Contour feathers form on a bird. What is down and feather? Feathers don't grow there

Feathers distinguish birds from all other creatures living on our planet. Feathers come from the scales that cover reptiles. Birds need plumage for flight, to keep warm, and to attract the opposite sex. Different species of birds differ from each other in the color and shape of their feathers, and in some cases, thanks to their plumage, it is possible to distinguish a male from a female.

The feather is made of keratin- a protein that forms our nails and hair. Each feather has a central shaft, the base of which, the hollow rim, is covered by a feather bag located in the skin.

Feathers with second-order barbs are called contour feathers, while feathers without them are called down feathers. Some feathers consist of both a contour and a down part.

Feathers do not completely cover the bird's body. The feathered areas are called pterilia, and the areas without feathers are called apteria.

Types of feathers

Birds have different types of feathers, each serving a specific function.
Outline feathers. Contour feathers cover most of the bird's body, giving it a streamlined shape. They protect the bird from sun, wind, rain and wounds. Often these feathers are brightly colored. Contour feathers are divided into flight feathers and coverts.

Flight feathers. These include feathers on the wings and tail.
The flight feathers of the wings can be divided into three groups:
First-order flight feathers are attached to the hand and create thrust during flight. There are usually 10 primary flight feathers, which are numbered starting from the inside of the wing.
Secondary flight feathers are attached to the forearm and are necessary for the bird to rise into the air. They are also used in the courtship process. There are usually 10-14 secondary flight feathers and they are numbered from the outside of the wing inwards.
The flight feathers located closest to the bird's body are sometimes called tertiary.
Tail feathers, called tail feathers, help the bird navigate in flight. Most birds have 12 tail feathers

The flight feathers are covered with smaller contour or integumentary feathers. The wing has several layers of outer feathers. The cover feathers also cover the bird's ears.

Some birds (herons, some nightjars, bustards, parrots) have a special type of down feathers - powder feathers, areas with constantly growing down, the tips of which easily break off, forming a fine powder - “powder”. They are usually located on the sides of the chest or on the lower back. With its claws, the bird spreads the “powder” throughout the entire plumage, which presumably increases the water-repellent properties of the plumage. This powder also helps the bird clean its feathers. Its absence in cockatoos or African gray parrots may indicate diseases of the beak and feathers.

filament feathers. These are very thin, thread-like feathers with a long shaft and several barbs at the end. They are located throughout the pterilium. It is not entirely clear what their function is, it is believed that they relate to sensory organs, perhaps helping to establish the position of the flight feathers in accordance with air pressure.

Down feathers. Down feathers provide shape, aerodynamic properties, and thermal insulation. They also play a role in the courtship process. They have a thick trunk, but a small fan. They can be found among the integumentary feathers or in certain areas of the pterilium.

Bristles. The bristles have a soft shaft and several barbules at the base. They are usually located on the head (around the eyelids, mouth, nostrils). They perform both sensitive and protective functions.

Feather growth

Like hair, feathers develop in a special area of ​​the skin called a follicle. When a new feather develops, it has an artery and vein in the shaft that feed the feather. The feather at this stage is called "blood". Due to the color of the blood, the stem of the blood feather is dark, while the adult feather has a white shaft. A blood feather has more wings than an adult. The blood feather grows from a waxy keratin sheath that protects it during growth. As the feather matures, the blood supply stops and the waxy protection is removed by the bird.

Although an adult bird usually sheds all its feathers during a moult, the loss of feathers is usually spread out over several months, leaving enough for flight and insulation.

Shedding is usually caused by a change in day length and can occur after the mating season. Some wild birds, such as goldfinches, molt twice a year, exchanging their bright “wedding” attire for a more modest one.

The color of a bird's feathers is determined by the presence of various pigments, such as melanins, carotenoids, and porphyrins.

Melanins are brown and black pigments that are also found in mammals. In addition to affecting the color of the feather, they also help the feathers to be denser and resist wear and tear from sunlight.

Carotenoids are yellow, orange and red pigments. They are synthesized by plants and absorbed by the bird's digestive system, and then enter the follicle cells when the feather develops.

Porphyrins are red and green pigments that are produced in poultry follicle cells.

The next time you see a bird, you will understand how feathers enable it to fly and how they protect it, and you will be able to appreciate the complexity and uniqueness of these representatives of the animal kingdom.

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"A bird is recognized by its feathers." This folk wisdom reflects the scientific fact that a feather is a unique formation found only in one class of animals. In fact, no existing group of living organisms except birds have feathers, and there is no evidence that any extinct group had them.

The role of plumage in the life of birds is difficult to underestimate. It is the feathers, creating the load-bearing surface of the wing and the streamlined shape of the body, that allow birds to fly. Feather is an excellent heat-insulating and water-protective material, and different colors and features of the shape of the plumage carry information about the species and sex of the bird, thereby playing an important role in intraspecific and interspecific communication.

Bird feathers originate from the scales of reptiles and also consist of horny substance. They, like the scales of reptiles, are derived mainly from the superficial, epithelial layer of the skin (epidermis), and consist of dead and highly modified cells.

Lots of feathers - good and different

Based on their structure, feathers are divided into several types: contour, down, filamentous, down and bristles.

I, II – contour feathers; III – down feather; IV – fluff; V – thread-like feather; VI – seta; VII – diagram of the structure of a contour feather under high magnification.
1 – origin, 2 – inner part of the fan, 3 – outer part of the fan, 4 – downy part of the feather’s fan, 5 – shaft, 6 – side (additional) shaft, 7 – upper navel of the feather, 8 – lower navel of the feather, 9 – barbs of the first order, 10 – barbs of the second order, 11 – hooks

Outline feathers, apparently, are the most familiar to the reader (Fig. 1, I, II). They cover the entire body of the bird, form the wings and tail and create a characteristic “bird” appearance. Externally, the contour pen is divided into those located in the axial part kernel And fan(Fig. 1). The lower, free part of the rod is called at the start. It has an internal cavity that is filled with spongy tissue. At the lower end of the edge, the cavity opens with a small hole - lower navel feather, and at its upper end on the border with the fan there is, accordingly, upper navel(Fig. 1, 7, 8 ). The rod in the area of ​​the web is more dense in structure, does not have an internal cavity, and its core is formed by keratinized cells filled with air. The fan itself is formed by small “branches” extending in both directions from the rod - beards of the first order(Fig. 1, VII, 9 ). They are so tightly interlocked that they give the impression of a continuous surface. But if you look closely, or even better, put a contour pen under the binocular, you can see that from each first-order barb, smaller barbs extend in rows on both sides, called beards of the second order, or beards(Fig. 1, 6 ). If we examine this area under even greater magnification, then on each second-order beard a number of small hooks will be revealed. It is with their help that neighboring barbules are linked to each other, resulting in the formation of a continuous plate (Fig. 1, VII).

Structure down feather similar to the structure of the contour one, with the only difference being that the barbules on the down feathers are soft, devoid of hooks, and therefore the barbules of the first order are not interlocked with each other. There is an assumption that feathers with unlinked barbs are more primitive than contour feathers, and as indirect confirmation we can cite the fact that ratites (a fairly ancient group that includes African ostriches, cassowaries, rheas and kiwis) do not have feathers with linked barbs at all .

Pooh differs from a down feather in the absence of a shaft - its barbs, also uncoupled, extend immediately from the feather.

Thanks to this structure of the barbs, the feathers of these two types play the role of a “fur coat”, holding a stationary layer of air near the skin. For many groups of birds (for example, chickens, owls, pigeons), the additional(side) kernel, which extends from the edge of the contour or down feather. It is always much shorter and thinner than the main one and bears soft beards, like on a down feather. Loose barbs are often present in the lower part of the blade of contour feathers, which also increases body insulation. In general, between contour and down feathers, all intermediate stages are possible.

Interestingly, temperate species have a higher proportion of down feathers and down in their plumage than tropical species. If a bird has winter and summer plumage (for example, many grouse), then the number of unlinked “downy” barbs in the winter plumage increases, sometimes occupying almost the entire fan. In this case, the “additional feathers” are better developed in winter. In winter, even the number of feathers in sedentary birds of the middle zone increases - mainly due to down, which “sprouts” by winter.

filament feathers And bristles have the simplest structure and consist only of a rod, thin and soft for thread-like feathers and hard and elastic for bristles. The fan is reduced, and only a few barbs remain at the end of the filamentous feathers. Thread-like feathers serve for touch (react to the movement of air currents) and grow throughout the bird’s body. The bristles can be found in many species at the base of the beak, where they also perform a tactile function, and in nightjars, swifts, flycatchers and other birds that grab prey in flight, they help “enlarge” the mouth section. In many birds, bristles grow along the edges of the eyelids, forming eyelashes.

Some groups of birds (herons, some nightjars, bustards, parrots) have powders– areas with constantly growing fluff, the tops of which easily break off, forming a fine powder – “powder”. They are usually located on the sides of the chest or on the lower back. With its claws, the bird spreads the “powder” throughout the entire plumage, which presumably increases the water-repellent properties of the plumage.

The life path of a pen - childhood, adolescence, youth

The skin of vertebrates consists of two layers of different structure and origin: epidermis And dermis(aka cutis, corium, skin itself). The epidermis is located on the surface and belongs to epithelial tissues, the dermis - to connective tissues. Accordingly, in its origin, the epidermis is a derivative of the ectoderm of the embryo, and the dermis is a derivative of the mesoderm. The epidermis of vertebrates is multilayered, the cells of the outer layers are gradually filled with horny substance, die and slough off, while the epidermis is constantly renewed due to the constant division of its lowest layers of cells (the so-called germinal layer). The main function of the epidermis is protective; it is also the ancestor of a number of skin formations in vertebrates (in addition to feathers, these are claws, mammalian hair, deer antlers) and skin glands (sebaceous, sweat, mammary). The dermis is rich in blood and lymphatic vessels and provides nutrition to epithelial tissue, growth and development of its derivatives.

A – feather papilla stage; B – tube stage (barbs develop inside the cap); B – stage of cap rupture. 1 – epidermis, 2 – dermis, 3 – feather barbs, 4 – sheath, 5 – feather cavity, 6 – feather bag

As a result of cell proliferation epidermis And dermis a tubercle is formed on the skin, similar to the rudiment of the scales of reptiles, which gradually grows in the form of a backward-directed outgrowth, and its base gradually deepens into the skin, subsequently forming a feather bag. The outgrowth is covered with epidermis on top; underneath there are living tissues of the dermal layer, rich in small blood vessels, which form the feather papilla (Fig. 2, A). As they grow, they stretch the feather outgrowth in length, the epidermal layer gradually becomes keratinized, and the outgrowth itself takes on the shape of a tube. At the outer end of the feather tube, the epidermis is stratified: its outer thin layer is separated in the form of a conical cap, and the feather barbs are further differentiated from the inner layer of the epidermis. In the case of the development of a contour feather, a series of parallel horny ridges are first formed, one of which, the thickest, subsequently becomes a shaft, the rest, as they develop, move onto it (Fig. 3), turning into first-order barbules, on which second-order barbules develop. During the development of down, no shaft is formed, and all parallel ridges subsequently become downy barbs of the first order. All feather development occurs inside the sheath.

a – germ layer; b – cover; 1, 2, etc. – serial numbers of epidermal folds – future beards of the first order

As the feather grows, the living feeding cells of the papilla die off, starting from the end of the feather tube, the cap at its end breaks, and the feather barbs come out, forming a kind of feather tassel. Usually, after the sheath ruptures, feather growth continues at the base, and the young feather at this stage is much shorter than it should be. It reaches its final length when the fan is completely freed from the cover, the remnants of which in the form of thin films remain for several days at the base of the fan.

The feather is held in the skin by tightly fitting walls of the feather bag and muscle bands that ensure its mobility.

Feathers don't grow there...

Speaking about feathers, of course, it is necessary to point out that in most birds, contour feathers do not grow in a continuous layer over the entire surface of the body, but only in separate areas, which are called pterilia(from Greek pteron– pen and hyle- forest).
Areas that do not bear feathers are, on the contrary, called apteria.

Down feathers grow along with contour feathers on the pterilia. Down can either relatively evenly cover the entire body of the bird (in copepods, anseriformes, many diurnal predators, etc.), or be only on the apteria (herons, owls, many passerines). Less commonly, it grows only together with the contour plumage on the pterilia (tinamou). Only a few representatives of the class have a body evenly covered with feathers, without apteria: penguins, palamedea and birds of the ratite group.

The presence of apteria allows the bird not only to “save” on plumage (the body is covered with fewer feathers). Paradoxically, birds with apteria have better thermoregulation. Surely everyone has seen a ruffled crow or jackdaw sitting on a branch in winter, or watched a budgerigar fall asleep in a cage - their feathers rise, puff up in all directions, and the bird resembles a fluffy ball. It is the presence of apteria that gives more opportunities for feather mobility, due to which the looseness of the plumage and the thickness of the air cushion increase, and this, in turn, helps to retain heat.

Rice. 4. Layout of the main pterilia on the bird’s body:
1 - cephalic pterilium, 1a - auricular region, 2 - flight feathers, 3 - wing pterilium, 4 - brachial pterilium, 5 - dorsal pterilium, 5a - cervical region, 5b - dorsal region, 5c - sacral region, 6 - femoral pterilium, 7 – tibia (leg) pterilium, 8 – abdominal pterilium, 8a – thoracic region, 8b – ventral region, 9 – caudal pterilium, 10 – tail feathers

Despite the fact that the location and shape of the pterilia vary somewhat and may even be a systematic feature, the location of the main pterilia on the body of birds is similar (Fig. 4). They are quite easily identified when examining a bird - these are the dorsal, thoracic, humeral, femoral, and cervical pterilia. Of the smaller pterilia, even a novice naturalist can easily find the auricular and anal pterilia. In addition to the ears, a fairly large number of small pterylia can be distinguished on the heads of birds, which can only be understood by narrow specialists in matters of morphology and molting. And since the majority of readers are not them, we will limit ourselves to the general name of all pterilia of this part of the body (by the way, very often used) - cephalic pterilium.

Tail and wings

The plumage of the wings and tail is worth talking about separately. The large feathers that form the tail itself are called helmsmen. They differ in that their outer and inner webs are more or less the same width. The feathers covering the tail feathers above and below are called, respectively, top And lower tail coverts.

The number of helmsmen varies in different detachments. Most often there are 12 of them, but there can be from 8 to 28 (in some waders), in the passerines of our fauna - 12 (hereinafter this order will be discussed separately, since it includes about half of the species of domestic avifauna). The numbering of the tail feathers is taken from the edge of the tail to the center (in the same direction they are replaced during molting in passerines).

Unlike tail feathers, the feathers that form the load-bearing plane of the wing, called flywheels, are clearly asymmetrical: the outer edge of their web is much narrower than the inner one, while in flight feathers there is often a noticeable notch on the outer web. Distinguish paramount(they are attached to the back surface of the skeleton of the hand), minor(attached to the ulna) and tertiary(attached to the humerus and are usually located one above the other on the wing) flight feathers. Also, these feathers can be distinguished from tail feathers by a certain concavity, which provides the wing with better aerodynamic qualities in flight. In addition to the flight feathers on the wing there are wing- several feathers attached to the single phalanx of the first finger, which prevent the occurrence of air turbulence during flight (Fig. 5).

Rice. 5. Wing feathers - top view (using the example of a representative of the passerine order).
I – flywheels: 1–10 – primary, 11–16 – secondary, 17–19 – tertiary; II – wing; III – coverts of primary flight feathers; IV – large upper coverts of the secondaries; V – middle upper coverts of the secondary flight feathers; VI – small upper coverts of the secondary flight feathers; VII – shoulder coverts

There are usually 9–11 primaries; in the passerines of our fauna there are 10. The number of secondary ones varies in different groups from 6 (hummingbirds, passerines) to 40 (large albatrosses). The number of tertiary flight feathers is also very different; passerines usually have 3, with the exception of the families Orioles (4), Corvids (4–6). The numbering of the flight feathers is taken from the outer (distal, scientifically speaking) edge of the wing towards the body. It can be either continuous - in this case, separate groups of primary, secondary and tertiary flight feathers are not distinguished, or, if the boundary between the primary and secondary ones is easily distinguishable (for example, among representatives of the order Passeriformes), each group can be considered separately, again starting from the distal end. That is, if you want to indicate the coordinates of the fallen flight feather of your favorite finch (the thirteenth in a row from the edge of the wing), you can simply write it down as the 13th flight feather or as the 3rd secondary flight feather. The task is somewhat complicated by the fact that in all birds the first primary flight wave is shorter than the others, and in many groups it is greatly reduced, sometimes going almost to nothing (for example, in larks, swallows, wagtails, buntings, etc.), and you can simply not notice it . Therefore, ornithologists agreed to count from the first full-fledged flight feather, counting it as the second.

Like the tail, the wing has upper and lower coverts. Above the secondary flight feathers, the upper coverts usually form 3 distinguishable rows: the first row above the flight feathers is the large upper coverts of the secondary flight feathers, above them are the middle ones and then the small ones. Behind the lesser coverts there are small feathers, collectively called propatagium coverts, or, more simply, shoulder coverts.

As for the undercovers, separate groups are usually not distinguished among them, sometimes classified according to the flight feathers that they cover.

Feather: beauty secrets

All the variety of colors, the amazing richness and grace of the shades of birds' plumage is created by pigments of two groups and some features of the feather structure. Accumulating in horn cells in the form of lumps and grains melanins give the feather shades of black, brown, reddish-brown and yellow. Lipochromes lie there in the form of fat drops or flakes and provide brightness of color: red (zooerythrin, phasianoerythrin), yellow (zooxanthine), blue (ptilopine) and other colors. The combined occurrence of several pigments on one area of ​​the pen significantly expands the range of shades shown here. In addition to imparting color, pigments, especially melanins, increase the mechanical strength of feathers.

Apparently, this is precisely what explains the predominantly black or brown coloring of at least part of the flight feathers of most birds, even those whose primary plumage color is white (white stork, white goose, many gulls, etc.). An interesting exception here are species with “reverse” coloration, black with white flight feathers - the black swan, two species of saddle-billed storks, and the horned raven from the hornbill family.

The white color of the plumage is due to the presence in the horny cells of the feather of transparent cavities filled with air, in the complete absence of pigments. If the cell walls are not transparent enough, the feather acquires a bluish or bluish tint. The metallic sheen of plumage, characteristic of many birds, is formed due to the decomposition of light into a spectrum on the surface of the feather, where the outer keratinized cells are a kind of prisms.

By all these methods listed above, the color of a feather is formed; all that remains is to add that this happens only during its development, and changing the color of a feather during life is impossible (except for the fact that under the influence of natural factors the pigments are destroyed, and over time the feathers fade somewhat ).

Time to scatter feathers...

It should be remembered that in poultry, molting can occur at any time of the year. For wild birds, the annual molt is usually confined to a specific season; only in some tropical species it can occur gradually throughout the year. The characteristics of molting vary in different groups of birds; this topic is extensive and deserves a separate discussion. Here we think it is necessary to point out that during the molting process there is an age-related and, for many species, a seasonal change in feather outfits. Thus, the same bird can have completely different plumage throughout its life. Accordingly, several main feather patterns of birds are distinguished.

Embryonic outfit– is formed during the period of embryogenesis and varies in the degree of development in different orders, usually better developed in chicks with the brood type of development. It may consist of embryonic down and embryonic feathers (the latter can be found on the chicks of Anseriformes, Galliformes, Tinamou, as well as ostriches and the like). Completely absent in swifts, woodpeckers, coryciformes, and pelicans.

Nesting outfit(adolescent, juvenile) - replaces the embryonic one (if present), while part of it is replaced by embryonic down and feathers, and part is formed in new feather papillae. The nesting plumage can be worn by different species for varying periods of time - from several weeks to a year, and usually differs from the plumage of an adult bird in color and plumage structure. In a number of species, the differences in color are insignificant, and the young are simply dressed more dullly, without the characteristic shine (ravens, some tits, kingfishers, pigeons, many rails, etc.).

For other groups this difference is more noticeable. For example, in most representatives of the thrush family, which are very diverse in color, the young are quite similar - variegated due to bright light spots along the shaft and brown edges of the feathers. The chicks of gulls and light terns are motley, brownish-brownish. The chicks of white swans are brownish-gray, the chicks of the white crane are reddish-brown, etc. – there are many examples that can be given.

Quite often the juvenile plumage is variegated due to light buffy spots on the feathers. This type of coloration is considered evolutionarily more ancient for birds. In the presence of sexual dimorphism, it is similar to the coloration of females (Culiformes, ducks, turukhtana, many passerines). It may simply be more faded - with a pronounced change in seasonal color, it resembles the winter attire of adult birds (loons, grebes, many waders and auks, etc.). But even in those birds in which the young are almost identical in color to the adults (warblers, some warblers and tits and a number of other species), the feathers of the nesting plumage are always somewhat different in structure from the feathers of adult birds: they have barbs of the first and second order are less often and weaker linked to each other, the plumage gives the impression of being looser and softer.

Interestingly, young guillemots and auks have two generations of juvenile plumage. The first generation of feathers gives way to embryonic down by the 20th day of life: these feathers are much shorter than the feathers of an adult bird and more loose. In this plumage, young guillemots and auks go to sea and there, by the age of 2 months, they molt into the final form of juvenile plumage, close to the plumage of adults. All other representatives of auks have only one juvenile plumage and put it on at the age of 1–1.5 months, at which time they leave the nests.

Often isolated post-nesting plumage, which replaces the nesting one during the post-nesting molt. It usually occurs in the first autumn of life before seasonal migrations, less often it extends and ends already in wintering grounds. Usually this molting does not affect the flight feathers, and sometimes even the tail feathers. Often, the post-nesting plumage is practically indistinguishable from the adult plumage in color and structure, however, in some large birds (swans, gulls, diurnal raptors, etc.), the final coloring is acquired only in the 2nd or even 5th year of life. In this case, they talk about the first annual outfit, the second annual outfit, etc.

Annual outfit(intermarital) – is formed in adult birds after postnuptial (autumn) molt. Most often, it begins after the completion of nesting and the flight of the last chicks and ends before the start of autumn migration, but there are also numerous deviations from this pattern. Thus, in some species, usually of a fairly large size, it begins simultaneously with the laying of eggs (hawks, wood pigeons, snowy owls, some corvids), others molt already during the wintering grounds after autumn migration, or part of the plumage changes before migration, and part - after and etc.

The example of hornbills is widely known, when the male molts “as expected,” and the female does this during the incubation period, while her husband walls her up in a hollow, leaving only a narrow hole for feeding.

The annual plumage is worn until the next autumn molt (if the species does not have a nuptial molt, which will be discussed below). The autumn molt is almost always complete, with the exception of some large birds (herons, storks, eagles, etc.), in which all the flight feathers do not have time to change during the molt and some of them change once every two years. Cranes always molt their flight feathers every other year.

IN wedding attire birds usually molt before the breeding season in late winter–early spring, although there are exceptions (ducks begin to dress in breeding feathers in August and finish in winter). The molt can be complete, but more often it is partial, when all the small contour feathers change or only part of it, but the flight feathers and tail feathers are preserved. Molting occurs in both sexes, and the color of males may change, while that of females usually remains the same.

In some birds, the change in color for the mating season is not due to molting, but to wear and tear of the plumage. In spring, the male House Sparrow has a striking black chin, throat and upper chest, although in autumn these areas were almost the same grayish-brown color as the surrounding plumage. In this case, the feather has a black middle part of the fan with light edges to match the rest of the plumage, and since the feathers overlap each other in a tiled manner, the black color is invisible. Over the course of the year, the weakly pigmented (and therefore less durable) edges of the feathers are gradually worn away, and by spring (i.e., by the beginning of the mating season), male house sparrows acquire a characteristic color. In the same way, the common starling, variegated in the fall, turns out to be a solid black color with a metallic sheen in the spring. The red color “appears” in the breeding season on male redstarts, redpolls, linnets, etc.

Although both people and potential sexual partners are primarily attracted to a bird by its plumage, the primary purpose of feathers is not attractiveness. Feathers serve as a protective covering and play an important role in flight. The protective function is probably more significant. Some birds, such as ostriches and penguins, get along just fine without the ability to fly. Durable and light feathers retain a layer of air heated by the body against the skin and act as a heat insulator so effectively that with enough food, birds are able to survive in very severe cold weather.

The fly feather is something of an engineering marvel. From the rigid but elastic central rod, side plates called first-order beards extend in both directions at an angle. Each beard consists in turn of a central rod with even smaller second-order beards. These latter have a complex system of hooks and notches, with the help of which each second-order beard is linked with similar elements on the adjacent first-order beard, so that the feather blade is a solid, fairly dense plate. If the feather is frayed, the bird passes it through its beak, and it returns to its original appearance.

The feathers on the wings of birds are called flight feathers, and the feathers on the tail are called tail feathers. Covert feathers are very similar to flight feathers and tail feathers, except that hooks for “fastening” are often present only at the end of the feather, and the rest of the feather is loose and fluffy.

The third type of feathers, called filamentous, are small, they do not have a real fan, there are only small tufts of flexible barbs at the tip of the shaft. Feathers of the fourth type have a short soft shaft with long and soft barbs without hooks. Down provides additional thermal insulation. In chicks, the feather cover is down. Many adult birds also have it.

Feather cleaning

When we talk about a person: “preening his feathers,” we mean that he is preening. However, birds simply need this to keep their feathers in good condition. First, the bird rubs its beak against the sebaceous gland at the base of its tail and smears the fat on any tuft of feathers, and then runs its beak over them, pinching. This procedure, in addition to removing dirt, straightens crumpled beards and “fastens” loose hooks. The bird pays special attention to the flight and tail feathers. Some birds, in particular herons, in addition to the coccygeal sebaceous gland, have a special down - powder down, or powders, which, as they grow, turn into a powder that covers the feathers like powder.

Bird feather color

In zoos, it happens that flamingos look healthy, but do not have the wonderful pink color, remaining just white. The reason for this is nutrition. When captive birds are fed shrimp, they regain their vibrant colors. The fact is that the reddish color of flamingo feathers, yellow in canaries, as well as in almost all birds with red, yellow or orange plumage is due to natural pigments - carotenoids, which are included in the composition of the feather as it grows. Black and brown shades are produced by the pigment melanin (humans have it in their skin and hair). Pleasant blue shades are due to light scattering, not pigments. Green is obtained when a layer of yellow pigment lies on top of an area that is blue.

Bird plumage

The plumage of every bird is unique. The species can often be identified by a single feather. Some species have completely unusual and specialized plumage. For example, the dazzling tails of peacocks and lyrebirds are used for display. Some insectivorous birds have bristles around their mouths. In herons, some parts of the body are covered with powder.

Penguins have a body covered with feathers more or less evenly. But in most birds, feathers tend to grow in certain areas (pterylia) and between them there are areas of bare skin (apteria). This is clearly visible on a plucked chicken: where there were feathers, small pimples (feather follicles) remain, while areas without feathers are smooth.

Areas of bare skin are usually covered with feathers growing nearby. However, many vultures have hairless heads and sometimes necks. It is believed that this is due to the manner of carrion birds sticking their heads inside the carcass while eating. The American bald eagle is also a scavenger, but not bald - the feathers on the head of this bird are brilliant white, like the hair of a wise old man.

Birds molt

No matter how strong and elastic the feathers are, over time they wear out and periodically fall out, being replaced by new ones. Typically, only a small number of feathers fall out at a time. A notable exception are ducks and other waterfowl, which are so massive that they would not be able to fly normally without having all their flight feathers on their wings. These birds shed and replace all their flight and tail feathers at one time, waiting out the summer molting period in a secluded place. The growth of new feathers requires energy, so molting should not coincide with a large expenditure of effort, for example during the breeding season or migrations. Usually shedding occurs once a year. Birds that make long migrations molt twice a year. The same thing happens with birds that live in thorny bushes or any other places where feathers wear out quickly.

A herring gull that has just hatched from an egg is covered with down of a protective color - gray with black spots. When the flight and tail feathers grow, the bird turns dark brown. With subsequent molts, it lightens until it acquires a shiny light gray and white plumage. characteristic of adults.

In many species, chicks differ in appearance from their parents. But adult birds do not always look the same. The tundra partridge is white in winter, which corresponds to its snowy habitat; by summer it becomes variegated brown, merging in color with stones and vegetation. Males sporting colorful breeding plumage shed their eye-catching feathers towards the end of the mating season. The male red-and-black piranga, for example, changes its spring red plumage to dull green. The color can change without molting - the feathers fade in the sun, their tips wear off. The pelican's neck feathers turn yellow, absorbing oil from the sebaceous glands. For the same reason, the gull's plumage turns pink.

The bird's body has feathers and downy covering. However, in most birds, feathers do not grow over the entire surface, but in certain areas. They usually run along the body (in the direction of flight) in different species of birds in different ways and have names in accordance with the part of the body on which they are located: head, cervical, wing, shoulder, lateral, thoracic, dorso-lumbar, abdominal, femoral , shins, caudal, anal, etc.

Areas of the body free from plumage are apteria. They are also named based on topographical characteristics. At the same time, the feathers are arranged in such a way that they cover the apteria, forming a continuous feather cover. In flightless birds (ostrich, penguin), feathers grow over the entire surface of the body.

The purpose of the feather cover is to protect the body from mechanical stress and is one of the devices that ensures the maintenance of body temperature. Feather plays an important role in the regulation of heat exchange (while the chicken is covered with down, the difference between the temperature of the skin and air is 13-15°C, with the appearance of feathers it reaches 17-19°C). The plumage increases thermal insulation and creates a layer of still air around the body, which prevents heat transfer. By changing the angle of the feathers, the bird can regulate heat transfer.

In addition to its thermoregulatory function, the feather cover creates a streamlined body shape that facilitates flight, and creates load-bearing surfaces that make flight possible.

Feathers, depending on their shape and function, are divided into:

• ? contour,
• ? downy,
• ? semi-down,
• ? filamentous,
• ? tassel,
• ? bristles,
• ? powder fluff (powdery).

Outline feathers - the most common type of feathers. They determine the outline of the bird's body. Among them are:

• ? coverts,
• ? flight feathers,
• ? tail feathers.

Covert feathers located on the head and cervical pterilia. From the lateral, thoracic, sternal and ventral pterilia the covering feathers of the thoracic region of the body, flank (tip of the sacrum) and abdomen extend. The covert feathers of the dorsal-lumbar and caudal pterilia form the plumage of the lower back and the covert feathers of the tail; in roosters they form large and small braids. The shin coverts form the trousers.

A mature covert feather consists of a trunk, a shaft and a fan (Fig. 4). The lower part of the trunk (before the fan) is cylindrical in shape and is called the stem (calamus). The lower part of the ostrich is enclosed in a feather pouch and immersed in the skin. At the end of the eye there is a depression with a hole - the lower navel. In this recess is the rudiment of the next generation of feathers. The walls of the ochin consist of a rather transparent horny substance. In a young contour feather, most of the quill is filled with a connective tissue papilla with a rich vascular network, which gives it a red or blue color. As the papilla matures, it shortens, the edge fills with air, and the keratinized cells of the epidermis, remaining in their original places, turn into funnel-shaped films, as if marking the stages of reduction of the papilla, at the level of the web, gradually narrowing, the edge turns into a tetrahedral rod. At the transition point there is a depression - the upper navel. An additional feather begins from it.

Rays (barbs) of the first order extend from the rod in both directions at a certain angle, collectively forming a fan - an elastic feather plate. the lowest small part of the fan is called silky, the middle one is downy, the upper one is contour. The outer half of the covert feather's web is narrower and tighter, the inner half is wider and softer. From the rays of the first order, numerous rays (barbs) of the second order extend symmetrically at an angle in both directions, and on one side they are located slightly higher than on the other. The underlying beards of the second order have a ridge curved in the form of a cornice running along the upper edge of the ray.

The overlying rays of the second order bear rays (barbs) of the third order, which are outgrowths of keratinized epithelial cells in the form of cilia and hooks. The hooks extend beyond the ridges of the second-order rays of the adjacent feather, along which they can slide, maintaining an elastic connection with each other. The structure of the hooks and their number are species specific. the cilia create a roughness that prevents the feathers from sliding over each other, increasing friction, which helps keep the feathers in the form of a continuous cover.

The silky part of the covert feather's fan is characterized by a rudimentary state of second-order rays. In the downy part, cilia and hooks (third-order rays) are undeveloped.

The rod and rays of the first order are formed by three layers of cells.

The outermost one - the cuticle - consists of one row of squamous keratinizing epithelium.

The middle layer - the cortex - is formed by a large number of rows of elongated and flattened keratinized epithelial cells, tightly adjacent to each other, which ensures the strength of the feather. The inner layer - the medulla - consists of multinucleated large keratinized cells filled with air, which gives the feather greater lightness. In the origin and rays of the second and third orders, the medulla is not expressed. The shape of cells and layers is species specific.

Rice. 6 .

1 - rod, 2 - fan, 3 - feather, 4 - rays of the first order, 5 - rays of the second order, 6 - hooks, A - flight feather, B - section of the fan.

Covert feathers are movable. This is ensured by well-developed smooth muscles that entwine the feather follicle and end in the dermis. In this case, each covert feather turns out to be naturally connected with four neighboring feathers. This connection allows the body coverts and follicle muscles to be raised and lowered synchronously. The areas of skin adjacent to them are abundantly innervated by both free nerve endings and Herbst bodies.

Flight and tail feathers arranged similarly to coverts. Unlike the latter, they have longer feathers, less developed silky and downy parts of the fan, and a longer covering part of the fan.

Down feathers, or fluff- small, have a short spine, an underdeveloped shaft and a fan with unconnected rays due to the absence of hooks and cilia. The rod may not be developed, in which case the rays extend directly from the origin. down is located on the pterilium between the contour feathers, but can also grow on the apteria, especially in the area of ​​the flank and belly. The main function is thermal insulation, warming the bird's body. The fluff of waterfowl is most developed.

Semi-down feathers- have the same structure as down, but their shaft is always developed. Feathers of this type are common in the flap and belly areas.

filament feathers- have a long, very thin rod, at the top of which there is a small fan, consisting of only a few connected rays. They are located in numbers of 1-8, always near the contour feather, covered by it and apparently develop from the same papilla. The turkey grows on its chest in the form of a bunch.

Numerous nerve endings were found in the bags of filamentous feathers. It is believed that they have a receptor function; with their help, the bird senses a disorder in the contour feather and eliminates it. Perhaps they provide the signaling necessary to control the movement of the plumage. In this case, it is obvious that the reflex arc closes on the muscles of the contour feather.

Tassel feathers have a thin trunk and loosely linked rays, diverging like the hairs of a brush, located around the duct of the coccygeal gland.

Bristles- short feathers consisting of a small trunk without a fan. They are found at the base of the beak, near the nostrils and eyes.

Powder fluff(crumbly, powdery) is well developed in birds in which the coccygeal gland is absent or poorly developed (pigeons, herons, etc.)

Feathers are not only a decoration for birds. They provide warmth, the ability to fly, find a mate during the mating season, hatch offspring and hide from predators. Let's look at the types of feathers and their structure.

For what

Plumage is a feature unique to the class of birds. It is vital for birds and performs many functions. It is feathers that allow birds to fly, creating a streamlined body shape, and most importantly, the load-bearing surface of the wing and tail. The feather protects the animal's body from damage and injury. The waterproof function is effective - the tops of the feathers fit tightly to each other and prevent getting wet. The lower part of the contour feathers, down feathers and down are closely intertwined with each other, forming a kind of air cushion near the surface of the skin, protecting the bird’s body from hypothermia.

The plumage has different colors and shapes and carries information not only about the species, but also often about the gender of the bird. Appearance plays an important role in both intraspecific and interspecific communication.

General structure of the feather

The plumage performs many functions, and each individual element may differ in appearance. Next we will look at what bird feathers are like. The structure and composition of the plumage have much in common, regardless of purpose. Feathers are made of keratin protein. Made from the same material as our nails and hair.

The structure of a bird's feather is as follows: shaft, feathers, barbs, barbules, hooks. The basis of each feather is the central shaft. It ends with a hollow edge, which is attached to a feather bag located in the skin. This name dates back to the time when goose feathers were used for writing. Their ends were sharpened, that is, sharpened.

The upper part of the feather, on which the barbs are located, is called the shaft. Elastic filament-like formations - first-order beards - are attached to the trunk at an angle of 45°. They contain even thinner and smaller threads - barbs (they are also called second-order barbs).

There are hooks on the barbules, with the help of which the barbules are fastened together and form an elastic and dense fan that can resist air pressure during flight. If the hooks come loose, the bird uses its beak to straighten them. The mechanism is often compared to a zipper. The beards in the lower part of the fan do not have hooks and make up its downy part.

Types of feathers

Based on their structure and functions, feathers can be divided into several types:

• contour;
• helmsmen;
• flight feathers;
• downy;

Despite the fact that outwardly feathers seem quite simple, in structure they are complex and ordered structures and consist of many small elements. The structure of the feather depends on the functions performed.

Outline feathers

Contour feathers are so called because they form the outline of the bird's body and give it a streamlined shape. They are the main type of plumage and cover the entire body. The structure of a bird's contour feather is as follows: the shaft is rigid, the barbules are elastic and interlocked. These feathers are not distributed evenly on the body, but in a tiled pattern, which allows them to cover a large surface of the body. They are attached to the pterilium, special areas of the skin. The structure of the bird's contour feather forms a dense fan that almost does not allow air to pass through.

Tail and flight feathers

Tail feathers are found on the bird's tail. They are long and strong, attached to the coccygeal bone and help change the direction of flight.

The flight feathers are strong, they form the plane of the wing and are designed to ensure flight. They are located along the edge of the wing and provide the bird with the necessary lift and thrust. The lower part of the bird's wing is covered by one of the varieties of contour feathers - coverts.

Down feathers and fluff

Down feathers are located near the surface of the body, under the contour feathers. The structure of a bird's down feather has its own characteristics: the shaft is very thin, and there are no hooks on the barbules. These feathers are soft and airy. They are located between the down and contour feathers. The structure of a bird's down feather allows it to provide thermal insulation.

The down resembles a down feather, but with a greatly shortened shaft. The beards also do not have hooks, they are soft and extend from the edge in a tuft.

Other types of feathers

The structure of feathers can be very interesting. There are many birds, or rather their species, and they may have their own characteristics. For example, some species have filamentous feathers. They are very thin structures with a long shaft and only a few barbs at the very end. Scientists still don’t know exactly what their function is. Presumably the filamentous feathers are sensory organs and help determine the position of the flight feathers.

The structure of feathers (of some bird species), related to the sense organs, is always specific. For example, bristles, which perform both sensitive and protective functions, have a soft shaft and several barbs at the base. They are located on the head.

There are also decorative feathers - modified contour ones. They have a variety of shapes and colors and serve to attract females. An example is the rich peacock tail.

Most bird species have a special gland that produces a secretion with which animals lubricate their feathers. This protects them from getting wet and makes them more elastic. But there are birds that do not have such a gland, and its function is performed by powder feathers. In this case, the structure of the bird's feather is simple - it consists of one shaft, which, as it grows, breaks and crumbles into tiny particles, forming a kind of powder that protects the plumage from getting wet and sticking together.

Feather growth

The structure of a bird's feather can be quite complex, and its development is just as difficult. Like hair, feathers grow from a follicle. At the beginning of development, each new feather has an artery and vein in the shaft that feed its growth. The trunk of the developing feather is dark at the beginning; it is called blood feather. After growth is completed, the ear becomes transparent and blood no longer flows.

The nascent feather is protected by a waxy keratin sheath. At a certain stage of development, the sheath is removed by the bird while cleaning its feathers. Once, twice, or less often three times a year, the bird completely changes its plumage. Old feathers fall out on their own and new ones take their place. This process is called molting. Most birds molt gradually without losing their ability to fly. However, there are also species that lose all their flight feathers and cannot fly. For example, ducks, swans.

Coloring

The structure of a bird's feather also affects its color. Factors affecting feather color can be divided into two groups: physical and chemical. Chemical factors include the presence of various pigments in feathers. Linochromes in varying concentrations provide yellow, light green and red colors, melanins - brown and black.

Physical factors include the feather cells and the angle of incidence of the rays. This produces green, blue, purple tints and a metallic sheen.