of the sclera and the appearance of bone plates in it. The eyelids are well developed. There is a nictitating membrane (third eyelid). hearing organ developed

General characteristics of birds

well. Consists of the inner and middle ear. In the inner ear, the outgrowth of the round sac elongates and the number of sensory cells increases. In the middle ear, the dimensions of the tympanic cavity increase, the shape of one auditory bone, the stirrup, becomes more complicated, which increases its mobility. The size of the tympanic membrane increases. The Eustachian tubes open into the pharynx with one common opening. The rudiments of the outer ear appear, and there is an auditory canal ending in the tympanic membrane. Organs of skin touch- accumulation of sensitive cells that respond to changes in the position of feathers. Thermal detectors register changes in body temperature, consist of a cluster of sensitive cells, braided with nerve endings.

Digestive system associated with the characteristics of life processes. Warm-bloodedness and high mobility of birds require significant amounts of food and its rapid assimilation. Food in the gastrointestinal tract is quickly digested due to the activity of digestive enzymes and an increase in the absorptive surface of the intestine. The horny edges of the jaws form a beak, which serves to capture food. There are no teeth. The tongue is muscular, conical, has keratinized spines to hold food. Salivary gland ducts with digestive enzymes. The pharynx has a larynx with a respiratory system. The esophagus is long and easily extensible, its lower part forms a temporary receptacle for food - the goiter. The stomach is divided into two sections: glandular, with thick walls that secrete digestive juices; muscular, with an inner dense horny surface, where food moistened with digestive enzymes is mechanically processed by muscle contractions and crushed by pebbles (gastroliths).

The intestine is long, differentiated into the duodenum (the ducts of the liver and pancreas open), the small intestine, paired blind and short large intestine, ending in the cloaca. The rectum is very short, and undigested food remains, without accumulating, are quickly brought out. On the dorsal side of the cloaca there is a blind outgrowth - the bursa of Fabricius, which performs the function of an endocrine gland and is involved in the immune defense of the body. The liver is large, bilobed. The pigeon has no gallbladder.

Respiratory system consists of a complex system of airways and lungs. The airways include the nostrils, nasal cavity, nasopharynx, larynx, and long trachea. In the place where the trachea branches into the bronchi, there is a lower larynx, which is characteristic only of birds. It contains the vocal cords, which, when air passes through, vibrate and make sounds. The variety of sounds produced is controlled by the contraction of specific singing muscles. Lungs - dense spongy bodies, low extensibility, with a small volume. Consist of branched bronchial tubes. The main bronchus enters the lung and gives 15-20 branches (secondary bronchi), interconnected by parabronchi with numerous outgrowths (bronchioles), braided with a network of blood vessels.

General characteristics of birds

capillaries (gas exchange occurs). Part of the bronchial branches (4-5 bronchi) go beyond the lungs and form thin-walled extensions - air sacs located between the internal organs. By volume, they are about 10 times the volume of the lungs. There are paired air sacs (cervical, prothoracic, retrothoracic and abdominal) and unpaired air sacs (interclavicular). Outgrowths of air sacs penetrate into the cavities of large bones. The importance of air sacs: cooling and facilitating the body, "pumps" that pump air into poorly extensible lungs (gas exchange does not occur in the sacs). Chest breathing mechanism. With the expansion of the chest, inhalation occurs, with relaxation of the pectoral muscles and narrowing of the chest cavity, exhalation occurs. Unlike all terrestrial vertebrates, birds are saturated with oxygen through the lungs both on inhalation and on exhalation (the so-called double breathing).

Circulatory system closed, has two circles of blood circulation. The heart is four-chambered (the right half contains venous blood, the left half contains arterial blood), therefore arterial and venous blood are completely separated, which ensures a high metabolic rate (warm-blooded animals). Two independent vessels depart from the heart: the pulmonary trunk (carries venous blood) and the right aortic arch (arterial blood).

Small circle of blood circulation. The pulmonary trunk departs from the right ventricle, which, upon exiting the heart, divides into the right and left pulmonary arteries. Gas exchange occurs in the lungs, and oxygenated arterial blood flows through the right and left pulmonary veins into the left atrium.

Great circle of blood circulation. The right aortic arch departs from the left ventricle, which, when leaving the heart, is divided into two vessels: the right and left innominate arteries, each of which branches into the common carotid and subclavian arteries (brachial and thoracic). The right aortic arch curves around the heart and forms the dorsal aorta. All organs of the body are supplied with arterial blood. Venous blood from the back of the body is collected through the inferior vena cava and flows into the right atrium, after being purified through the portal system of the liver and kidneys. Venous blood from the anterior part of the body is collected in the anterior vena cava, which empty into the right atrium. The heart is large compared to the size of the body. A high rate of blood circulation through the vessels is provided by a high heart rate.

excretory system represented by the pelvic kidneys (metanephros, secondary kidney). The relative size of the kidneys in birds is large and is directly related to a very intensive general metabolism. The ureters depart from the kidneys, flowing into the cloaca. The end product of metabolism is uric acid. Urine passes through the excretory tract quickly due to the poor solubility of uric acid, the possibility of blockage by urinary salts of the conductive tract and is excreted in the form of white crystals along with litter. Related to this is the lack of

General characteristics of birds

bladder birds. The loss of water during urination in birds is small, since water is reabsorbed in the cloaca.

Sexual system. Dioecious. Sex glands are paired. In males, the bean-shaped testes, suspended from the mesentery, are located above the upper lobe of the kidneys. The size of the testicles varies with the seasons. By the breeding season, the volume of the testicles increases by 1500 times. Mild appendages are attached to the inner edges of the testicles, from which the vas deferens extend, located parallel to the ureters and flowing into the cloaca. In some species, the vas deferens, before flowing into the cloaca, form an extension - seminal vesicles (semen reservoir). There is no collective body. Fertilization is internal (in the upper parts of the oviduct), by bringing the openings of the cloacae of the female and male closer together. In females, the reproductive system consists of the left ovary and the left oviduct, which opens into the cloaca. The reason for the reduction of the right half, apparently, is associated with the laying of relatively large hard-shelled eggs. The ovary is granular, irregular in shape, located in front of the left kidney. Its value is different depending on the maturity (size) of the emerging eggs. The oviduct has the form of a long tube, one end of which opens into the cloaca, and the other funnel into the body cavity. The initial section of the oviduct is rich in glands that secrete protein, which covers the passing egg with a thick layer. In the next section, the egg is covered with shell membranes. In the uterus, a calcareous egg shell and staining of the suprashell membrane are formed. The last section of the oviduct (vagina) is short and has significant muscles, from which the egg enters the cloaca and then out. The entire period of passage of the egg through the oviduct is 41 hours for the pigeon.

Birds are amniotes, i.e. vertebrates whose embryos have embryonic membranes that ensure the development of the embryo in the ground-air environment.

Development in birds - direct. The female dove lays two eggs in the nest. According to the type of development, pigeons are nesting (nesting) birds. The development of the embryo begins as a result of warming the egg (incubation 16-19 days). As it develops, a feather cover appears, a beak, and the tail disappears. Before hatching, the chick breaks through the inner shells of the egg with its beak and breathes through the lungs in the air chamber. Then, with a tubercle on its beak, the chick pierces the egg shell and comes out of it. Hatched chicks are naked, blind and require long-term parental care. The chicks are cared for by both parents, who first feed them on "goiter milk" and then regurgitate partially digested food for them. Already fully fledged chicks leaving the nests switch to feeding on grain. The structure of the bird's egg is presented in table 2. The differences between chicks and brood chicks are described in table 3.

Seasonal phenomena in the life of birds. All birds can be divided into migratory, nomadic and sedentary. Migratory birds (ducks, geese, swallows) include species

General characteristics of birds

which migrate considerable distances from their nesting sites. Nomadic birds (woodpeckers, tits, bullfinches) do not make regular flights in strictly defined directions; they winter not far from nesting sites. Sedentary birds (rock dove, sparrows, jackdaws) migrate within the same area where they breed.

Ecology of birds. Birds are adapted to different habitats, which causes the emergence of ecological groups among them (Table 4). Each group is tied to its habitats, uses their own food and has certain adaptations for obtaining them.

Features of the adaptation of birds to flight: transformation of the forelimbs into wings; streamlined body, covered feathers; shaping of the sternum keel, with powerful muscles that control the wings; double breath, providing intensive metabolism; lightweight skeleton(hollow bones); weight loss due to the absence of the bladder, one ovary, teeth, rectum, copulatory organ; Availability high visual acuity and progressive development of the brain, in particular the cerebellum.

Table 2. The structure of the bird's egg.

	Structural elements
egg shells
Shell	Dense calcareous porous shell	Protective - from mechanical damage and penetration of bacteria. Ensuring gas exchange
Undershell shells	Formed by a network of organic fibers. The spaces between the fibers are filled with air	Ensuring gas exchange
air chamber	During gas exchange, the egg loses water. The evaporated water is replaced by gas, which forms an air chamber. The chamber passes into the space between the fibers of the shell membranes	Ensuring gas exchange (at a certain stage, the chick pierces the inner shell membrane and begins to breathe air from the chamber)

General characteristics of birds

Table 2. (end)

	Structural elements
	Consists of 87% water, 13% protein and other substances	Protective - from mechanical damage. Water source
Yolk (actual egg)	Composed of 50% water, 23% fat, 16% protein, 11% lipoid	Reserve - nutrients, water. Material for the formation of the embryo
Chalazy (cords)	Made up of dense protein	Ensuring the position of the germinal disc (shock absorbers)
Embryonic membranes
	The membrane that surrounds the embryo. Between the embryo and the amniotic membrane is the amniotic fluid that contains the developing fetus	Protective
Allantois	An outgrowth of the posterior intestine, into which metabolic products enter. Gradually increases and adheres to the shell. It develops blood vessels	Ensuring gas exchange
Serous membrane (serosa,	Outer germinal membrane	Trophic

General characteristics of birds

Table 3. Types of chick development.

Brood

Chicks

covered with down;

able to move

(a few hours after birth, they follow their parents);

are able to feed themselves;

masonry size is determined

the possibility of incubation masonry

Naked or almost naked;

unable to move;

unable to independently

feed;

masonry size is determined

opportunity to feed the chicks

Representatives: ostriches, galliformes, anseriformes, bustards, waders

Representatives: passerines, woodpeckers, pigeons, swifts, diurnal predators, owls

Table 4. Ecological groups of birds.

habitats		Representatives
birds of the forest	Tit, pika, wren, nuthatch		Thin strong beak. Tenacious and sharp claws, long fingers. Stiff tail feathers. migratory
	Great spotted woodpecker		Chisel-shaped beak, long, thin and hard tongue. Long, tenacious fingers (two pointing forward and two back). Tail feathers are hard and elastic. Feeds on insect larvae, in winter - seeds of coniferous plants. settled

General characteristics of birds

Table 4. (continued)

habitats			Representatives			Features of the structure and nutrition
birds of the forest		Hazel grouse, black grouse, capercaillie, pheasant, partridge			Spend a lot of time on the ground. Scaly fringes (in hazel grouse), feathers (in partridges) help to stay on the snow without falling through. Strong legs armed with large claws; three fingers help to rake the forest floor. A strong, bent down beak helps to bite buds, berries, young shoots of plants. Wings short and wide
birds of the forest					The beak, similar to crooked scissors, is designed to peel seeds from cones of coniferous trees.
Birds open air spaces		Swallow, swift, nightjar			Long, narrow wings, notched tail - the steering wheel when flying. The beak is small, with a large mouth funnel of bristle-like feathers at the corners of the mouth. The legs are short, tightly pressed to the body during flight. They feed on insects in the air. migratory
Birds of the steppes and deserts		Bustard, African ostrich, little bustard, crane			Omnivorous. The coloration is protective, they nest on the ground. The coccygeal gland is poorly developed. The huge paw of the flightless African ostrich has only two fingers. Long legs, neck and beak. Migratory (order Cranes)
Birds open plots reservoirs	Duck, goose, swan, night heron, grebe			They swim well, many dive. The body is flattened, the legs are shifted far back, with webbed fingers. The plumage is dense, the coccygeal gland is well developed. The beak is flattened, with horny teeth along the edges. migratory
Birds of coasts, ponds and swamps	Stork, heron, sandpiper, bittern			Long thin legs (very long fingers and small webs) and neck, long beak (compressed laterally). They feed on frogs, fish, mollusks, worms, and insects. They nest on the shore, not far from the water, some make their nests in trees. migratory

General characteristics of birds

Table 4 (end)

habitats	Representatives	Features of the structure and nutrition
sea birds	Seagull, murre, water cutter, puffin, cormorant	They form bird markets on steep cliffs, feed on fish. Beak-tongs or beak-harpoon for catching fish from the air and under water. settled
Predator birds	Eagle, falcon, vulture, hawk, kite, owl	Predators. Excellent vision, powerful wings, sharp curved claws and a hooked beak. Many birds of prey can soar for a long time using the warm currents of rising air. settled

"Class - Birds"

Birds are highly organized vertebrates. The ability for long-term flight, warm-bloodedness and other features of life gave them the opportunity to spread widely on Earth. The life of birds is associated with meadows, fields, swamps, banks of reservoirs, open areas of water. However, most of their species are forest dwellers. In the crowns of trees and shrubs, tits, kinglets, crossbills are common, on tree trunks - woodpeckers, nuthatches, pikas, on the ground - black grouse, hazel grouse, capercaillie. In terms of the number of species, the class of birds is the largest among terrestrial vertebrates (about 9 thousand species).

Features of the structure and life of birds

The ability to fly, along with other modes of movement, determined many specific features of the external and internal structure of birds.

External building. Birds have a relatively small head, a long movable neck, and a compact body. On the head there is a beak, consisting of bone jaws and horn covers. The nostrils are located on the mandible. Large eyes have movable eyelids and a nictitating membrane. On the head (closer to the back of the head) are the auditory openings.

The body of birds is covered with feathers: contour, down, down. The contour feather consists of a rod, a dense plate - a fan, a free part of the rod - an ochin. The fan is formed by barbs of the first and second order, interlocking with each other by microscopic hooks of barbs of the second order. The downy feather does not have a dense fan. Down - feathers with a very short stem and a bunch of beards extending from it. Contour feathers streamline the body of the bird, protect from the wind. The largest of them form the flying surface of the wings (primary feathers) and tail (tail feathers). Down feathers and down prevent heat transfer. Birds restore the integrity of split webs with their beaks, lubricate them with fat. Worn out feathers are replaced with new ones during the seasonal molts.

The skin of birds is thin and dry. Most have only the coccygeal gland (produces an oily liquid with which birds lubricate feathers). On the legs of birds there are horny scales.

Skeleton features. The skeleton of birds is light (most of the bones are filled with air) and strong (many bones fuse together in the early stages of embryonic development). The cervical region includes from 11 to 25 vertebrae (the head can turn almost 180 degrees). The thoracic vertebrae are fused together. With the ribs and sternum, they form the ribcage. Most birds have an outgrowth on the sternum - a keel. It increases the area of attachment of the pectoral muscles.

The last thoracic vertebra, all the lumbar, sacral and anterior caudal vertebrae are fused into a complex sacrum. The tail section consists of several movably connected vertebrae and vertebrae that form the coccygeal bone, which serves as the site of attachment of the tail feathers.

In the skeleton of the wing, 3 underdeveloped fingers were preserved, the small bones of the hand fused into a single bone - a buckle. The girdle of the forelimbs consists of paired shoulder blades, clavicles (fused at the lower ends) and crow bones. In the skeleton of the legs, several small bones of the foot have grown together into a single bone - the tarsus, which allows the bird to walk. The belt of the hind limbs - the pelvis is formed by two pelvic bones fused with a complex sacrum.

Musculature of birds. Muscles in birds have reached a high development, especially the pectoralis major muscles that lower the wings. In good flyers, they make up 1/5 of the body weight. Among the muscles of the hind limbs (up to 35 individual muscles) there are muscles with long tendons. When a bird sits on a branch, the tendons stretch and squeeze the fingers.

Features of the structure of the organs of the body cavity. The esophagus in many birds has an expansion - goiter, where food accumulates, softens and is partially digested. The stomach consists of two sections: glandular and muscular. In the glandular, food is processed by digestive juices, in the muscular, it is ground with small pebbles swallowed by birds. The large intestine is short and the birds defecate frequently (an adaptation to relieve body weight). Birds have a cloaca.

The lungs of birds are dense spongy bodies. Air passes through the trachea, two bronchi, which branch and end in thin-walled bubbles, braided with capillaries. Part of the branches of the bronchi extend beyond the lungs and form air sacs, the main role of which is to participate in the breathing mechanism during flight. When the wings rise, the volume of the body cavity increases, which leads to stretching of the air sacs. In this case, air from the lungs passes into the anterior air sacs, and air from the external environment through the respiratory tract goes into the lungs and into the posterior air sacs. During this time, gas exchange takes place in the lungs. When the wings are lowered, the volume of the body cavity decreases and, under the pressure of the internal organs, the air containing a lot of oxygen passes from the rear air sacs into the lungs, and the air from the anterior sacs into the trachea and is discharged outside. Thus, air passes through the lungs both when inhaling and when exhaling. The more intense the flight, the better the lungs are ventilated. When moving on land and at rest, breathing in birds occurs without the participation of air sacs.

Birds have a four-chambered heart (two atria and two ventricles). The large and small circles of blood circulation are completely separated (arterial blood enters the systemic circulation from the heart, and venous blood enters the small circle). The speed of blood circulation in birds is extremely high, which is associated with a high frequency of heart contraction.

The excretory organs of birds are bean-shaped kidneys. The resulting urine flows down the ureters into the cloaca and is excreted with feces.

Metabolism. Perfect breathing, the consumption of a large amount of food and its rapid digestion, a high heart rate and a rapid supply of nutrients and oxygen to tissues ensured a high metabolic rate in birds. Thanks to the feather cover, the release of heat to the external environment significantly decreased and the temperature of the birds became high (up to 43 ° C) and constant.

Nervous system. In birds, the hemispheres of the forebrain, midbrain and cerebellum are highly developed. With the development of the hemispheres of the forebrain, the rapid formation of various conditioned reflexes is associated, with the midbrain, the improvement of vision, with the cerebellum, the coordination of complex movements, especially during flight. The behavior of birds is very complex, which is manifested in the choice of nesting sites, building nests, protecting nesting territories, breeding and feeding chicks, the relationship of adults with each other, etc.

Reproduction and development of birds

Features of the reproductive organs. In females of most birds, the right ovary is underdeveloped and only the left one functions. The eggs in the ovary do not mature at the same time. The developed egg, passing through the oviduct, is fertilized by sperm introduced by the male into the female's cloaca.

The structure of the egg. Most of the egg is occupied by the egg itself - the yolk with the germinal disc (always facing up). After fertilization, the yolk is covered with protein, a two-layer subshell membrane (at the blunt end of the egg it exfoliates and forms an air chamber), a calcareous shell with numerous pores, and the thinnest suprashell membrane that protects the egg from the penetration of microbes.

Embryo development. The females of most birds lay their eggs in pre-built nests. A nest, even a hole in the soil, contributes to the compact arrangement of eggs, the preservation of heat and air humidity under the incubating bird. The development of the embryo in the egg occurs at a high temperature (about 39 ° C) and a certain humidity. The formed chick sticks its beak into the air chamber and inhales the air. It has a horny tooth on its beak. After breaking through the shell, the chick comes out.

Types of development of chicks. According to the degree of development of chicks hatching from eggs, birds are divided into brood and chicks. In brood birds (black grouse, hazel grouse, chickens, ducks), chicks are born sighted, covered with thick fluff. The mother hen leads them with a brood, warms them with the warmth of her body, gives danger signals, calls them to the found food, etc. In chicks (pigeons, starlings, tits), chicks hatch blind, naked or with sparse fluff.

Parents warm them in the nest with their warmth, bring them food, protect them from enemies.

Seasonal phenomena in the life of birds

Bird nesting. In spring, birds choose nesting sites, build or repair nests, females lay eggs in them, and then incubate them. Most often, birds nest in separate pairs and protect the selected territory from the invasion of individuals of their own and related species. With a limited choice of nesting sites and the ability to forage from a large area, some birds (rooks, sand martins, black-headed gulls) nest in colonies. In some birds, colonial nesting arose as an adaptation for joint defense against enemies.

post-breeding period. The second important seasonal phenomenon in the life of birds is molting. As a rule, it occurs gradually, and the birds do not lose their ability to fly. Only in some (geese, ducks, swans) during molting, all primary feathers fall out at once, and birds cannot fly for several weeks. In the post-nesting period, the birds gather in small flocks and roam in search of food. Some of them (nutcracker, jay) store food for the winter. At the end of summer and autumn, post-breeding migrations intensify and gradually, in some bird species, they turn into autumn and winter migrations, and in others, into autumn migration. According to the development of seasonal movements, birds are divided into sedentary, nomadic and migratory.

Sedentary and nomadic birds. Sedentary birds (house sparrow, jackdaw, rock dove) live in the same area, have adapted to the transition from one type of food to another, the use of human kitchen waste. Magpies, black grouse, capercaillie, hazel grouse, tits are close to sedentary birds.

Nomadic birds (woodpeckers, nuthatches, bullfinches) move away from summer habitats for tens and even thousands of kilometers. They do not have permanent wintering places and repeating routes of movement. By the end of winter, wandering birds usually approach their former nesting sites.

Migratory birds (orioles, swifts, ducks, geese, cranes) fly for wintering and nesting sites along the migration routes that have developed over the centuries. The main signal of the flight is the decrease of the day.

Ways to study bird migrations. Knowledge about wintering areas and flyways of birds was obtained by banding. Recently, miniature sensors attached to the bird's back have been used. Knowledge about bird migration is necessary for their protection and sustainable fishery.

Origin of bird migration. Scientists believe that bird flights arose several hundred millennia ago, when seasons began to set on Earth with climate change in temperate latitudes. The main reason for the occurrence of flights is the lack or absence of food in nesting areas during the cold season.

Origin and major orders of birds

Similarities between modern birds and reptiles. Modern birds and reptiles have a number of similarities: dry skin, scaly cover (in birds on the legs), cloaca, eggs are rich in yolk and have parchment-like or calcareous shells, development without transformation. In modern tropical birds, hoatzins, chicks have fingers with which they cling to tree branches. All this indicates that modern birds and reptiles are related groups of animals and have common ancestors.

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First birds. An important proof of the origin of birds from ancient reptiles is the fossilized imprints of the skeleton and feathers of one of the ancient birds, called the first bird, or Archeopteryx. The first bird was the size of a magpie. Jaws with teeth, a long tail with 20 vertebrae resembled reptiles. Their forelimbs had all the signs of bird wings. The tarsus was developed on the hind limbs, the fingers were located, like in birds, - three fingers forward, and one back. The first birds originated about 180 million years ago from ancient reptiles that ran on the ground on their hind legs, could climb trees, jump from branch to branch.

The most important orders of birds. In the class of birds, about 30 orders have been identified. The largest of them is the detachment of passeriformes. It includes different types of larks, sparrows, swallows, wagtails, starlings, crows, magpies, blackbirds. Passerines are most numerous in forests. The legs of the birds of this order are four-fingered (three fingers point forward and one back). During the nesting period, they live in pairs, building skillful nests. Chicks are born naked, helpless.

Of the other orders of birds, the largest in terms of the number of species are Charadriiformes, Anseriformes, Galliformes, Falconiformes, and Storks. The order of shorebirds includes woodcock, lapwing, plover, carrier and other sandpipers - small and medium-sized birds with long legs and a thin long beak. They live in wetlands, along the banks of rivers and other bodies of water. Sandpipers are brood birds. They feed mainly on invertebrates.

Anseriformes include geese, ducks, and swans. These waterfowl have dense plumage with developed down, a large oil gland, and swimming membranes between the toes. The edges of the wide beak are with teeth or with transverse plates forming a filtering apparatus. Many dive well, getting food from the bottom of the reservoir.

The order of galliformes (grouse, black grouse, capercaillie, quail, partridges, pheasants, wild bank and domestic chickens, turkeys) includes birds with strong legs adapted to raking the soil or forest litter when foraging, short and wide wings, providing a rapid take-off and a short flight. They lead mainly a sedentary or nomadic lifestyle. Galliformes are brood birds. Chicks feed mainly on insects, worms and other invertebrates, adults are mainly herbivorous.

The order of storks (storks, herons, bitterns) combines birds of medium and large sizes with a long neck and long legs. They feed on damp meadows, swamps or in the coastal parts of water bodies with amphibians, small fish, and mollusks. They usually nest in colonies.

The falconiformes order includes falcons, hawks, kites, eagles. They have strong legs with sharp, curved claws, a hooked beak, and sharp eyesight. The wings are either narrow, sharp, contributing to rapid flight, or wide, allowing you to soar in the air in search of prey. The chicks of these birds hatch from eggs sighted, covered with thick fluff.

The group of woodpeckers includes the large and small spotted woodpeckers, the green woodpecker, the black woodpecker (zhelna), and the wryneck. They have a sharp chisel-shaped beak, a long sharp jagged tongue, elastic ends of tail feathers bent towards the support, legs with two fingers pointing forward and two backwards, which allows them to hold well on tree trunks. The exception is the wryneck, which has a straight and weak beak, the tail rods are inelastic. Woodpeckers are nesting birds, hollow-nesting birds.

Ecological groups of birds

The main ecological groups of birds. This or that habitat is inhabited by birds of different orders. In connection with adaptation to life in similar conditions, they developed similar features of structure and behavior, and ecological groups of birds were formed: birds of the forest, birds of marshes, fresh water bodies and their coasts, birds of open desert-steppe spaces, birds of open air spaces, diurnal predators.

Birds of the forest live in spaces bounded by trees and shrubs. In such conditions, they developed adaptations for rapid takeoff and precise landing on branches, maneuvering between trees (shortened wide wings, rather long tail).

Small birds feeding mainly in the crowns of trees and shrubs (tits, kinglets) have thin and sharp beaks, tenacious toes with sharp claws. Woodpeckers and some passerines (pikas and nuthatches) have stiff tail feathers with sharp peaks, a rather strong beak, short legs with tenacious fingers that help to hold onto tree trunks when obtaining food. The birds of the lower tier of the forest (grouse, black grouse, hazel grouse) have developed adaptations for feeding on the ground.

Birds of swamps, coasts and open areas of fresh water. Some of the birds of this group (herons, bitterns, storks) usually feed in swamps, damp meadows, and in the coastal part of reservoirs. They have a long neck, thin long legs. Birds that forage in open areas of water bodies (ducks, teals, geese) have dense plumage, highly developed fluff and subcutaneous fat, a developed oil gland, short legs with swimming membranes, and a wide beak with a filtering apparatus.

Birds of the steppes and deserts (African ostrich, bustard, little bustard) have keen eyesight, a long neck, well-developed legs, allowing them to notice danger in time and hide from enemies. The bustard (males weighing up to 16 kg) and the little bustard (body weight up to 1 kg) living in the steppes of our country are rare birds. The main reasons for this are the plowing of the steppes and poaching.

Birds of open air spaces - swallows (village, urban, coastal), swifts - spend most of their active life in the air. The rapid flight of these birds is facilitated by long narrow wings, strongly developed pectoral muscles, and a notched tail - a rudder during flight. On the fly, they catch insects with a wide-opening mouth.

Diurnal predators (eagles, falcons, hawks, kites) live in various habitats - in forests, mountains, and on the plains. Any diurnal predator can be recognized by a strong hook-shaped beak, powerful legs with strong fingers and curved claws. Among them are scavengers, such as vultures and vultures.

Types of poultry. poultry

The importance of birds in nature and human life. Birds hold back the increase in the number of insects - pests of plants, carriers of pathogens of animals and humans, small rodents. Many of them destroy the seeds of weeds, contribute to the spread of seeds of mountain ash, cedar pine, oak acorns, etc. They and the eggs they lay are included in the food chains of many animals, some reptiles.

Ducks, geese, woodcocks, snipes, great snipes, quails, pheasants as objects of sport hunting, hazel grouses, black grouse, capercaillie and some other birds as objects of trade are of great interest to a person.

Bird protection. In order to preserve the number of birds in our country, strictly defined hunting periods have been established, and the capture of birds during their breeding and molting is prohibited. Places where rare birds are found have become protected areas. In recent years, special attention has been paid to the protection of such rare birds as bustard, little bustard, white crane, white-tailed eagle.

Every person should take care of the birds. The most accessible ways of caring are the manufacture and hanging of artificial nests (hollows, cracks, titmouses), planting hedges of thorny bushes around gardens in which various insectivorous birds nest, feeding birds in winter.

Types of poultry. Man has domesticated a small number of bird species, primarily for the purpose of obtaining meat, eggs, feathers and down. Chickens, ducks, geese, turkeys, and guinea fowls are of the greatest importance in the human economy. The first place among poultry is occupied by chickens. They have tender tasty meat, carry a lot of eggs, they can be kept in a limited area. The ancestor of domestic chickens is the wild Banking chicken. She still lives in the forests of India, Burma and the Malay Archipelago.

Highly organized and capable (with rare exceptions) of flying. Birds are ubiquitous on earth, therefore they play an important role in the formation of many ecosystems, and are also part of the economic activity of people. Modern science knows about 9,000 species of birds that exist today. In different periods of the past, there were much more of them.

The following can be distinguished general for birds characteristics:

Streamlined body shape. The forelimbs are adapted for flight, not walking, therefore they have a special structure and are called wings. Hind limbs of birds serve for walking and as a support for the torso.
The backbone of birds has a small thickness, tubular bones have cavities with air, which lighten the weight of birds and contribute to less weight. This allows the birds to stay in the air longer. Bird skull has no seams, it is formed from fused bones. The spine is not highly mobile - only the cervical region is mobile.
There are two structural features of the skeleton, characteristic only of birds:
- tarsus- a special bone that helps birds to increase the width of their step;
- Keel- a bone protrusion of the sternum of birds, to which the flight muscles are attached.
The skin of birds almost no glands, dry and thin. There is only coccygeal gland, which is located in the tail section. Grow from the skin feathers- these are horn formations that create and maintain a microclimate in birds, and also help to fly.
The muscular system of birds includes many different types of muscles. The largest muscle group is flight chest muscles. These muscles are responsible for lowering the wing, that is, for the flight process itself. The cervical, subclavian, subcutaneous, intercostal and leg muscles are also well developed. Motor activity in birds is differentiated: they can walk, run, jump, swim, climb.
Also exists two types of bird flight: soaring and waving. Most bird species can fly long distances ( bird migration).
Respiratory organs of birds- lungs. Birds double breath- this is when in flight the bird can breathe both at the inlet and at the exhalation, without suffocating in this way. When a bird inhales, air enters not only into the lungs, but also into air bags. From the air sacs, it enters the lungs during exhalation.
The bird's heart four-chamber, capable of completely dividing blood into arterial and venous. The heart beats rapidly, bathing the body in pure arterial blood. High motor intensity is inextricably linked with a high body temperature, which is maintained at a level of about +42 ° C. Birds are already warm-blooded animals with a constant body temperature.
Digestive system of birds has its own characteristics, which are associated with the digestion of large volumes of often coarse food (grains, vegetables, fruits, insects, etc.), as well as with the relief of the mass of the gastrointestinal tract. It is with the latter circumstance that the absence of teeth in birds, the presence of goiter and the muscular section of the stomach, as well as the shortening of the hindgut, are associated. So, birds have no teeth, so the beak and tongue are involved in getting food. goiter in birds served to mix the food entering it, after which it goes to the stomach. AT muscular region of the stomach food is ground and mixed with each other and with gastric juices.
excretory organs in birds, as well as the products of the final breakdown of urea in birds are the same as those in reptiles, with the difference that birds don't have bladders to reduce body weight.
bird brain divided into 5 departments. The largest mass, respectively, the best development, have two hemispheres of the forebrain that have smooth bark. The cerebellum is also well developed, which is associated with the need to have excellent coordination and complex behaviors. Birds navigate in space using sight and hearing.
The birds are dioecious animals, which can already be observed sexual dimorphism. Females have a left ovary. Fertilization takes place inside bird development- direct. Most bird species make nests in which they lay their eggs. The female incubates the eggs throughout the entire time until the chicks hatch, which are then fed and taught to fly. Chicks can be brood and nesting - depending on how well the chicks hatching from eggs are well developed.

Birds are warm-blooded, egg-laying vertebrates adapted for flight.

More than 10,000 species are known in the world, differing 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, only mammals are called animals, which often causes confusion - whether a fish, a frog or a reptile is an animal.

The main signs of birds

These animals have several distinguishing features. Their forelimbs in the process of evolution turned into wings, due to which almost all species are adapted for flight.

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

Bird classification

The class of birds is divided into almost 30 orders, which in turn are divided into families, genera and species. It should also be borne in mind that there is still no clear classification, so different families and orders are often assigned to different groups.

Archeopteryx

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

The whole class is divided into two subclasses:

lizard-tailed (extinct Archeopteryx);
fantails (all others).

Fantails are divided into four superorders:

toothy (also extinct);
floating;
keelless;
ancient palate and new palate.

Floating consist of one detachment - penguins.

The ratites or draenebra are flightless species, these include ostriches, cassowaries, kiwis and tinamoos, five orders in total.

New palatine - this is the largest group, includes more than twenty detachments. Orders usually consist of one to three families, less often five or six, and the most numerous order is passerines, includes 66 families and more than 5000 species, that is, more than half of all known.

Its useful to note: as already mentioned, bird classifications may differ, for example, according to another classification, penguins are considered a superorder of neopalates, and tinamous are not classified as ratites.

Features of the structure and life

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

Like reptiles, they are not viviparous and lay eggs.

At the same time, the ability to fly also affected the structure of their body. Their muscles are stronger, and the total muscle mass is higher in relation to the body than that of reptiles.

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

On the contrary, those of them that live on earth can reach enormous sizes and are distinguished by great weight.

While flying, birds expend a lot of energy, hence the need for a large amount of food and a high metabolic rate. For this reason, their digestion processes have accelerated, and a high body temperature is also characteristic.

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

In addition, it is possible to note individual signs that appeared in different species, depending on their habitat, lifestyle. In non-flying 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 who eat solid food, it is powerful and thick.

The paws of predators are equipped with claws, the floating ones have a membrane formed between the fingers, the woody ones 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 - teaching). 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, as well as systematization and description. Until the 19th century, scientists only dealt with the description of animals, studied 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 areas of science, such as breeding and genetics, and helps agriculture and forestry.

The 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 hand, 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 device of the bird skeleton is directly related to their ability to fly. Bird bones are light, often hollow. The sections of the spine are often fused with each other, except for the cervical, which, on the contrary, is flexible.

The sternum forms a strongly protruding keel, to which strong wing muscles are attached. In non-flying, it, respectively, is absent.

Digestive system

Eaten food passes from the pharynx to the esophagus, from there to the stomach and then to the intestines. Since the 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 excreted.

A well-known feature of bird digestion is its high speed. Some species take a few minutes to completely digest food.

Respiratory system

The structure of the respiratory system of birds is also largely due to their ability to fly, as well as the enhanced gas exchange that their body needs. The respiratory system in birds is distinguished by a complex structure, in comparison with similar ones in 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 in flight, it enters the air sacs, and when exhaling, due to the special structure of the lungs, it re-passes through them.

circulatory system

The avian circulatory system is closed and has two circles.

The bird's heart is four-chambered and its heart rate is very high, especially during flights. The lymphatic system is underdeveloped.

excretory system

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

From each kidney leaves the ureter, which opens into the middle part of the cloaca. The adrenal glands are located near the upper edge of the kidneys. There is no bladder, as is the case with the rectum, this allows urine not to linger in the body and lightens 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 ones.

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

On the contrary, the olfactory lobes are small, and therefore most of them do not distinguish smells well (with the exception of scavengers). The intelligence of many species is quite high, they can use improvised items, they are capable of learning.

reproduction

In birds, sexual dimorphism is pronounced (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. A high temperature is necessary for the development and subsequent hatching of the chick, so one of the parents (or both in turn) hatch it.

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

Fertilization

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

During mating, the male simply presses his cloaca against the female (this is where the genital tract exits) and throws the seed into her. In the future, it enters the ovaries and there it fertilizes the already ripened eggs.

Conclusion

Birds play a huge role in the life of the ecosystem. Carnivores and insectivores contribute to the regulation of the number of other animals, at the same time, many birds themselves eat other vertebrates. Also, those of the birds who feed on the fruits of plants contribute to the spread of their seeds.

Birds also play a huge role in people's lives, from food, household and ending with culture and art. A number of birds occupies 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, one 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 people, not counting hundreds more that are on the verge of extinction. Only relatively recently endangered species came under protection, and even attempts are being made to bring back to life the already extinct ones.