The birds form with approximately 8660 types, with what the number fluctuates according to opinion of 8548 to 8809 types, what tackles the species-wealth, a very big class of the vertebrates. Sundries zoologist from what the fluctuation of the species-number declares itself classifies individual bird-forms differently as subtypes or own types. Because the "Vogeltyp" is very uniform, a systematic arrangement of this class falls heavily. So, also the division is quite irregular (24-29) in order; here, the approximately 145-155 living (today living) families are apportioned in 26 bird-order:

1. Coccyx-chickens, 2. Run-birds, 3. Rag-divers, 4. Loons, 5. Penguins, 6. Tube-noses, 7. Ruderfüßer, 8. Waders, 9. Flamingos, 10. Goose-birds, 11. Gripping-birds, 12. Hen-birds, 13. Crane-birds, 14. Wade - and seagull-birds, 15. Pigeon-birds deaf persons, 16. Parrots, 17. Cuckoo-birds, 18. Owls, 19. Night-swallows, 20. Sailor-birds, 21. Kolibris, 22. Mouse-birds, 23. Trogons, 24. Rackenvögel, 25. Woodpecker-birds, 26. Sparrow-birds.

The far species-richest and "most modern" order is that of the sparrow-birds in 50 families with approximately 3500 types. The barely 800 known fossil (died out) bird-types are contained not in this system, probably however a whole row of first "recent", since that 17. Century, died out or exactly in these decades through direct prosecution or through the rapidly increasing ecocide of the earth of vanishing bird-types.

Has the birds and the reptiles the birds a common origin, the Archosaurier, descent and becomes from this zoologist as Sauropsiden summarized, since she/it a whole row of more together anatomical physique-like characteristics (Z). B. Sheds, shows. The first birds were created in the Erdmittelalter (Mesozoikum) against end of the law-age approximately 150 million years ago.

"Urvogel" Die oldest known fossil-findings come Solnhofens in Bavaria from the upper law. in 1861, one found the first track (a feather-mark) of a fossil bird there, later then altogether 3 properly well gotten skeletons of the Urvögel. Since the anatomical differences of the found copies are low, one assigns all "Urvögel" of this an Art of Archaeopteryx lithographica.

The Urvögel still have teeth (with a cap from glaze) 3 fingers as reptile-characteristics in the waiter and lower jaw, 3 not together deformed means-hand-bones (Metacarpalia), with ever 2, 3 and 4 phalanxes (Phalangen) and claws, with what the 2. Finger befiedert was and carried sheds presumably the two others, neck-ribs and a long tail with spinal column of 21 fuss.

On the other hand, the Urvögel show already a series of typical bird-characteristics: a well developed plumage with typical bird-feathers, largely together deformed skull-bones, lower leg and foot-bones: Shin (tibia) and tarsi (Tarsalia) merge to the Tibiotarsus and further tarsi with metarsals (Metatarsalia) to the Tarso-Metatarsus or "run", so that the "heel-joint" actually is a joint like with the present-day birds between the tarsi (Intertarsalgelenk). Further, the Urvogel has 3 front-toes and a long rear-toe (Hallux), to the fork-leg (Furcula) of healed collarbones and a to the back directed shame-leg (Os pubis).

Probably the Urvögel lived in the treetops of the Jurassic forests and looked (skull-anatomy) for fruits and insects there; her/its/their flight-fortune was very big presumably not yet since the breastbone is developed relatively weakly.

Petrifactions country-living in birds are extremely rare - reached the 3 Urvögel into the muddy settlements of the law-sea through any process very happy for the science and preserved there fast - while findings of petrified unairworthy Meeresvögel, numerous from the later chalk-time, are known. You/they probably hunted after fishings in the chalk-sea with her/its/their bezahnten jaws. Already numerous forerunners of some still today living bird-families find themselves in the most uppermost chalk.

All present-day bird-order existed already on the end of the Eozäns (43-37 million years ago). In the Pleistozän (ice age-ages) finally, most of the living bird-types were created; the species-number was with approximately 10 600 types at that time even higher than today.

Physique birds therefore later than the (in the triad) mammals also putting aside from the reptiles, with whom they have a whole row of morphological characteristics in common because of parallel-development, originated: So, also birds are equally-warm (homoiotherm) with separate auricles (atria) and main-chambers (ventricles). Consequently, lung-cycle and body-cycle are completely of each other separate. The body-temperature lies approximately higher than with mammals with birds in the average about 6 °C. However the right arterial-bow developed into the aorta with the birds while the left bow turns into the aorta with the mammals. With fishings and reptiles (both - except for the crocodiles - don´t have yet any separate cycles), both arterial-bows are trained as aorta.

Bird-lung in close context of the very by virtue of-lavish fly is the heart of the birds in the relationship to the entire body far bigger than this of the mammals. Also the lung works after another principle. She/it constantly becomes durchströmt in a direction through a "bellows-system" existing only with birds from dünnhäutigen Ausstülpungen of the lung (airbags) with fresh breath-air while the mammal-lung then forms a "dead end", in which fresh air in-streams, lingered in it a moment so to speak and the breath-organ leaves again after it in the same way. The whistle or Durchströmlunge of the birds calls on much less place and (there is not any "dead air") manages a very much bigger gas-exchange in the same time as the mammal-lung. However, much oxygen is u. a. the most important prerequisite, to look after about the considerably developed breast-musculature sufficiently during the often mightily long flight-routes. The energy-supply takes place on that occasion from the fat-metabolism and not, as with mammals, from the reduction of carbohydrates.

The together merged bones of the skull still are skeleton as adaptation at flying beside the Pneumatisation of the bones through airspaces (one airbag-pair fills even the two upper arm-bones), the shoulder-belt as well as, to mention the basin-bones and fuss of the loins and tail-region. The most important equipment to flying is the plumage with the birds of course.

Pass feather-structure bird-feathers from 2 quills with a common feather-spool (Calamus) and ever one flag originally. The upper part of the keel, at which the flag positions, is called shaft (Rhachis). With most bird-types, a shaft is developed (main-shaft) significantly more strongly than the others (anus-shaft), or either part had merged to an uniform structure, of which the doubles-structure recognizable only in the cross-section still reminds at the original Federtyp, together with his/its flag.

From the shaft (Scapus), the feather-branches (Rami), that are through 2 different lateral turn-offs, the hook-rays and bow-radiations, interconnected to the low extent of porous, uniform surface or feather-flags (Vexillum) to one among each other on the other hand, come off symmetrically on each side at the side. Both feather-radiations (Radii) verhaken itself among each other, in that the (to the feather-top trained) hook-rays with small hooking intervene little (Hamuli) into the bow-rays reminding to the feather-spool. If the feather-flags now tear apart through easy damages of the plumage at the feather-rays, so the bird with his/its beak can arrange the uniform feather-surface again without further.

Sundries feather-types the just described Federtyp forms the contour-feathers (Pennae). You/they give his/its smooth, current-favorable surface to the bird-body and form also the surfaces for the buoyancy. If these contour-feathers originate from at the together merged hand-bones of the wings, so one calls energy-feathers or Handschwingen (10-11 per wings) her/it/them; if however, they solid-grew at the forearm, they are called Armschwingen (18 each). The contour-feathers of the tail are called tax-feathers.

Dunenfedern Unter the contour-feathers get along the Pelzdunen (Plumae) with the adult bird. You/they serve the heat-isolation and the buoyancy (with water-living in bird-types). The shaft is soft, and the also soft flag, little lack they hooking. With many squabs, a dense dress is developed already at the abandonment of the egg from Nestdunen. These feathers form the tops at the installations of the later contour-feathers (Praepennae) or Dunenfedern (Praeplumae) so to speak.

With the Nestdunen, the feather-branches put down all at the common feather-basis and not at a long, central shaft at.

Puderdunen Einige bird-groups (Z). B. Herons and parrots, Puderdunen did, with which the top of the growing back feather constantly disintegrates to fine dust, with which the birds clean her/its/their plumage and water-reject. Often, the Bürzeldrüse is strongly receded with these bird-types or is missing completely (run-birds, deaf persons, woodpeckers, parrots, Trappen).

Bürzeldrüse Diese gland is the single skin-gland of the birds - apart from small glands and the outer ear-openings -. She/it separates a greasy secretion, with which the plumage water-rejects, from is greased. With young nestlings, this gland is not yet able to function; here, the alto-birds grease her/its/their boys.

Molt birds changes her/its/their plumage regularly in order to replace this way zerschlissene feathers and to remain airworthy or to exchange with a brood-dress equipped colorful or with particularly molded jewelry-feathers or splendor-dress about the simple silence-dress. On this occasion, strong sex-differences (Sexualdimorphismus) can occur. Many bird-types molt all hand and Armschwingen and tax-feathers simultaneously; they become unairworthy consequently, Z. B. Fire-geese and cranes, while other individual feathers throw off one after the other in certain rhythm and reproduce, Z. B. Woodpeckers.

Birds took secretion in adaptation at the extremely dry habitat of the air a particular way of the Exkretausscheidung. You/they don´t synthesize the osmotically very active urine-material (this much water to the transportation into the kidneys and blister-tissue requires) like mammals as by-product of the albumen-change (from the nitrogen of the amino acids) but don´t excrete the osmotically inactive, know-crystalline urine-acid. Meeresbewohner among the birds drink saltwater and give away the surplus salt again through special glands over the eyes.

Conquered the airspace, the country (run-birds) and the sea (penguins) successfully for itself reproduction birds. Some types get only the deposit of the eggs and brood on the ground (Z). B. Tube-noses, and spends the rest of her/its/their life in the air or on the water.

The deposit of the eggs is a characteristic common all birds. There are admittedly viviparous reptiles and ah-killing mammals, this is applicable to fish and amphibians resembles, but no viviparous birds. Probably it would be a longer Tragzeit and the weight-change interconnected with it for the birds as a plane too unfavorable although bats and probably also the flight-dinosaurs are quite viviparous on the other hand as well as. was. Maybe the birds completely simply didn´t "make up" the birthing living boy either.

Some birds (Z). B. Run-birds and goose-birds, well developed copulation-organs have, while other bird-groups not any or a simply built penis possesses. Only one is with female birds in general, in fact the left ovary (Ovar) develops while 2 germ-glands (testicles) exist with the males.

The follicles - or ovulation - the free-development of the ovum - can through diverse attractions (like Z). B. Sight of a Geschlechtspartners, is caused. In the opening of the rush-pus, the egg remains some minutes and becomes from in the rush-pus entlanggewanderten seed-cells (sperm) fertilizes. Muscle-movements of the rush-pus transport the still unfinished egg in direction of the sex-opening after it. Become already furchenden seedling in the rush-pus the yolk (existing from 1/3 proteins and 2/3 fats and fat-similar materials as well as vitamins and mineral-salts) and him/it itself first the Eiklar ("protein"): Proteins, salt and water, the egg-skin and finally the Eischale taken up. In contrast to the soft-shell eggs of the reptiles, the peels of bird-eggs calcified (up to 94 percent of lime-salary) strongly; however, they admit a gas-exchange to the respiration. Through the muscle-movements of the rush-pus (his/its last part one as uterus marks), bird-eggs get her/its/their arttypische form.

Bird-eggs contain all nutrients, vitamins and trace elements, that the embryo needs for his/its development. The oxygen imperative to the metabolism is picked up by the solid peel through. The eggs of Nestflüchtern contain more yolk than eggs of equally big, as nest-stools of slipping bird-types. In him/it a case already is shortly largely independently the chicks after slipping, while completely helplessly nest-stools, unbefiedert and crawls usually blindly from the egg and is fed by the parents long.

Many birds erbrüten only 1 eggs, while the biggest nests with 20-22 eggs occur with hen-birds. With some types, also 2 or several females put her/its/their eggs into a common nest. Many bird-types pull up several yearly-broods consecutively in a reproductive-period.

Brood and slip of the young some bird-types (big-foot-chickens) use foreign-heat to the incubation of her/its/their eggs. However, most birds warm her/its/their eggs in the breast and stomach-plumage. With some types, the sexes involved at the brood have brood-stains (feather-loose skin-parts of breast and stomach), at which the body-heat can reach better to the eggs, as through the insulating plumage. With many types, both partners brood, with others only the female or more rarely - exclusively the male (Z). B. Emperor-penguin. The brood-temperature lies with approximately 34 °C. The eggs frequently are turned during the brood in order to guarantee such an even Erwärmung. Many other factors, how sufficiently u moisture, no excessive Erwärmung through sun-no-radiation, none or only few weak disruptions. a. is important for a successful brood. The shortest brood-duration amounts to 11 days, that longest approximately 12 weeks.

The lime-peel became short before slipping thinner through lime-reduction of the embryo. The squabs often give reputations of itself, that often serve the synchronization of the Schlüpfvorganges or are for the relationship between alto-bird and nestling of crucial importance, already before abandonment of the egg. The squab rubs and pecks from indoors the Eischale on, until a small hole is built. A small, hard hump, trained the egg-tooth, fall on the top of the waiter-beak and with some bird-types to it on the low beak-part the few day after slipping or is receded. The entire Schlüpfvorgang - according to bird-type - lasts some minutes or up to 4 days (tube-noses).

Sinnesleistungen Sehr known is the tone-behavior of the birds, that often is extremely complicated and serves the communication between the members of a bird-type. Birds don´t generate the many different reputations, as all other vertebrates with exception of the fish, with the larynx (larynx) but with the Aufgabelung of the windpipe called Syrinx into the Bronchien.

Also the hearing is as efficiently as the station trained as a recipient of the sound with the birds. A bird-ear does the multiple of the ear of the mammals (with exception of the whales) with reference to both the temporal dissolution-fortune and in the differentiation of individual frequency-areas.

Exactly vice-versa, however, the sense of smell is. With exception some of less bird-types (Z). B. Neuweltgeier [vultures], honey-indicators and tube-noses, is not yet unequivocally proved so far, that birds get the bearings smell-like.

The eyesight is very well developed with birds on the other hand. As well as the exact seeing on wide distances (Z). B. with gripping-birds, as also the film speed, therefore seeing with low light-intensities (owls), is the optical bearings-fortune of the mammals wide with birds thinks.

Birds and human being always, the human being envied the birds her/its/their flight-fortune and therefore and probably also gave them some attention because of the plumage-drawing splendidly colorful with many types as well as because of the beautiful chant many Singvögel. Beside the economic benefit (Z). B. House-chicken, the bird-attitude is the nature of so largely estranged environment above all for nature-lovers and particularly for the present-day human being in his/its from severe importance. Beside dogs and cats, budgerigars and the many are the pets held most frequent to the "mental edification" as "exotic persons" of marked small, colorful Singvögel (above all splendor-finches, Estrildidae) surely.

Ornithose Bei of proper attitude and care of the befiederten housemates is also she/it earlier than "parrot-illness" to prevent Ornithosis - a virus-illness very dangerous also for the human being conceivably - marked largely. Modern medications can prevent the otherwise occasionally fatal consequences at timely recognition and treatment.