How feathers grow. Bird feather structure
On one feather of a bird, under a microscope, you can count hundreds of thousands of barbules and millions of their branches with hooks.
In each contour feather, one can distinguish such components as a trunk and webs, usually asymmetrical, formed by a system of barbs. Closer to the edge of the fan, they have a downy part, the beards of which are thin, long and not interlocked with each other. Often here, on the border between the edge and the dense part of the rod, an additional rod comes off. It has small fans or can be replaced with a ball of fluff
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In addition to the typical contour feathers, birds have down feathers. Their shaft is thin, and the beards are very soft, long, sparsely set and not interlocked with each other. If the shaft is shortened and the soft barbs extend from one point, this formation is not called a feather, but down. Real down, and down feathers are connected by a series of transitions.
A similar structure is characteristic of contour feathers, which determine the outline of the bird. The most important among the contour feathers are the flight feathers of the wing and the tail feathers that form the tail. The number of feathers varies among different birds and they require careful care. Birds, like reptiles, are characterized by molting.
Feathers do not completely cover the body of birds (for example, a pigeon), but are located only on certain areas of the skin - pterilia, between which there are areas devoid of feathers - apteria (Fig. 1). This arrangement of feathers is associated with flight, since the arrangement of feathers in sections is convenient for muscle contraction during flight. Only a very few, mostly flightless, birds lack apteria, and feathers evenly cover the entire body.
The feather (Fig. 1) consists of an elastic trunk and softer side plates - outer and inner webs. The upper part of the trunk, to which the fans are attached, is called the rod and has a quadrangular shape in cross section, with the upper surface of the trunk being convex, while the lower one bears a longitudinal groove. The lower part of the trunk, devoid of webs, is called the edge and has a round cross-section, and is equipped with a hole at the base. While the inner part of the trunk is occupied by a cellular core, the cavity of the horn contains a chain of delicate horny caps inserted into each other - the soul of the feather, which is a dead papilla that fed blood to a young, growing feather.
Rice. 1. Outline pen. The quill is opened to show the bow of the feather: 1 - shaft, 2 - outer blade, 3 - internal blade, 4 - trunk, 5 - blade, 6 - blade opening, 7 - stem of the feather.
Each fan is formed by numerous beards of the first order, on which sit smaller beards of the second order. Each of them is equipped with elongated triangular plates at the end with hooks that interlock with the same hooks of neighboring barbules of the 2nd order, which already belong to another barb of the 1st order (Fig. 2).
Rice. 2. Scheme of the structure of the feather blade (/) and individual enlarged barbules of the second order (//) (according to Hesse) 1- shaft, 2 first-order barbules 3- second-order barbs, 4-hooks
Contour feathers (Fig. 1) make up most of the plumage of an adult bird and determine the shape of the animal's body. Separate groups of them have special names: supratail, ear coverts, upper wing coverts. The large feathers that grow along the rear edge of the wing and play an extremely important role in flight are called flight feathers or flight feathers. There are 1st order flywheels, or large flywheels, which sit on the hand, and 1st order flywheels, or small ones, which are attached to the forearm. Small feathers, but having a typical flight feather structure and located in a group on the rudimentary first finger, are called winglets. The large tail feathers that act as a rudder during flight are called tail feathers, or rudders. Down feathers usually sit under the contour feathers, have a thin shaft and are devoid of hooks, due to which they do not have solid webs that seem to be cut out. Down is a downy feather whose shaft is shortened so that all the barbs extend from its top in one tuft.
Thread-like feathers and bristles are located in most birds near the corners of the mouth and are down feathers that have retained the shaft, but have lost all the barbs; they have nothing to do with the hairs of mammals, despite their external resemblance to them.
The arrangement of the flight feathers is adapted to flight. The flight feathers have relatively narrow outer and wide inner webs, located in the deployed wing so that the outer web covers only the edge of the inner web of the adjacent flight feather. Due to this arrangement and the fact that each feather is capable of rotating somewhat around its axis, when the wing is raised, air passes freely between the feathers; on the contrary, when the wing is lowered, the feathers form a continuous surface that provides strong resistance to the air.
Feather placement.
Contour feathers do not grow all over the bird's body, but on certain areas of the skin, between which there are areas of skin devoid of feathers. This arrangement of feathers provides greater freedom of movement for birds in flight. In flying birds these areas are clearly defined. In ostrich birds and penguins, contour feathers evenly cover the entire body; they do not have areas free from feathers.
1 - AREAS COVERED WITH FEATHERS
2 - AREAS WITHOUT FEATHERS
Feathers are modified horny scales, similar to the scales of reptiles. Real scales can be seen on the non-feathered areas of a bird's legs. The horny sheaths on birds' beaks and claws have the same origin as feathers.
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Difference between contour and down feathers
Feather is an excellent heat-insulating and waterproof material.
Bird feathers originate from the scales of reptiles and, among other things, consist of horny substance. They, like the scales of reptiles, are considered to be derivatives, as a rule, of the superficial, epithelial layer of the skin (epidermis), and consist of dead and strongly modified cells.
Several types of feathers are recognized by their structure: contour, down, filamentous, down and bristles.
Feather types: contour feathers, down feather, down feather, filament feather, bristle feather.
Feather structure: feather, the inner part of the fan, the outer part of the fan, the downy part of the fan of a contour feather, the shaft, the side (additional) shaft, the upper navel of the feather, the lower navel of the feather, beards of the first order, beards of the second order, hooks.
Contour feathers cover the bird's entire body, forming the wings and tail and giving it a distinctive "bird-like" appearance. Externally, the contour feather is divided into a surrounding shaft and fan in the axial lobe. The lower, free part of the rod is called the edge. It has an internal cavity that is filled with spongy tissue. At the lower end of the feather, the cavity opens with a small hole - the lower navel of the feather, and at its upper end, on the border with the fan, there is, in accordance with this, the upper navel. The rod in the area of the web is the densest in texture, has no internal cavity, and its core is formed by keratinized cells filled with air. The fan itself is formed by small “branches” receding in two directions from the rod - beards of the first order. They are so closely interlocked with each other that they resemble a continuous plane. But if you look closely, or even better, put a contour pen under a microscope, you will see that from any beard of the first row, smaller beards, called beards of the 2nd row, or beards, recede in rows on both sides. If you look at this area even closer, then on any beard of the 2nd row you will find a certain number of tiny hooks. It is with their help that neighboring barbs are linked to each other, as a result of which a continuous plate appears.
The structure of a down feather is the same as a contour feather, with the difference that the barbs on down feathers are delicate and do not have hooks, therefore the barbs of the first row are not interlocked with each other. There is an assumption that feathers with unlinked barbs are simpler than contour feathers, and as indirect evidence one can cite the precedent that ratites (a very old collective category that includes African ostriches, cassowaries, rheas and kiwis) do not have feathers with linked barbs. Down differs from down feathers in the absence of a shaft - its beards, not yet connected, recede from the edge.
Down, down and feather mixtures.
A feathery and fibrous substance, small hairs of an animal's body (under feathers, under fur), characterized by softness, fineness and tenderness. (Explanatory Dictionary of Ushakov).
Down differs from feathers in that it has a thin, very short shaft and long thread-like barbs that are not interlocked into a plate. The length of the edge is small - less than 1 mm. The length of the blade part with the rod can reach 10-25 mm. The barbs extend symmetrically from the shaft, but their number per 1 mm of shaft length is greater than on the feather, and they are much longer. The beards of the fuzz have rays, the length of which is about 1 mm; The thickness of the down beards is about 5-7 microns, they are strong, flexible, elastic, so the down practically does not feel, which determines its high quality. Sometimes in the feather cover of birds there are feathers of an intermediate type between contour and down. They have a relatively long and elastic shaft, but the beards are not interlocked into the blade of the fan. Such formations are called down feathers. Down exists only in waterfowl. The most valuable down is the white goose. Gray goose and duck down are also often used.
How does down protect against the cold?
The feather ball should insulate the body from the cold outside air. And for this, down, like any other insulating material, retains warm air heated by the body in itself. Down forms a reliable barrier against the cold. Due to the fact that each fluff has a very complex, branched structure, fluff is able to hold much more warm air than any other synthetic material, and at the same time prevents the movement of air inside the ball. This property of down feather raw materials is called hygroscopicity.
Goose, duck (waterfowl) down
Despite the large number of artificial insulation materials, down is still considered an excellent insulation material based on a set of requirements: not very heavy weight, high thermal insulation properties, small transport volume, long service life. The properties of down are explained by the texture of the down, consisting of individual downs that push against each other to fill the size available to them, providing excellent thermal insulation. On the other hand, when compressed, the fluffs “enter” each other, providing a small transport volume. With proper care, the service life of goose down products is 15-20 years, duck down 8-10 years.The main parameter by which down is evaluated is its elasticity, characterized by the “Fill Power” or F.P. parameter. (volume in cubic inches to which 1 ounce of fluff, pre-compressed, is restored, the so-called filling capacity). The higher the number, the better the down feature and the greater its heat-saving characteristics. In sports and travel clothing, sleeping bags, white and grayish goose down with the F.P. characteristic is used. from 650 to 800.
The second feature is the amount of feathers in the down-feather mixture. As a rule, this sign is shown through a fraction - 90/10, which means 90% fluff, 10% feather. The higher the down content and the less feather content, the much better and more expensive the down. It is impossible to achieve a complete absence of feathers in the mixture. The best types of down contain approximately 5% feathers. This trait directly has a big impact on Fill Power, the smaller the feather, the higher the FP.
The properties of fluff are determined, as a rule, by the quality of the raw materials. Geese with white plumage, such specialized breeds as Italian, Rhine, Lindovskaya, Vishtins, Hungarian, North German, are considered the best for collecting down. To a large extent, the properties of fluff are greatly influenced by natural incidents in poultry keeping. It is not for nothing that raw materials selected in Ukraine are incredibly valued in the West - the fluff is the largest and its content in the raw materials is greater. For the same reason, feathers produced in China get a bad response. The highest quality raw material collected during manual plucking of an adult bird during its lifetime, since it contains practically no lint, the presence of which greatly affects the elastic properties of the down.
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Feathers
"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, 7, 8 upper navel (Fig. 1,). 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. 9 The fan itself is formed by small “branches” extending in both directions from the rod - beards of the first order(Fig. 1, VII, ). 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, 6 or
beards (Fig. 1, similar to the structure of the contour one, with the only difference being that the barbs on the down feathers are soft, devoid of hooks, and therefore the barbs 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. And filament feathers 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.– 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 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)..
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 provides 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 distinguished 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, And top.
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
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 coverts of the propatagium, 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. 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, coraciiformes, 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.
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
) – 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 moult, 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 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.
One of the characteristic features that distinguishes birds from mammals is their plumage. Its main function is to maintain a relatively high body temperature of the bird despite fluctuations in ambient temperature. In addition, plumage plays an important role in flight, and also serves for communication between individuals (for example, during mating or fighting for territory in order to impress an opponent). Plumage that matches the color of the environment can be a good camouflage and an auxiliary device in the struggle for existence.
In most bird species, feathers are covered with a thin layer of sebaceous secretion from the coccygeal gland and feather dust. Birds use their beaks to squeeze out the secretion from the coccygeal gland and distribute it throughout the plumage. Feather dust is formed from decaying down feathers and the exfoliating stratum corneum of the epidermis. Those species of birds in which the coccygeal gland is absent or poorly developed (for example, pigeons, certain species of parrots) produce more feather dust. Feathers coated with coccygeal gland secretions and feather dust repel water, so a healthy bird never gets completely wet. This is vital for birds, since with wet plumage in a moment of danger they would not be able to immediately take off. Distinguish three types of feathers:
Cover feathers form a characteristic contour of the body and are therefore also called contour. Like tiles, they are layered on top of each other and cover the small body of the bird, protecting it both from moisture and cold, and from the harmful effects of ultraviolet radiation. The contour feathers located on the body are round and oval in shape and have a small soft shaft. The flight feathers on the wings are arranged as necessary for flight. The same feathers on the tail serve as steering feathers during flight, and as guides during takeoff and landing. They have a strong, long shaft and unequal fans located on either side of the shaft. The feathers that cover the underside of the flight feathers are a type of contour feather and are called coverts. Other types of feathers are ear coverts - covering the auditory opening; and often special crest feathers covering the head. 
The structure of all integumentary feathers is the same, although they differ markedly in size on different parts of the body. Each feather consists of a shaft and a fan. The shaft is distinguished by a trunk that becomes thinner towards the top and a ridge fixed in the feather papilla (in the skin). The integrity of the fan is ensured by the first-order beards extending from the shaft, from which second- and third-order beards with cilia and hooks extend. The hooks of the third-order beards firmly cling to the second-order beards, as a result of which the fan is a single elastic surface. If this adhesion is disrupted due to any external influence, the bird can easily restore it by clearing the feathers with its beak.
But if the integrity of any part of the fan is damaged (for example, due to constant friction against the bars of a cage that is too tight, or due to improper catching and holding), it is impossible to restore it. Therefore, careful handling of a bird's plumage is important for its health.
Although the fan allows air to pass through, it is dense enough to keep the bird aloft, and the beards, coated with a thin layer of wax, repel water. Each of the contour feathers can rise and fall using its own tiny muscle.
By raising or pressing the feathers towards the body, the bird retains more or less air in them and thereby controls the temperature around the body. Therefore, a frozen or sick bird “crests”, fluffing up its feathers. When a bird is hot, it appears thin and slender. Some parrots, such as crested cockatoos, raise and deflate their feathers to express emotions.
A very important type of feather is down feathers. They are located under the contour feathers and provide insulation of the bird from the cold. Birds have thin skin and usually do not have a thick layer of fat like aquatic mammals. In the cold, birds would quickly lose heat if their body were not surrounded by their own “duvet.” Down feathers are small and fluffy. They do not have second-order barbs or hooks, like contour feathers, and they quickly get wet. The down feathers remain hidden under the body feathers and are protected from getting wet.
Oily substances that get on the feathers of a bird and a long stay in water lead to the sticking of the barbs of the feathers, and the plumage loses its ability to maintain 
warm. Birds that have been in water for a long time or with oil on their feathers drown or die from hypothermia. In this regard, medicines or creams dissolved in oil should be used only in special cases and under the supervision of a veterinarian who specializes in birds.
The chicks are covered only with downy feathers. Feather dust is formed from the collapsing old fluff and exfoliating stratum corneum of the epidermis.
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. have a poorly developed fan, or it is completely absent. Many species of birds have such feathers; they are located separately - at the base of the beak, on the eyelids and nostrils.
Powders- special feathers, the main purpose of which is that, barely growing, their beards break, forming a fine powder, like dust. It is believed that this powder, covering the feathers with a thin layer, gives them additional water-repellent properties. Some species of birds do not have powder coats or have them only in some specific places. Parrots are distinguished by the fact that powders are scattered throughout their body.
Powders are especially characteristic of cockatoos and grays, in healthy individuals of which the powder creates a grayish sheen to the beak and paws. A decrease in the amount of powder produced is often the first sign of illness in birds infected with parrot beak and feather disease (PBFD) virus. A cockatoo's shiny beak and black legs are a telltale early sign of this devastating disease.
There are other feathers that are described based on their structure or function. Special feathers that deserve attention are the so-called guide feathers, surrounding the cloaca opening in birds. It is believed that the guide feathers surrounding the cloacal opening facilitate the alignment of the male and female cloacae at the time of mating.
Plumage color.
Although some parrots have brightly colored skin on non-feathered parts of the body, such as the bright yellow skin on the face of hyacinth macaws or the orange-yellow legs of some lorises, lorikeets and parakeets, parrots' feathers are brighter and more varied in color. The range of bright colors that color feathers is very diverse. The color of feathers, according to its origin, can be divided into two independent forms - the color formed by a certain pigment, and the color that arises from the special structure of the feather.
Pigment coloring is formed due to the dye that is part of the feather horn as a dye. Most regular pigments This:
- 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- creating black, brown and some yellow colors;
- carotenoids- coloring feathers yellow, orange and red;
- porphyrins- creating green and red colors.
Carotenoids are transferred into the color of feathers from food. A significant lack of these pigments in the diet can lead to a weakening of the color of the plumage.
The production of most pigment colors is regulated by the liver, so many diseases, including vitamin A deficiency, chlamydia, zinc poisoning and others, can lead to deterioration of color. Typically, abnormal coloration associated with liver disease appears as red feathers appearing in "unusual" places in Grays and Amazons, or yellowish, bronze, unusually dark feather edges in Amazons.
Another coloring option is the so-called “structural painting”. Depending on the structure of the second- and first-order barbules, sunlight is refracted and reflected from them differently. The structure of the barbs can act as a prism and mirror, decomposing and reflecting solar rays of different wavelengths, creating an iridescent shine, or act as a filter, absorbing some rays and transmitting others. The most important structural effect that appears on the feathers of parrots is “ray scattering by heterogeneity of the medium” - when sunlight falling on a feather is scattered so that only blue rays are reflected. Most blue shiny colors in birds are due to this effect.
In the color of a number of green birds, the blue color reflected “on the heterogeneities of the environment” is actually mixed with the yellow color of the carotenoid pigments of the feathers, and this combination of yellow and blue gives the green color of the feathers.
Feathers, colored white, refract and reflect all wavelengths of light that strike them. They do not contain pigments, and this makes the feathers more fragile and less resistant to wear than colored feathers.
Shedding.
1. D. Quinten “Diseases of ornamental birds”, Veterinary practice, “Aquarium”, 2011.
2. B. Watson, M. Harley “Parrots”, publishing house “World of Books”, 2007.
The basic structure of a bird's feather was considered by many of us as part of the school curriculum. If we pay more attention to this topic, it will become clear how little we know about it. The design of bird plumage is a complex ornament where nature has thought through everything down to the smallest nuances. In the article we will talk about the specifics of the formation of the feather structure, its varieties and functions that birds use in everyday life.
Plumage is not only a distinctive feature of birds and their calling card. This is a necessity that appeared among winged birds as a result of evolutionary transformations. The ancestors of birds, predatory dinosaurs, were the first to acquire plumage. They were called Sinosauropteryx.
Over time, fibrous fluff grew on the surface of their skin, protecting them from the decrease in temperature on the planet. Plumage in the form in which it exists now appeared in Microraptor and Caudipteryx.
The evolutionary processes occurring with ancient lizards due to climate change have formed unique material. Without it, the continued existence of many species of dinosaurs became impossible.
Composition and anatomical structure
The plumage has a specific structure. At its base (except for the down feather) there is a dense rod, hollow from the inside. The lower part is located directly under the skin in the so-called feather pouch. One fan grows on the surface of the rod on both sides. Each of them consists of barbs. The 1st order beards are attached directly to the shaft, and the 2nd order beards grow from them. The structure of the beards resembles small hook-shaped webs that tightly adhere to each other, forming a smooth monolith.
The material that makes up bird feathers is horny matter or keratin.
Functional plumage types
Depending on the location and functionality, there are several types of feathers.
Covert feathers give the bird's body a streamlined shape, which helps it in flight and movement. They grow on the skin like shingles. Their task is to conserve heat and protect the skin from damage. And the dense layer does not allow cold or hot air to pass through.
Flywheels of the first and second order. These are what wings are made of. These feathers are straight and long. A typical example is the goose feather, with which people wrote in past centuries. Their number per individual varies from 10 to 17 pieces. The exceptions are hummingbirds and albatrosses. Nature awarded the micro bird only 6, while the albatrosses were provided with 37 pieces.
The tail feathers resemble flight feathers, but they have a softer structure. They are flat and curved. With their help, the bird changes direction in the desired direction in flight.
Down and special types
Down feathers are divided into two subgroups. These are directly down feathers and bird fluff. The former have a dense shaft, and their beards do not interlock in the fan. The shaft of the down is almost not expressed and also does not adhere to the fan.
Special ones include:
- decorating;
- tassel;
- powders;
- vibrissae.
Vibrissae have only a shaft. They have a tactile function, which is why they are located in the beak area.
Powders are small powdery growths on other feathers that provide birds with a water-repellent effect.
Tassels grow in the area of the coccygeal gland, their structure is weakly linked.
Life cycle and its stages
Bird feathers go from embryo to aging much like human appendages on the skin. Like all vertebrates, the skin of representatives of the feathered world has two layers. These are the epidermis - epithelial tissue, and the dermis - connective tissue.
When the epidermis and dermis interact, feathers are born. At first it resembles a tubercle or the rudiment of a scale. Over time, a characteristic growth appears, the base of which, as it grows, goes deeper into the skin, forming a purse.
The growth is located on top of the epidermis, and below it there is living tissue with blood vessels. As the feather growth grows, it stretches and the keratinized tubular tissue is pushed out of the pouch. In this process, feather barbs are formed. Their appearance depends on the type of feather.
At the end of the life cycle, the cells of the feather papilla, through which feeding occurred, die. So, the beards are pushed out, after which a kind of brush is formed. This process ends the life of the old feather, after which a new young one will appear.
Feather care
The body of every living creature needs hygiene procedures. And birds are no exception - they clean regularly. Typically this process takes about two hours each day.
There are several cleaning methods. Birds flying fast accelerate and plunge into the pond. Others preen their feathers in the rain or prefer to rock in the dust. If foreign objects get into the plumage of birds, the birds pull them out with their beaks.
Often pathogenic microorganisms adhere to the plumage, damaging the elasticity of the surface. Most often, the infection affects the head. As protection, birds use fatty secretions from the coccygeal gland, which they apply to the surface of the head with their paws.
World records
Nature sometimes surpasses itself and produces unprecedented miracles. She didn't ignore the birds either. Here are some interesting facts about the record holders.
Peacocks are the birds with the most beautiful feathers on the planet. They owe this feature to the specific structure of their beards, which reflect sunlight.
Japanese ornamental roosters have the longest tail feathers in the world. Their length reaches 5 meters.
Argus, which looks like a peacock, is also famous for its long plumage. Its average tail feathers are 150 cm long.
Birds of paradise are characterized by aesthetically attractive plumage. Its color range varies over a wide range of shades. The length and outline of this natural decoration fascinates with its bizarre diversity. For example, the colorful tail of birds sometimes takes on an intricate spiral shape.
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Feathers are found only in birds and are complex structures that play an important role in flight.
- The body of a bird is obviously designed for flight, so feathers are an extremely important element.
- Feathers are among the most complex epidermal processes that exist in animals.
- Feathers have an amazing variety of colors, shapes and sizes.
Causes of flowers
Pigments of yellow and red colors enter feathers from the fatty layer of the bird. Pigments of gray, brown and black colors are from blood. The pigment melanin produces grey, brown and black colors. Lipochrome pigments are yellow, orange, and red. The color of feathers implements various functions, such as: protective coloring, attracting the opposite sex, distinguishing the sexes.
Feather structure
Feathers are divided into several types based on their functions and structure:
- contour
- flight feathers
- helmsmen
- downy
Externally, feathers can look quite simple. In fact, these are very complex and ordered structures. Despite its apparent simplicity, a feather can consist of a million components. Depending on the function, the structure of the feather can vary greatly.
Penna– forms the outline of the bird’s body. These feathers give the bird's body a streamlined shape. These feathers are the main type. Such feathers cover the entire body of the bird and are attached to special areas of the skin - pterilia. The feathers on the body are not evenly distributed, but in a tiled pattern, which allows the minimum number of feathers to cover the largest possible areas of the body.
Flight feathers- these are long feathers designed for flight, therefore they are strong and form the plane of the wing. These wings are attached along the edge of the wing. The largest flight feathers are attached to the edge of the wing; they provide the bird with the necessary thrust and lift.
The feathers that cover the underside of the flight feathers are called coverts and are a variant of contour feathers.
Tail feathers- strong and long feathers that make up the bird's tail. These feathers are attached to the coccygeal bone and are designed to turn in flight.
Down feathers.- are located under the contour feathers. Unlike flight feathers, down feathers have a very thin shaft, and the barbs do not contain hooks. These are feathers of an intermediate type, between down and contour feathers. Down feathers and down provide thermal insulation.
Pooh- differs from down feathers in that the shaft is greatly shortened and therefore the beards extend away from the edge in a tuft.
The shaft of the pen consists of two parts, the shaft and the blade. The stem is the part of the trunk to which the fans are attached. The rod has a tetrahedral cross-section in diameter. The lower part of the trunk without webs is called ochin, round in diameter. The feather in the bird's body is held in a feather bag. The beards extend in both directions from the shaft, thus forming the fan of the feather. From the barbules, in turn, branches extend in both directions - barbules. 
Half of the barbules have hooks that interlock with the other barbules that do not have hooks. In a large bird, the flight feather can contain up to one million barbules. The beards of birds are tightly linked with hooks to the next fan, which act like a “zipper.” Such a fan is quite strong, but still elastic and quite dense, so that when flying, only a little water or air can leak through the feathers. If for any reason the hooks come loose, the bird will connect them with its beak while cleaning its feathers.
Like a bird flies
The feathers must work so that the bird can provide itself with “lifting force”.
Air must flow faster on the upper surface of the wing, and slower on the lower surface, so that the air pressure above the wing is reduced. To achieve this goal, the flight feathers are not symmetrically arranged and the smaller blade of the flight feather is turned to the leading edge in the wing. The bird can also change the shape of its wing, this helps it control its flight, take off and land. This is achieved with the help of a complex system of tendons, with the help of which the bird can bend its wing feathers in order to change air resistance.
How feathers grow
