Beak - Knowledge (XXG)

381: 710: 1471:. Very long beaks are thought to be selected against because they are prone to a higher number of breaks, as has been demonstrated in rock pigeons. Beaks with no overhang would be unable to effectively remove and kill ectoparasites as mentioned above. Studies have supported there is a selection pressure for an intermediate amount of overhang. Western Scrub Jays who had more symmetrical bills (i.e. those with less of an overhang), were found to have higher amounts of lice when tested. The same pattern has been seen in surveys of Peruvian birds. 210: 1066:. The hatching chick first uses its egg tooth to break the membrane around an air chamber at the wide end of the egg. Then it pecks at the eggshell while turning slowly within the egg, eventually (over a period of hours or days) creating a series of small circular fractures in the shell. Once it has breached the egg's surface, the chick continues to chip at it until it has made a large hole. The weakened egg eventually shatters under the pressure of the bird's movements. 1464:) such as lice. It is mainly the tip of the beak that does this. Studies have shown that inserting a bit to stop birds from using the tip results in increased parasite loads in pigeons. Birds that have naturally deformed beaks have also been noted to have higher levels of parasites. It is thought that the overhang at the end of the top portion of the beak (that is the portion that begins to curve downwards) slides against the lower beak to crush parasites. 1568: 588: 924: 619: 7626: 1021: 791: 1320: 7650: 270: 247: 468: 7662: 1716: 38: 7638: 1301: 1172: 1734:. This consists of pits in the bill surface which in the living bird is occupied by cells that sense pressure changes. The assumption is that this allows the bird to perform 'remote touch', which means that it can detect movements of animals which the bird does not directly touch. Bird species known to have a 'bill-tip organ' include 1559:, use various bare parts of their bodies (including their beaks) to dissipate as much as 40% of their metabolic heat production. Alternately, studies have shown that birds from colder climates (higher altitudes or latitudes and lower environmental temperatures) have smaller beaks, lessening heat loss from that structure. 301:, attaching on either side of the head to the quadrate bone. The jaw muscles, which allow the bird to close its beak, attach to the proximal end of the lower mandible and to the bird's skull. The muscles that depress the lower mandible are usually weak, except in a few birds such as the starlings and the extinct 372:, have compound rhamphothecae that consist of several pieces separated and defined by softer keratinous grooves. Studies have shown that this was the primitive ancestral state of the rhamphotheca, and that the modern simple rhamphotheca resulted from the gradual loss of the defining grooves through evolution. 1130:

is determined by the density of the deposited pigments. For example, bright red is created by dense deposits of mostly red pigments, while dull yellow is created by diffuse deposits of mostly yellow pigments. Bright orange is created by dense deposits of both red and yellow pigments, in roughly equal

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produces "earth tones" ranging from gold and rufous to various shades of brown. Although it is thought to occur in combination with eumelanin in beaks which are buff, tan, or horn-colored, researchers have yet to isolate phaeomelanin from any beak structure. More than a dozen types of carotenoids are

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are covered with large dome-shaped opercula, which help to reduce the rapid evaporation of water vapor, and may also help to increase condensation within the nostrils themselves—both critical functions, since the nestlings get fluids only from the food their parents bring them. These opercula shrink

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and is particularly useful in feeding studies. There are several standard measurements that can be made—from the beak's tip to the point where feathering starts on the forehead, from the tip to the anterior edge of the nostrils, from the tip to the base of the skull, or from the tip to the cere (for

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of the beak overhang morphology and body morphology of parasites. Artificially removing the ability to preen in birds, followed by readdition of preening ability was shown to result in changes in body size in lice. Once the ability of the birds to preen was reintroduced, the lice were found to show

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birds are often brightly coloured, sometimes with contrasting spots or other patterns, and these are believed to be an indication of their health, fitness and competitive ability. Based on this, the parents decide how to distribute food among the chicks in the nest. Some species, especially in the

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which projects from their nares. The function of this tubercule is unknown. Some scientists suggest it may act as a baffle, slowing down or diffusing airflow into the nares (and thus allowing the bird to continue breathing without damaging its respiratory system) during high-speed dives, but this

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made of bone or cartilage that separates the two nares, but in some families (including gulls, cranes and New World vultures), the septum is missing. While the nares are uncovered in most species, they are covered with feathers in a few groups of birds, including grouse and ptarmigans, crows, and

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is large and connects with premaxillae and maxillopalatine bones in a condition termed as a "paleognathous palate". All other extant birds have a narrow forked vomer that does not connect with other bones and is then termed as neognathous. The shape of these bones varies across the bird families.

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to support this idea. There is some experimental evidence to suggest that they may prevent particles from striking the eyes if, for example, a prey item is missed or broken apart on contact. They may also help to protect the eyes from particles encountered in flight, or from casual contact from

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flap. In diving birds, the operculum keeps water out of the nasal cavity; when the birds dive, the impact force of the water closes the operculum. Some species which feed on flowers have opercula to help to keep pollen from clogging their nasal passages, while the opercula of the two species of

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Although beaks vary significantly in size and shape from species to species, their underlying structures have a similar pattern. All beaks are composed of two jaws, generally known as the maxilla (upper) and mandible (lower). The upper, and in some cases the lower, mandibles are strengthened

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Although beaks vary significantly in size, shape, color and texture, they share a similar underlying structure. Two bony projections – the upper and lower mandibles – are covered with a thin keratinized layer of epidermis known as the rhamphotheca. In most species, two holes called

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have nostrils enclosed in double tubes which sit atop or along the sides of the upper mandible. These species, which include the albatrosses, petrels, diving petrels, storm petrels, fulmars and shearwaters, are widely known as "tubenoses". A number of species, including the

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There is a suggestion that across these species, the bill tip organ is better-developed among species foraging in wet habitats (water column, or soft mud) than in species using a more terrestrial foraging. However, it has been described in terrestrial birds too, including

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or an experienced birdkeeper, involves clipping, filing or sanding the beaks of captive birds for health purposes – in order to correct or temporarily alleviate overgrowths or deformities and better allow the bird to go about its normal feeding and preening activities.

1046:. Commonly known as an egg tooth, this white spike is generally near the tip of the upper mandible, though some species have one near the tip of their lower mandible instead, and a few species have one on each mandible. Despite its name, the projection is not an actual 1307: 1305: 1303: 548:. In some gull species, the plates expand slightly at that point, creating a noticeable bulge; the size and shape of the gonydeal angle can be useful in identifying between otherwise similar species. Adults of many species of large gulls have a reddish or orangish 1306: 487:

to the ridge line of a roof, it is the "highest middle lengthwise line of the bill" and runs from the point where the upper mandible emerges from the forehead's feathers to its tip. The bill's length along the culmen is one of the regular measurements made during

947:-shaped structure, which sometimes spans the entire width of the beak, is often bent at the tip to form a hook. It serves different purposes depending on the bird's primary food source. Most species use their nails to dig seeds out of mud or vegetation, while 1507:) attention of females from a distance and then impress them with the sound volume and pattern. This explains why humans are sometimes inconvenienced by pecking that clearly has no feeding purpose (such as when the bird pecks on sheet metal repeatedly). 1542:

alone showed a much weaker correlation. By dumping excess heat through their bills, the sparrows are able to avoid the water loss which would be required by evaporative cooling—an important benefit in a windy habitat where freshwater is scarce. Several

1012:, mechanoreceptors sensitive to pressure and vibration, are found in association with rictal bristles. They may help with prey detection, with navigation in darkened nest cavities, with the gathering of information during flight or with prey handling. 1150:

range, and some species are known to have ultraviolet peaks of reflectance (indicating the presence of ultraviolet color) on their beaks. The presence and intensity of these peaks may indicate a bird's fitness, sexual maturity or pair bond status.

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have beaks which are slightly more upturned than those of males. Males of the larger gull species have bigger, stouter beaks than those of females of the same species, and immatures can have smaller, more slender beaks than those of adults. Many

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birds, but are also found in some non-insectivorous species. Their function is uncertain, although several possibilities have been proposed. They may function as a "net", helping in the capture of flying prey, although to date, there has been no

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The size and shape of the beak can vary across species as well as between them; in some species, the size and proportions of the beak vary between males and females. This allows the sexes to utilize different ecological niches, thereby reducing

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from rocks. There is evidence that the nail may help a bird to grasp objects. Species which use strong grasping motions to secure their food (such as when catching and holding onto a large squirming frog) have very wide nails. Certain types of

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Because the beak is a sensitive organ with many sensory receptors, beak trimming (sometimes referred to as 'debeaking') is "acutely painful" to the birds it is performed on. It is nonetheless routinely done to intensively farmed

4443:"A molecular mechanism for the origin of a key evolutionary innovation, the bird beak and palate, revealed by an integrative approach to major transitions in vertebrate history: DEVELOPMENTAL MECHANISM FOR ORIGIN OF BIRD BEAK" 400:) are the cutting edges of the two mandibles. In most birds, these range from rounded to slightly sharp, but some species have evolved structural modifications that allow them to handle their typical food sources better. 1159:, for example, show spots of ultraviolet reflectance only as adults. These spots are brighter on paired birds than on courting birds. The position of such spots on the beak may be important in allowing birds to identify 887:

to the cere. Although it is sometimes feathered in parrots, the cere is typically bare and often brightly colored. In raptors, the cere is a sexual signal which indicates the "quality" of a bird; the orangeness of a

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uses its bill to navigate underwater, detect food, and dig. The bill contains electroreceptors and mechanoreceptors, causing muscular contractions to help detect prey. It is one of the few species of mammals to use

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does the same with his orange sail feathers. A number of species use a gaping, open beak in their fear and/or threat displays. Some augment the display by hissing or breathing heavily, while others clap their beak.

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codes for a secreted protein also known to be expressed in mammalian craniofacial development. The combination of these signals determines beak growth along the length, depth, and width axes. Reduced expression of

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The shape of the beak is determined by two modules: the prenasal cartilage during early embryonic stage and the premaxillary bone during later stages. Development of the prenasal cartilage is regulated by genes

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The egg tooth is so critical to a successful escape from the egg that chicks of most species will perish unhatched if they fail to develop one. However, there are a few species which do not have egg teeth.

1680:. A cauterizing blade or infrared beam is used to cut off about half of the upper beak and about a third of the lower beak. Pain and sensitivity can persist for weeks or months after the procedure, and 266:. At the base of the upper mandible a thin sheet of nasal bones is attached to the skull at the nasofrontal hinge, which gives mobility to the upper mandible, allowing it to move upward and downward. 357:, such as the puffins, parts of the rhamphotheca are shed each year after the breeding season, while some pelicans shed a part of the bill called a "bill horn" that develops in the breeding season. 1114:, which is found in the bare parts of many bird species, is responsible for all shades of gray and black; the denser the deposits of pigment found in the epidermis, the darker the resulting color. 443:

bills, found in 23% of all hummingbird genera, may perform a similar function, allowing the birds to effectively hold insect prey. They may also allow shorter-billed hummingbirds to function as

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some woodpeckers. The feathers over a ptarmigan's nostrils help to warm the air it inhales, while those over a woodpecker's nares help to keep wood particles from clogging its nasal passages.

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have a sharp projection along the upper mandible, with a corresponding notch on the lower mandible. They use this "tooth" to sever their prey's vertebrae fatally or to rip insects apart. Some

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signaling would result in a reduced premaxillary bone due to the overdevelopment of the prenasal cartilage, which takes up more mesenchymal cells for cartilage, instead of bone, formation.

701:, the gape flanges remain somewhat swollen and can thus be used to recognize that a particular bird is young. By the time it reaches adulthood, the gape flanges will no longer be visible. 5527:

Park, F. J. (March 2011). "Avian trichomoniasis: A study of lesions and relative prevalence in a variety of captive and free-living bird species as seen in an Australian avian practice".

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codes for a serine/threonine protein kinase that regulates gene transcription upon ligand binding; previous work has highlighted its role in mammalian craniofacial skeletal development.

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than a chick with a higher body mass does. Studies have shown that parent owls preferentially feed chicks with ceres that show higher wavelength UV peaks, that is, lighter-weight chicks.

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may refer to the junction of the upper and lower mandibles, or alternately, to the full-length apposition of the closed mandibles, from the corners of the mouth to the tip of the beak.

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Bhullar, Bhart-Anjan S.; Morris, Zachary S.; Sefton, Elizabeth M.; Tok, Atalay; Tokita, Masayoshi; Namkoong, Bumjin; Camacho, Jasmin; Burnham, David A.; Abzhanov, Arhat (July 2015).

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ridge of the lower mandible, created by the junction of the bone's two rami, or lateral plates. The proximal end of that junction—where the two plates separate—is known as the

643:, have bright spots on the gape known as gape tubercles or gape papillae. These nodular spots are conspicuous even in low light. A study examining the nestling gapes of eight 5313:

Phillips, Polly K.; Sanborn, Allen F. (December 1994). "An infrared, thermographic study of surface temperature in three ratites: Ostrich, emu and double-wattled cassowary".

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Cunningham, Susan J.; Alley, Maurice R.; Castro, Isabel (January 2011). "Facial Bristle Feather Histology and Morphology in New Zealand Birds: Implications for Function".

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spectrum (visible to birds but not to humans). Parents may, however, not rely solely on the gape coloration, and other factors influencing their decision remain unknown.

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is a region found near the tip of the bill in several types of birds that forage particularly by probing. The region has a high density of nerve endings known as the

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chicks never develop one; chicks of both families escape their eggs by kicking their way out. Most chicks lose their egg teeth within a few days of hatching, though

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The lower mandible is supported by a bone known as the inferior maxillary bone—a compound bone composed of two distinct ossified pieces. These ossified plates (or

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Greenbert, Russell; Danner, Raymond; Olsen, Brian; Luther, David (14 July 2011). "High summer temperature explains bill size variation in salt marsh sparrows".

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Tattersall, Glenn J.; Andrade, Denis V.; Abe, Augusto S. (24 July 2009). "Heat Exchange from the Toucan Bill Reveals a Controllable Vascular Thermal Radiator".

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The shape or color of the nail can sometimes be used to help distinguish between similar-looking species or between various ages of waterfowl. For example, the

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The amount of contact involved varies among species. Some gently touch only a part of their partner's beak while others clash their beaks vigorously together.

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that aid in foraging by prying or gaping actions. In most birds, these muscles are relatively small as compared to the jaw muscles of similarly sized mammals.

2963: 1503:, use bill clapping as a form of communication. Some woodpecker species are known to use percussion as a courtship activity, whereas males will get the ( 1479:

declines in body size suggesting they may evolve in response to preening pressures from birds who could respond in turn with changes in beak morphology.

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significantly decreased the depth and length of chicken embryonic beak due to the underdevelopment of the premaxillary bone. Contrarily, an increase in

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theory has not been proved experimentally. Not all species that fly at high speeds have such tubercules, while some species which fly at low speeds do.

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Ito, Yoshihiro; Yeo, Jae Yong; Chytil, Anna; Han, Jun; Bringas, Pablo; Nakajima, Akira; Shuler, Charles F.; Moses, Harold L.; Chai, Yang (2003-11-01).

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vegetation. There is also evidence that the rictal bristles of some species may function tactilely, in a manner similar to that of mammalian whiskers (

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can form along the cut edges. Food intake typically decreases for some period after the beak is trimmed. However, studies show that trimmed poultry's

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concentrations. Beak coloration helps to make displays using those beaks more obvious. In general, beak color depends on a combination of the bird's

853:, have a fleshy rosette, sometimes called a "gape rosette", at the corners of the beak. In the puffin, this is grown as part of its display plumage. 427:

Birds in roughly 30 families have tomia lined with tight bunches of very short bristles along their entire length. Most of these species are either

831:, the operculum has evolved into a soft swollen mass that sits at the base of the bill, above the nares; though it is sometimes referred to as the 6533: 3510: 471:

A bird's culmen is measured in a straight line from the tip of the beak to a set point — here, where the feathering starts on the bird's forehead.

1754:, who are known for their dextrous extractive foraging techniques. Unlike probing foragers, the tactile pits in parrots are embedded in the hard 1633:

Use of the term extends beyond avian behavior; "billing and cooing" in reference to human courtship (particularly kissing) has been in use since

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male house sparrows—like female house sparrows—have brown beaks. Castration also prevents the normal seasonal color change in the beaks of male

420:. The tomial teeth of falcons are underlain by bone, while the shrike tomial teeth are entirely keratinous. Some fish-eating species, e.g., the 2055: 975:" have dark nails, while most adults have pale nails. The nail gave the wildfowl family one of its former names: "Unguirostres" comes from the 4621: 2006: 380: 6045: 6026: 6003: 5984: 5965: 5946: 5927: 5908: 5889: 5870: 5828: 5622: 5579: 5472: 5438: 5405: 4425: 4391: 4366: 4335: 4258: 4224: 4142: 4117: 4066: 3907: 3850: 3825: 3748: 3616: 3589: 3493: 3460: 3363: 3332: 3301: 3276: 2846: 2829: 2802: 2694: 2664: 2561: 2536: 2511: 2189: 2126: 1989: 1873: 262:

called the intermaxillary. The upper prong of this bone is embedded into the forehead, while the two lower prongs attach to the sides of the

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along the North American coastlines show a strong correlation with summer temperatures recorded in the locations where the sparrows breed;

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Parkes, A.S.; Emmens, C.W. (1944). "Effect of androgens and estrogens on birds". In Harris, Richard S.; Thimann, Kenneth Vivian (eds.).

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Red gape color has been shown in several experiments to induce feeding. An experiment in manipulating brood size and immune system with

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of the bones of the beak. The rhamphotheca grows continuously in most birds, and in some species, the color varies seasonally. In some

1163:. For instance, the very similarly-plumaged king and emperor penguins have UV-reflective spots in different positions on their beaks. 5087:

Clayton, Dale H.; Moyer, Brett R.; Bush, Sarah E.; Jones, Tony G.; Gardiner, David W.; Rhodes, Barry B.; Goller, Franz (2005-04-22).

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raptors and owls) — and scientists from various parts of the world generally favor one method over another. In all cases, these are

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The base of the upper mandible, or the roof when seen from the mouth, is the palate, the structure of which differs greatly in the

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hold each other's beaks in a prolonged "kiss". Billing can also be used as a gesture of appeasement or subordination. Subordinate

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Clayton, D.H.; Walther, B.A. (2001-09-01). "Influence of host ecology and morphology on the diversity of Neotropical bird lice".

1762:) of the bill, rather than the bone, and along the inner edges of the curved bill, rather than being on the outside of the bill. 1425:

often wave their formidable beaks at competing birds who get too close, clearly signaling "this seed's mine, you can't have it."

186:, the terms beak and bill are generally considered to be synonymous. The word, which dates from the 13th century, comes from the 907:

The color or appearance of the cere can be used to distinguish between males and females in some species. For example, the male

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Birds from a handful of families—including raptors, owls, skuas, parrots, turkeys and curassows—have a waxy structure called a

297:), which can be U-shaped or V-shaped, join distally (the exact location of the joint depends on the species) but are separated 4557:

Abzhanov, Arhat; Kuo, Winston P.; Hartmann, Christine; Grant, B. Rosemary; Grant, Peter R.; Tabin, Clifford J. (August 2006).

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Pitocchelli, Jay; John F. Piatt; Harry R. Carter (2003). "Variation in plumage, molt, and morphology of the Whiskered Auklet (

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The shape or color of the culmen can also help with the identification of birds in the field. For example, the culmen of the

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Carboneras, Carlos (1992). "Family Diomedeidae (Albatrosses)". In del Hoyo, Josep; Elliott, Andrew; Sargatal, Jordi (eds.).

900:(UV) component, with a UV peak that correlates to the bird's mass. A chick with a lower body mass has a UV peak at a higher 1212:

Color can also differ between sexes or ages within a species. Typically, such a color difference is due to the presence of

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in gull chicks. The chick pecks at the spot on its parent's bill, which in turn stimulates the parent to regurgitate food.

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are a notable exception; their nares are located at the tip of their bills. A handful of species have no external nares.

254:'s upper mandible can flex upwards because it is supported by small bones which can move slightly backwards and forwards. 884: 298: 6523: 553: 6305: 3237: 4752: 4083: 3965: 3936: 2600: 2322: 2224: 1841:

The British cyclopæedia of natural history: Combining a scientific classification of animals, plants, and minerals

728:) located somewhere on their beak. The nares are two holes—circular, oval or slit-like in shape—which lead to the 404:(seed-eating) birds, for example, have ridges in their tomia, which help the bird to slice through a seed's outer 6220: 6210: 1461: 1185: 1127: 416:, principally those that prey on insects or lizards, also have one or more of these sharp projections, as do the 5488:

Amerson, A. Binion (May 1967). "Incidence and Transfer of Rhinonyssidae (Acarina: Mesostigmata) in Sooty Terns (

5164: 6546: 6528: 2994: 2630: 1519:, which has the largest beak relative to the size of its body of any bird species, is capable of modifying the 1327:

uses its bill to navigate underwater, detect food, and dig. The bill contains receptors that help detect prey.

687: 424:, have sawtooth serrations along their tomia, which help them to keep hold of their slippery, wriggling prey. 1188:. For example, females of nearly all shorebirds have longer bills than males of the same species, and female 6551: 4854: 2402:

Hieronymus, Tobin L.; Witmer, Lawrence M. (2010). "Homology and evolution of avian compound rhamphothecae".

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to its beak. This process allows the beak to work as a "transient thermal radiator", reportedly rivaling an

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Schuetz, Justin G. (October 2005). "Reduced growth but not survival of chicks with altered gape patterns".

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routinely bill more dominant birds, lowering their body and quivering their wings in the manner of a young

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Some species use their beaks in displays of various sorts. As part of his courtship, for example, the male

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Rictal bristles are stiff hair-like feathers that arise around the base of the beak. They are common among

6518: 6330: 6280: 1418: 879:, which means "wax") or ceroma which covers the base of their bill. This structure typically contains the 581: 234:

and surrounded by the hard outer layers of the beak. The avian jaw apparatus is made up of two units: one

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Abzhanov, Arhat; Protas, Meredith; Grant, B. Rosemary; Grant, Peter R.; Tabin, Clifford J. (2004-09-03).

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Noble, D.G.; Davies, N.B.; Hartley, I.R.; McRae, S.B. (July 1999). "The Red Gape of the Nestling Cuckoo (

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Comparison of bird beaks, displaying different shapes adapted to different feeding methods. Not to scale.

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levels are lower than those found in untrimmed poultry, indicating that they are less stressed overall.

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breeder flocks, because it helps reduce the damage the flocks inflict on themselves due to a number of

6983: 5248: 4688: 4622:"Conditional inactivation of Tgfbr2 in cranial neural crest causes cleft palate and calvaria defects" 4570: 4504: 3546: 2916: 1731: 1626: 1055: 889: 94: 2085:"A new eocene Chascacocolius-like mousebird (Aves: Coliiformes) with a remarkable gaping adaptation" 2061: 1315:

threatening an intruder. Barn owl threat displays usually include hissing and bill-snapping, as here

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join together at the base of the beak. The width of the gape can be a factor in the choice of food.

6513: 6405: 6345: 6290: 6070: 2903:"Sibling competition and conspicuousness of nestling gapes in altricial birds: A comparative study" 2363:

Chernova, O.F.; Fadeeva, E.O. (2009). "The peculiar architectonics of contour feathers of the emu (

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of all ages, which also lack external nostrils) breathe through their mouths. There is typically a

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between the mandibles, thereby improving the bird's ability to hold hard prey items. Serrations on

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Nicola, Saino; Roberto, Ambrosini; Roberta, Martinelli; Paola, Ninni; Anders Pape, Møller (2003).

2877: 2715:"What Do Different Bill Measures Measure and What Is the Best Method to Use in Granivorous Birds?" 892:'s cere, for example, correlates to its body mass and physical condition. The cere color of young 451:. In some cases, the color of a bird's tomia can help to distinguish between similar species. The 7296: 6360: 6320: 6285: 5723: 5647: 5340: 5272: 5186: 4957: 4846: 4657: 4602: 4536: 4470: 4302: 4181: 4036: 3988: 3427: 3179: 3085: 2986: 2869: 2745: 2737: 2579: 2419: 2384: 2345: 2303: 2247: 1696: 1556: 1000: 893: 521: 66: 5845: 5700:

Cunningham, Susan J.; Alley, M.R.; Castro, I.; Potter, M.A.; Cunningham, M.; Pyne, M.J. (2010).

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The beak of modern birds has a fused premaxillary bone, which is modulated by the expression of

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Ash, (1960). "A study of the mallophaga of birds with particular reference to their ecology".

3380: 3268: 3262: 2060:. Society for Integrative & Comparative Biology. Charleston, South Carolina. Archived from 1139:. Colors are typically brightest as the breeding season approaches, and palest after breeding. 960:, nerve cells that are sensitive to pressure, vibration, or touch, are located under the nail. 497:(measured in a straight line from point to point, ignoring any curve in the culmen) taken with 7422: 7369: 7319: 6462: 6452: 6395: 6195: 6190: 6041: 6022: 5999: 5980: 5961: 5942: 5923: 5904: 5885: 5866: 5849: 5824: 5807: 5776: 5618: 5575: 5544: 5509: 5468: 5434: 5401: 5264: 5221: 5178: 5126: 5108: 4965: 4838: 4830: 4724: 4706: 4675:

Mallarino, R.; Grant, P. R.; Grant, B. R.; Herrel, A.; Kuo, W. P.; Abzhanov, A. (2011-03-08).

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During courtship, mated pairs of many bird species touch or clasp each other's bills. Termed

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chick still has its egg tooth, the small white projection near the tip of its upper mandible.

455:, for example, has a reddish-pink bill with black tomia, while the whole beak of the similar 7288: 6430: 6102: 5766: 5758: 5713: 5563: 5536: 5501: 5422: 5322: 5295: 5256: 5213: 5168: 5160: 5116: 5100: 5051: 4949: 4820: 4812: 4714: 4696: 4633: 4578: 4512: 4454: 4292: 4171: 4020: 3980: 3705: 3697: 3656: 3648: 3477: 3417: 3214: 3171: 3123: 3069: 3032: 3024: 2978: 2934: 2924: 2861: 2729: 2484: 2455: 2411: 2376: 2337: 2295: 2239: 2099: 2021: 1665: 1531: 1439: 1409: 1202: 1136: 1083: 1009: 976: 923: 873: 769: 667: 505: 494: 480: 448: 385: 334: 306: 235: 2964:"Coevolution, communication, and host-chick mimicry in parasitic finches: who mimics whom?" 709: 7520: 7348: 6818: 6340: 6325: 6263: 6162: 6090: 5372: 1677: 1572: 1189: 1156: 1063: 957: 823: 694:), have colored patches on the wing that mimic the gape color of the parasitized species. 592: 178:

Although the word "beak" was, in the past, generally restricted to the sharpened bills of

159: 5564: 1515:

Studies have shown that some birds use their beaks to rid themselves of excess heat. The

456: 5252: 4692: 4574: 4508: 4442: 3792: 2920: 736:. In most bird species, the nares are located in the basal third of the upper mandible. 209: 7630: 7560: 7512: 7446: 7385: 7340: 7327: 7201: 7164: 7015: 6789: 6626: 6380: 6375: 6370: 6350: 6335: 6230: 6225: 6205: 6200: 6182: 6130: 6063: 5771: 5742: 5702:"Bill morphology or Ibises suggests a remote-tactile sensory system for prey detection" 5121: 5088: 5055: 4719: 4676: 4559:"The calmodulin pathway and evolution of elongated beak morphology in Darwin's finches" 4279:

Jouventin, Pierre; Nolan, Paul M.; Örnborg, Jonas; Dobson, F. Stephen (February 2005).

3710: 3685: 3661: 3636: 3037: 3012: 2939: 2902: 1839: 1689: 1567: 1548: 1233: 908: 729: 683: 618: 444: 187: 151: 5839: 5217: 4492: 2488: 2057:

Beyond the beak: Modeling avian cranial kinesis and the evolution of bird skull shapes

1930: 7682: 7568: 7552: 7475: 7467: 7301: 7099: 6949: 6836: 6794: 6594: 6586: 6508: 6472: 6390: 6314: 6015: 5800: 5540: 5423: 5395: 5326: 5299: 4825: 4474: 4247: 3478: 3448:

The Bird: A natural history of who birds are, where they came from, and how they live

3218: 1926: 1685: 1621: 1413: 1337: 1217: 1209:'s slim, decurved bill was nearly twice as long as the male's straight, thicker one. 1043: 995: 964: 675: 623: 509: 484: 428: 179: 5977:

Collins Bird Guide: The Most Complete Field Guide to the Birds of Britain and Europe

5727: 5276: 5190: 4661: 4540: 4306: 4040: 3566: 3133: 3089: 2990: 2749: 2423: 2388: 2307: 1813: 1126:

of the color is determined by the precise mix of red and yellow pigments, while the

1020: 790: 364:

birds have a single seamless rhamphotheca, species in a few families, including the

7654: 7398: 7243: 7059: 6897: 6845: 6717: 6678: 6447: 6435: 6425: 6415: 6112: 4850: 4756: 4606: 3320:

The Birder's Handbook: A field guide to the natural history of North American birds

1771: 1739: 1704: 1673: 1357: 1319: 1221: 1152: 1115: 1074:

chicks have an egg tooth while still in the egg but lose it before hatching, while

968: 761: 733: 655: 600: 489: 108: 3073: 3011:

Hunt, Sarah; Kilner, Rebecca M.; Langmore, Naomi E.; Bennett, Andrew T.D. (2003).

1368:). Birds that fish for a living have beaks adapted for that pursuit; for example, 269: 246: 4770: 4677:"Two developmental modules establish 3D beak-shape variation in Darwin's finches" 3606: 2929: 2025: 1889: 748:

have primitive external nares as nestlings, but these close soon after the birds

7459: 7306: 7112: 7091: 7080: 7045: 6912: 6902: 6860: 6751: 6618: 6420: 6245: 6240: 6172: 6157: 6125: 5670: 2323:"Schedule of presupplemental molt of white pelicans with notes on the bill horn" 1743: 1719: 1516: 1500: 1475: 1422: 1160: 1147: 1143: 1107: 1075: 1025: 948: 915:'s cere is royal blue, while the female's is a very pale blue, white, or brown. 897: 737: 659: 648: 640: 513: 467: 440: 413: 401: 183: 124: 2733: 2685:

Pyle, Peter; Howell, Steve N. G.; Yunick, Robert P.; DeSante, David F. (1987).

1984:(2nd ed.). New York, NY: W.H. Freeman and Company. pp. 149, 427–428. 1474:

Additionally, because of the role beaks play in preening, this is evidence for

827:

as the birds age, disappearing completely by the time they reach adulthood. In

7576: 7438: 7377: 7356: 7188: 7172: 7107: 7052: 7024: 6956: 6921: 6799: 6647: 6482: 6457: 6215: 5975:

Mullarney, Killian; Svensson, Lars; Zetterström, Dan; Grant, Peter J. (1999).

5505: 5341:"Evolution of bird bills: Birds reduce their 'heating bills' in cold climates" 2982: 2571: 2380: 2299: 2103: 1613: 1535: 1520: 1373: 1365: 1225: 972: 912: 901: 591:

The gapes of juvenile altricial birds are often brightly coloured, as in this

452: 361: 350: 120: 5853: 5225: 5182: 5112: 4834: 4790: 4788: 4786: 4784: 4710: 4645: 4590: 4558: 4524: 3875: 3128: 3081: 1944: 1086:

have theirs for up to a month. Generally, the egg tooth drops off, though in

213:

The bony core of the beak is a lightweight framework, like that seen on this

7536: 7491: 7280: 7073: 6990: 6974: 6963: 6873: 6809: 6768: 6467: 6268: 6255: 6235: 6135: 5260: 4701: 4516: 3422: 3405: 3175: 1657: 1646: 1617: 1588: 1496: 1385: 1349: 1345: 1341: 1336:

Different species' beaks have evolved according to their diet; for example,

1111: 1039: 1033: 1005: 928: 811: 795: 778: 741: 717: 644: 631: 421: 365: 227: 147: 135: 112: 86: 6017:

Songs, Roars and Rituals: Communication in birds, mammals and other animals

5802:

Bird Display and Behaviour: An introduction to the study of bird psychology

5780: 5762: 5718: 5701: 5548: 5268: 5130: 5104: 4969: 4842: 4728: 4653: 4598: 4532: 4466: 4249:

Songs, Roars and Rituals: Communication in birds, mammals and other animals

4032: 3843:

Why Ducks Do That: 40 distinctive duck behaviors explained and photographed

3719: 3701: 3670: 3652: 3046: 3028: 2948: 2793:

Russell, Peter J.; Wolfe, Stephen L.; Hertz, Paul E.; Starr, Cecie (2008).

2460: 2443: 2415: 2033: 1715: 78: 74: 5513: 4193: 4176: 4159: 2475:

Klasing, Kirk C. (1999). "Avian gastrointestinal anatomy and physiology".

7504: 7234: 7209: 7155: 7066: 7038: 6928: 6892: 6884: 6866: 6761: 6746: 6730: 6477: 6440: 6273: 5089:"Adaptive significance of avian beak morphology for ectoparasite control" 3868:

Functional Anatomy of the Feeding Apparatus in Waterfowl (Aves: Anatidae)

2907: 1681: 1539: 1524: 1455: 1434: 1405: 1353: 1324: 1312: 1213: 1194: 1087: 1071: 936: 838: 636: 612: 498: 342: 214: 155: 143: 90: 4582: 1171: 1042:

projection on their beak, which they use to chip their way out of their

7414: 7267: 7146: 7031: 6997: 6935: 6756: 6610: 6602: 6295: 6167: 6152: 6142: 4961: 4354:

Identify Yourself: The 50 most common birding identification challenges

4185: 4024: 3992: 3584:(14th ed.). Pearson Benjamin Cummings Prentice Hall. p. 111. 3431: 3183: 2873: 2741: 2349: 2251: 1755: 1661: 1653: 1605: 1377: 1369: 1132: 1103: 1099: 1051: 952: 816: 725: 671: 537: 517: 318: 139: 131: 116: 70: 37: 6055: 5173: 4637: 4458: 1630:

are known to be transferred between birds during episodes of billing.

1340:

have sharp-pointed beaks that facilitate dissection and biting off of

1248:

gene in the frontonasal ectodermal zone during embryonic development.

1119:

responsible for the coloration of most red, orange, and yellow beaks.

7544: 7483: 7259: 7251: 7180: 7120: 7004: 6942: 6825: 6492: 6487: 6365: 4057:

Perrins, Christopher M.; Attenborough, David; Arlott, Norman (1987).

3105:"Gape coloration reliably reflects immunocompetence of barn swallow ( 2554:

Feeding in vertebrates: evolution, morphology, behavior, biomechanics

1751: 1601: 1597: 1544: 1079: 944: 911:

has a yellow cere, which the female (and young males) lack. The male

850: 841:

are the only birds known to have the ability to move their opercula.

828: 774: 753: 749: 745: 713: 698: 663: 417: 409: 346: 282: 128: 82: 62: 5599:. Vol. 12. New York, NY: Marshall Cavendish Corp. p. 1680. 5146:"Influence of bill shape on ectoparasite load in western scrub-jays" 4953: 3984: 3684:

Parejo, Deseada; Avilés, Jesús M.; Rodriguez, Juan (23 April 2010).

2865: 2341: 2243: 1372:' beaks are well adapted for scooping up and swallowing fish whole. 17: 4816: 4052: 4050: 3870:. Carbondale, IL: Southern Illinois University Press. p. 179. 3354:. Vol. 1: Ostrich to Ducks. Barcelona: Lynx Edicions. p. 2225:"Indentation hardness of the bill keratin of the European starling" 697:

When born, the chick's gape flanges are fleshy. As it grows into a

7430: 7217: 6780: 2631:"Serrate Tomia: An Adaptation for Nectar Robbing in Hummingbirds?" 1783: 1714: 1609: 1566: 1504: 1488: 1318: 1299: 1170: 1047: 1019: 922: 789: 757: 708: 617: 586: 466: 432: 379: 286: 274: 268: 263: 245: 208: 36: 5144:

Moyer, Brett R.; Peterson, A. Townsend; Clayton, Dale H. (2002).

5093:

Proceedings of the Royal Society of London B: Biological Sciences

4297: 4280: 2797:. Vol. 2. Belmont, CA: Thomson Brooks / Cole. p. 1255. 447:, as they can more effectively hold and cut through long or waxy 7406: 6773: 6736: 6706: 6086: 5811: 3802: 3390: 1735: 1381: 1206: 1176: 1059: 833: 435:

eaters, and the brush-like projections may help to increase the

405: 302: 259: 251: 58: 6570: 6059: 4493:"Bmp4 and Morphological Variation of Beaks in Darwin's Finches" 3902:(5 ed.). Washington, DC: National Geographic. p. 40. 2174: 2172: 2170: 2168: 2166: 2164: 2162: 2160: 2158: 341:, growing from plates at the base of each mandible. There is a 7528: 6385: 6147: 5368:"Add this to life list: 'Birding' has inspired flock of words" 4253:. Boston, MA: Harvard University Press. pp. 20, 83, 155. 3406:"Organisms as functional machines: A connectivity explanation" 3013:"Conspicuous, ultravioletrich mouth colours in begging chicks" 2901:

Soler, J.J.; Avilés, J.M. (2010). Halsey, Lewis George (ed.).

2156: 2154: 2152: 2150: 2148: 2146: 2144: 2142: 2140: 2138: 1552: 1492: 1396:

Birds may bite or stab with their beaks to defend themselves.

1123: 369: 354: 4351:

Thompson, Bill; Blom, Eirik A.T.; Gordon, Jeffrey A. (2005).

4137:. Vancouver, BC: University of Washington Press. p. 26. 1600:

raise their bills high and repeatedly clatter them, the male

4382:

O'Brien, Michael; Crossley, Richard; Karlson, Kevin (2006).

4323:

Sexual Selection and the Descent of Man: The Darwinian pivot

3385:. Vol. 6. New York: The Century Company. p. 4123. 2847:"Fruit size, gape width and the diets of fruit-eating birds" 943:, a plate of hard horny tissue at the tip of the beak. This 345:

layer between the rhamphotheca and the deeper layers of the

5570:(4 ed.). London, UK: Routledge Classics 2001. p. 5165:

10.1650/0010-5422(2002)104[0675:iobsoe]2.0.co;2

3528:. Centre for Ecology & Hydrology: 22–40. Archived from 1575:

raise their beaks high and clatter them against each other.

1460:

The beak of birds plays a role in removing skin parasites (

1446:, which assist in velocity detection while filter feeding. 1279:

is involved in the differentiation of terminal bone cells.

317:

The outer surface of the beak consists of a thin sheath of

5743:"Vision, touch and object manipulation in Senegal parrots 4798:"Reciprocal Natural Selection on Host-Parasite Phenotypes" 4420:. Vol. 2. New York, NY: Academic Press. p. 371. 3794:

The Wild Fowl of the United States and British Possessions

3686:"Visual cues and parental favouritism in a nocturnal bird" 3317:

Ehrlich, Paul R.; Dobkin, David S.; Wheye, Darryl (1998).

2762:

Mullarney, Svensson, Zetterström & Grant (1999) p. 357

2444:"The Integumentary Morphology of Modern Birds—An Overview" 1098:

The color of a bird's beak results from concentrations of

1038:

Full-term chicks of most bird species have a small sharp,

674:

led to a less vivid gape. Conversely, the red gape of the

658:

nestlings showed the vividness of the gape was positively

277:(shaded red) in neognathae (left) and paleognathae (right) 4796:

Clayton, ; Lee, ; Tompkins, ; Brodie, (September 1999).

3922:

Mullarney, Svensson, Zetterström & Grant (1999) p. 40

3199:"Yellow wing-patch of a nestling Horsfield's hawk cuckoo 3162:) is not a supernormal stimulus for three common hosts". 2771:

Mullarney, Svensson, Zetterström & Grant (1999) p. 15

1695:

A similar but separate practice, usually performed by an

1587:

in British English), this behavior appears to strengthen

5421:

Schreiber, Elizabeth Anne; Burger, Joanna, eds. (2002).

5397:

The Audubon Society Encyclopedia of North American Birds

3739:. Berkeley, CA: University of California Press. p. 1974: 1620:

begging as they do so. A number of parasites, including

1179:(female upper, male lower) show marked sexual dimorphism 4219:. Washington, DC: National Geographic. pp. 62–66. 4059:

New Generation Guide to the Birds of Britain and Europe

3567:

Webster's Unabridged Dictionary of the English Language

3267:. New Brunswick, NJ: Rutgers University Press. p. 3197:

Tanaka, Keita D.; Morimoto, Gen; Ueda, Keisuke (2005).

2502:

Ferguson-Lees, James; Christie, David A. (2001-01-01).

2005:

Seki, Yasuaki; Bodde, Sara G.; Meyers, Marc A. (2009).

1972: 1970: 1968: 1966: 1964: 1962: 1960: 1958: 1956: 1954: 1400:

Displays (for courtship, territoriality, or deterrence)

1260:, while that of the premaxillary bone is controlled by 1110:— in the epidermal layers, including the rhamphotheca. 107:

are also used to refer to a similar mouth part in some

5884:(2 ed.). New York, NY: W.H. Freeman and Company. 4936:

Boyd, (1951). "A survey of parasitism of the Staling

4061:. Austin, TX: University of Texas Press. p. 205. 1707:

keepers, this practice is commonly known as "coping".

1412:

on his wings in a fake preening display, and the male

1348:

birds that specialize in eating seeds with especially

483:

ridge of the upper mandible. Likened by ornithologist

5608: 5606: 5467:. Boston, MA: Harvard University Press. p. 227. 4326:. New Brunswick, NJ: Transaction Publishers. p. 4240: 4238: 4236: 3964:

Conover, Michael R.; Miller, Don E. (November 1980).

3635:

Mougeo, François; Arroyo, Beatriz E. (22 June 2006).

3379:

Whitney, William Dwight; Smith, Benjamin Eli (1911).

2713:

Borras, A.; Pascual, J.; Senar, J. C. (Autumn 2000).

1722:

have a probing bill that allows them to detect motion

1530:

Measurements of the bill sizes of several species of

732:

within the bird's skull, and thus to the rest of the

682:) did not induce extra feeding in host parents. Some 647:

species found that the gapes were conspicuous in the

607:

is the interior of the open mouth of a bird, and the

508:

is strongly decurved, while that of the very similar

333:

of the lower mandible. This covering arises from the

5956:

King, Anthony Stuart; McLelland, John, eds. (1985).

3484:. Collingwood, Victoria: Csiro Publishing. pp. 1868:. New Haven, CT: Yale University Press. p. 66. 1859: 1857: 1855: 512:

is more moderately curved. The culmen of a juvenile

57:

is an external anatomical structure found mostly in

7503: 7458: 7397: 7368: 7339: 7318: 7279: 7242: 7233: 7200: 7163: 7154: 7145: 7090: 7014: 6973: 6911: 6883: 6859: 6835: 6808: 6729: 6716: 6677: 6646: 6585: 6501: 6404: 6304: 6254: 6181: 6111: 5996:

Manual of Ornithology: Avian Structure and Function

5865:(4 ed.). New York, NY: McGraw Hill Companies. 5741:Demery, Zoe P.; Chappell, J.; Martin, G.R. (2011). 5529:

The Journal of the Australia Veterinary Association

4357:. New York, NY: Houghton Mifflin Harcourt. p. 4112:. Washington, DC: National Geographic. p. 23. 3866:Goodman, Donald Charles; Fisher, Harvey I. (1962). 3294:

White-tailed ptarmigan: Ghosts of the alpine tundra

1866:

Manual of Ornithology: Avian structure and function

670:, and that larger brood size and injection with an 258:The upper mandible is supported by a three-pronged 6014: 5799: 4246: 2659:. London, UK: Christopher Helm. pp. 143–144. 967:has a wider black nail than does the very similar 3203:induces miscognition by hosts: Mimicking a gape?" 1467:This overhang of the beak is thought to be under 5001:Worth, (1940). "A note on the dissemination of 4281:"Ultraviolet spots in king and emperor penguins" 3845:. Minocqua, WI: Willow Creek Press. p. 31. 3637:"Ultraviolet reflectance by the cere of raptors" 2689:. Bolinas, CA: Slate Creek Press. pp. 6–7. 2687:Identification Guide to North America Passerines 2605:: An adaptation for handling hard-shelled prey?" 2271:. London, UK: Longmans, Green and Co. p. 5. 2007:"Toucan and hornbill beaks: A comparative study" 1364:power (on the same principle as a human-devised 1220:, melanins are produced only in the presence of 626:is the yellowish region at the base of the beak. 552:near the gonydeal expansion. This spot triggers 5819:Campbell, Bruce; Lack, Elizabeth, eds. (1985). 4681:Proceedings of the National Academy of Sciences 4209: 4207: 4205: 4203: 4110:National Geographic Complete Birds of the World 3898:Dunn, Jon L.; Alderfer, Jonathan, eds. (2006). 2180:Campbell, Bruce; Lack, Elizabeth, eds. (1985). 1637:time, and derives from the courtship of doves. 798:'s operculum is a mass at the base of the bill. 388:'s bill help it to hold tight to its fish prey. 5615:Improving Animal Welfare: A practical approach 4755:. Biology 342: Animal Behavior. Portland, OR: 4386:. New York, NY: Houghton Mifflin. p. 76. 3966:"Rictal Bristle Function in Willow Flycatcher" 3736:Wildlife of Mexico: The Game Birds and Mammals 2437: 2435: 2433: 516:is all dark, while that of the very similarly 238:mechanism and one five-bar linkage mechanism. 6071: 6013:Rogers, Lesley J.; Kaplan, Gisela T. (2000). 5994:Proctor, Noble S.; Lynch, Patrick J. (1998). 4245:Rogers, Lesley J.; Kaplan, Gisela T. (2000). 4084:"Occurrence and timing of egg teeth in birds" 4006: 4004: 4002: 3797:. New York, NY: F. P. Harper. p. xviii. 2962:Hauber, Mark & Rebecca M. Kilner (2007). 1864:Proctor, Noble S.; Lynch, Patrick J. (1998). 1050:, as the similarly-named projections of some 822:help to keep dust out. The nares of nestling 8: 5068:: CS1 maint: multiple names: authors list ( 5023:: CS1 maint: multiple names: authors list ( 4982:: CS1 maint: multiple names: authors list ( 4877:: CS1 maint: multiple names: authors list ( 4274: 4272: 4270: 3323:. New York, NY: Simon and Schuster. p. 3256: 3254: 2531:. London, UK: Christopher Helm. p. 15. 2506:. London, UK: Christopher Helm. p. 66. 1920: 1918: 1916: 1914: 1912: 1910: 5960:. Vol. 3. London, UK: Academic Press. 3296:. Boulder, CO: Johnson Books. p. 110. 2779: 2777: 861:"Cere" redirects here. For other uses, see 724:Most species of birds have external nares ( 576:"Gape" redirects here. For other uses, see 7239: 7160: 7151: 7142: 6880: 6726: 6713: 6674: 6670: 6643: 6582: 6578: 6567: 6563: 6078: 6064: 6056: 5941:. New York, NY: Houghton Mifflin Company. 5072:) CS1 maint: numeric names: authors list ( 5027:) CS1 maint: numeric names: authors list ( 4986:) CS1 maint: numeric names: authors list ( 4881:) CS1 maint: numeric names: authors list ( 3959: 3957: 3930: 3928: 3451:. New York, NY: Crown Publishers. p. 2584:: CS1 maint: location missing publisher ( 1786: – Extended part of an animal's mouth 883:, except in the owls, where the nares are 802:The nares of some birds are covered by an 5841:Handbook of Field and General Ornithology 5770: 5717: 5640:"Bird Beaks: Anatomy, care, and diseases" 5172: 5120: 4824: 4718: 4700: 4296: 4175: 3900:Field Guide to the Birds of North America 3786: 3784: 3709: 3660: 3630: 3628: 3421: 3127: 3036: 2938: 2928: 2708: 2706: 2552:V. L. Bels; Ian Q. Whishaw, eds. (2019). 2477:Seminars in Avian and Exotic Pet Medicine 2459: 2268:The structure and classification of birds 1935:. London, UK: Macmillan and Co. pp. 1932:Handbook of Field and General Ornithology 6021:. Boston, MA: Harvard University Press. 5998:. New Haven, CT: Yale University Press. 5844:. London, UK: Macmillan and Co. p. 5595:Burton, Maurice; Burton, Robert (1980). 3608:Parrots: A Guide to Parrots of the World 3261:Capainolo, Peter; Butler, Carol (2010). 2223:Bonser, R.H. & Witter, M.S. (1993). 2121:. Vancouver, BC: UBC Press. p. 19. 1608:puts his bill in the female's mouth and 1201:in the size and shape of both beaks and 5922:. Washington, DC: National Geographic. 5823:. Carlton, England: T and A.D. Poyser. 5597:The International Wildlife Encyclopedia 4082:Clark, George A. Jr. (September 1961). 2680: 2678: 2676: 2184:. Carlton, England: T and A.D. Poyser. 1830: 1796: 1604:nibbles at the female's beak, the male 1082:keep theirs for nearly three weeks and 5617:. Oxfordshire, UK: CABI. p. 110. 5061: 5016: 4975: 4870: 2577: 1838:Partington, Charles Frederick (1835). 459:is pinkish-red, without darker tomia. 69:and a few mammals. A beak is used for 5429:. Boca Raton, FL: CRC Press. p. 4552: 4550: 4486: 4484: 4320:Campbell, Bernard Grant, ed. (1972). 4135:The Inner Bird: Anatomy and evolution 3382:The Century Dictionary and Cyclopedia 2119:The Inner Bird: Anatomy and Evolution 1527:in its ability to radiate body heat. 1442:. The beaks of aquatic birds contain 197:), which itself comes from the Latin 146:, which have a beak-like structure), 85:, manipulating and carrying objects, 7: 7637: 5903:. Oxford, UK: Blackwell Publishing. 5806:. New York, NY: Dover Publications. 5798:Armstrong, Edward Allworthy (1965). 2527:Harris, Tony; Franklin, Kim (2000). 2092:Organisms, Diversity & Evolution 1360:) have large, stout beaks with high 349:, which is attached directly to the 7661: 5920:National Geographic Bird Coloration 4217:National Geographic Bird Coloration 3937:"The Role of Avian Rictal Bristles" 3820:. London, UK: Collins. p. 24. 2655:Madge, Steve; Burn, Hilary (1988). 2448:Integrative and Comparative Biology 325:, which can be subdivided into the 5751:Proceedings of the Royal Society B 5056:10.1111/j.1474-919X.1960.tb05095.x 3888:King & McLelland (1985) p. 421 3778:King & McLelland (1985) p. 376 3605:Jupiter, Tony; Parr, Mike (2010). 927:The nail is the black tip of this 431:(preferring hard-shelled prey) or 25: 6539:Late Quaternary prehistoric birds 5901:Veterinary Nursing of Exotic Pets 5400:. New York, NY: Alfred A. Knopf. 5366:Bierma, Nathan (12 August 2004). 5218:10.1034/j.1600-0706.2001.940308.x 3581:Henderson's Dictionary of Biology 1759: 1384:while hunting for their meals of 939:(ducks, geese, and swans) have a 837:, this is a different structure. 622:The gape flange on this juvenile 7660: 7648: 7636: 7625: 7624: 7515:(New World vultures and condors) 5541:10.1111/j.1751-0813.2010.00681.x 5300:10.1111/j.1600-0587.2011.07002.x 3816:Perrins, Christopher M. (1974). 3219:10.1111/j.2005.0908-8857.03439.x 2599:Gosner, Kenneth L. (June 1993). 1054:are; instead, it is part of the 170:lead to the respiratory system. 5681:from the original on 2005-04-06 4896:Pomeroy, D.E. (February 1962). 4160:"The Control of Color in Birds" 3766:A Birdkeeper's Guide to Budgies 1816:. 1891 – via Archive.org. 1487:A number of species, including 752:; adults of these species (and 97:, and feeding young. The terms 5979:. London, UK: Harper Collins. 4158:Ralph, Charles L. (May 1969). 3791:Elliot, Daniel Giraud (1898). 3733:Leopold, Aldo Starker (1972). 3351:Handbook of Birds of the World 2442:Stettenheim, Peter R. (2000). 1668:-induced behaviors, including 329:of the upper mandible and the 1: 5494:Journal of Medical Entomology 5294:. online first (2): 146–152. 3611:. A&C Black. p. 17. 3074:10.1016/j.anbehav.2005.01.007 2489:10.1016/S1055-937X(99)80036-X 1688:weigh less, and their plasma 1469:stabilising natural selection 1408:touches his beak to the blue 1175:The beaks of the now-extinct 384:The sawtooth serrations on a 226:network of bony spicules (or 5937:Howell, Steve N. G. (2007). 5327:10.1016/0306-4565(94)90042-6 2930:10.1371/journal.pone.0010509 2795:Biology: The Dynamic Science 2722:Journal of Field Ornithology 2288:Journal of Field Ornithology 2054:Olsen, A.M. (3–7 Jan 2012). 2026:10.1016/j.actbio.2009.08.026 1376:have beaks well adapted for 611:is the region where the two 305:, which have well-developed 7579:(woodpeckers and relatives) 6036:Samour, Jaime, ed. (2000). 4898:"Birds with abnormal bills" 4753:"Platypus electroreception" 3264:How Fast Can a Falcon Dive? 2818:Newman, Kenneth B. (2000). 2369:Doklady Biological Sciences 1844:. Orr & Smith. p. 1738:, shorebirds of the family 1008:). Studies have shown that 810:), a membraneous, horny or 7705: 7441:(cormorants and relatives) 6534:Extinct species since 1500 5958:Form and Function in Birds 5918:Hill, Geoffrey E. (2010). 5861:Gilbertson, Lance (1999). 5638:Race Foster; Marty Smith. 5463:Wilson, Edward O. (1980). 5315:Journal of Thermal Biology 4911:(2): 49–72. Archived from 4751:Patel, Meera (Fall 2007). 4215:Hill, Geoffrey E. (2010). 3768:. Tetra Press. p. 12. 3476:Kaplan, Gisela T. (2007). 2845:Wheelwright, N.T. (1985). 2734:10.1648/0273-8570-71.4.606 2265:Beddard, Frank E. (1898). 1644: 1453: 1031: 880: 860: 849:Some species, such as the 768:Species in the bird order 575: 29: 7620: 7571:(kingfishers and rollers) 7425:(albatrosses and petrels) 7309:(swifts and hummingbirds) 7291:(nightjars and relatives) 7141: 7115:(pheasants and relatives) 6673: 6642: 6581: 6577: 6566: 6562: 6098: 4108:Harris, Tim, ed. (2009). 3578:Eleanor Lawrence (2008). 2983:10.1007/s00265-006-0291-0 2629:Ornelas, Juan Francisco. 2381:10.1134/S0012496609020264 2300:10.1648/0273-8570-74.1.90 2104:10.1016/j.ode.2004.10.013 1186:intraspecific competition 524:is pale towards the tip. 7470:(seriemas and relatives) 7449:(pelicans and relatives) 5613:Grandin, Temple (2010). 5562:Partridge, Eric (2001). 5394:Terres, John K. (1980). 4133:Kaiser, Gary W. (2007). 3764:Alderton, David (1996). 3511:"Aging Atlantic puffins 3509:Harris, Mike P. (2014). 3404:Bock, Walter J. (1989). 3292:Gellhorn, Joyce (2007). 3238:"Backyard Mystery Birds" 3207:Journal of Avian Biology 2821:Newman's birds by colour 2529:Shrikes and Bush-Shrikes 2365:Dromaius novaehollandiae 2117:Kaiser, Gary W. (2007). 1774: – Anatomy of birds 1483:Communicative percussion 935:All birds of the family 222:internally by a complex 7563:(hornbills and hoopoes) 7478:(falcons and relatives) 5899:Girling, Simon (2003). 5880:Gill, Frank B. (1995). 5838:Coues, Elliott (1890). 5506:10.1093/jmedent/4.2.197 5425:Biology of Marine Birds 5261:10.1126/science.1175553 4942:Journal of Parasitology 4805:The American Naturalist 4777:. 4 August 2014. 27572. 4702:10.1073/pnas.1011480108 4517:10.1126/science.1098095 3240:. Bird Watcher's Digest 3176:10.1163/156853999501559 1980:Gill, Frank B. (1995). 1811:, etc. with images see 1419:Red-bellied woodpeckers 578:gaping (disambiguation) 437:coefficient of friction 7547:(trogons and quetzals) 7359:(cranes and relatives) 6629:(emus and cassowaries) 6519:Glossary of bird terms 6331:Confuciusornithiformes 5763:10.1098/rspb.2011.0374 5719:10.1525/auk.2009.09117 5105:10.1098/rspb.2004.3036 4940:L. in North America". 3841:Petrie, Chuck (2006). 3702:10.1098/rsbl.2009.0769 3653:10.1098/rsbl.2005.0434 3556:(factsheet). May 2011. 3547:"Skomer Island Puffin" 3129:10.1093/beheco/14.1.16 3029:10.1098/rsbl.2003.0009 3023:(Suppl 1): S‑25–S‑28. 2971:Behav. Ecol. Sociobiol 2824:. Struik. p. 14. 2416:10.1525/auk.2010.09122 2367:, Struthioniformes)". 2213:Samour (2000), p. 296. 1814:"Catalogue of Species" 1803:For an explanation of 1723: 1576: 1392:Self-defensive pecking 1328: 1316: 1180: 1029: 932: 799: 721: 627: 596: 582:gapes (disambiguation) 564:Depending on its use, 490:bird banding (ringing) 472: 389: 278: 255: 218: 42: 7388:(kagu and sunbittern) 7351:(gulls and relatives) 6356:Songlingornithiformes 6321:Omnivoropterygiformes 6040:. London, UK: Mosby. 5939:Gulls of the Americas 5821:A Dictionary of Birds 5745:Poicephalus senegalus 5675:The Modern Apprentice 5453:Armstrong (1965) p. 7 4826:10536/DRO/DU:30056229 4418:Vitamins and hormones 4013:Journal of Morphology 3554:www.welshwildlife.org 3515:in summer and winter" 3445:Tudge, Colin (2009). 3423:10.1093/icb/29.3.1119 2783:Howell (2007), p. 23. 2556:. Cham, Switzerland. 2204:Girling (2003), p. 4. 2182:A Dictionary of Birds 2083:Mayr, Gerald (2005). 1939:, 147, 151–152, 155. 1718: 1656:flocks, particularly 1570: 1322: 1310: 1174: 1142:Birds are capable of 1023: 982:, meaning "nail" and 926: 863:Cere (disambiguation) 793: 712: 688:Hodgson's hawk-cuckoo 621: 590: 470: 383: 272: 249: 212: 40: 32:Beak (disambiguation) 7689:Parts of a bird beak 7210:Phoenicopteriformes 5671:"Coping your Raptor" 5669:Ash, Lydia (2020) . 2504:Raptors of the World 2461:10.1093/icb/40.4.461 2321:Knopf, F.L. (1974). 1780: – Anatomy term 1732:corpuscles of Herbst 1627:Trichomonas gallinae 1056:integumentary system 777:, have a small bony 30:For other uses, see 7181:Mesitornithiformes 7175:(doves and pigeons) 6509:Families and orders 6371:Ichthyornithiformes 6346:Patagopterygiformes 5757:(1725): 3687–3693. 5566:Shakespeare's bawdy 5253:2009Sci...325..468T 4693:2011PNAS..108.4057M 4583:10.1038/nature04843 4575:2006Natur.442..563A 4509:2004Sci...305.1462A 4503:(5689): 1462–1465. 4406:Howell (2007) p. 21 4384:The Shorebird Guide 4177:10.1093/icb/9.2.521 4091:The Wilson Bulletin 3944:The Wilson Bulletin 3236:Zickefoose, Julie. 2921:2010PLoSO...510509S 2612:The Wilson Bulletin 894:Eurasian scops-owls 67:non-avian dinosaurs 7523:(eagles and hawks) 7423:Procellariiformes 7328:Opisthocomiformes 7297:Steatornithiformes 6524:List by population 6361:Hongshanornithidae 6286:Evolution of birds 5863:Zoology Lab Manual 4741:Samour (2000) p. 7 4164:American Zoologist 4025:10.1002/jmor.10908 3935:Lederer, Roger J. 3513:Fratercula arctica 3410:American Zoologist 3116:Behavioral Ecology 2014:Acta Biomaterialia 1724: 1697:avian veterinarian 1577: 1557:southern cassowary 1444:Grandry corpuscles 1344:' tissue, whereas 1329: 1317: 1230:black-headed gulls 1216:. For example, in 1181: 1030: 1001:empirical evidence 986:, meaning "beak". 951:use theirs to pry 933: 800: 734:respiratory system 722: 720:within each naris. 630:Gapes of juvenile 628: 597: 546:gonydeal expansion 522:yellow-billed loon 495:chord measurements 473: 390: 279: 256: 219: 77:, and holding (in 43: 7676: 7675: 7616: 7615: 7612: 7611: 7608: 7607: 7604: 7603: 7600: 7599: 7596: 7595: 7592: 7591: 7588: 7587: 7409:(loons or divers) 7378:Phaethontiformes 7370:Phaethontimorphae 7320:Opisthocomiformes 7289:Caprimulgiformes 7229: 7228: 7218:Podicipediformes 7137: 7136: 7133: 7132: 7129: 7128: 6855: 6854: 6638: 6637: 6595:Struthioniformes 6463:Waterfowl hunting 6396:Gastornithiformes 6391:Aepyornithiformes 6381:Lithornithiformes 6047:978-0-7234-2960-9 6028:978-0-674-00827-4 6005:978-0-300-07619-6 5986:978-0-00-711332-3 5967:978-0-12-407503-0 5948:978-0-618-72641-7 5929:978-1-4262-0571-2 5910:978-1-4051-0747-1 5891:978-0-7167-2415-5 5872:978-0-07-237716-3 5830:978-0-85661-039-4 5624:978-1-84593-541-2 5581:978-0-415-25553-0 5474:978-0-674-81624-4 5440:978-0-8493-9882-7 5407:978-0-394-46651-4 5247:(5949): 468–470. 5099:(1565): 811–817. 4687:(10): 4057–4062. 4638:10.1242/dev.00708 4632:(21): 5269–5280. 4569:(7102): 563–567. 4459:10.1111/evo.12684 4427:978-0-12-709802-9 4393:978-0-618-43294-3 4368:978-0-618-51469-4 4337:978-0-202-02005-1 4260:978-0-674-00827-4 4226:978-1-4262-0571-2 4144:978-0-7748-1344-0 4119:978-1-4262-0403-6 4068:978-0-292-75532-1 3909:978-0-7922-5314-3 3852:978-1-59543-050-2 3827:978-0-00-212173-6 3750:978-0-520-00724-6 3618:978-1-4081-3575-4 3591:978-0-321-50579-8 3535:on June 11, 2016. 3495:978-0-643-09239-6 3462:978-0-307-34204-1 3365:978-84-87334-10-8 3334:978-0-671-65989-9 3303:978-1-55566-397-1 3278:978-0-8135-4790-9 2831:978-1-86872-448-2 2804:978-0-495-01033-3 2696:978-0-9618940-0-9 2666:978-0-7470-2201-5 2563:978-3-030-13739-7 2538:978-0-7136-3861-5 2513:978-0-7136-8026-3 2191:978-0-85661-039-4 2128:978-0-7748-1343-3 1991:978-0-7167-2415-5 1875:978-0-300-07619-6 1778:Rostrum (anatomy) 1532:American sparrows 1429:Sensory detection 1410:speculum feathers 1308: 1205:, and the female 1199:sexual dimorphism 1084:marbled murrelets 1010:Herbst corpuscles 890:Montagu's harrier 307:digastric muscles 232:connective tissue 230:) seated in soft 224:three-dimensional 16:(Redirected from 7696: 7664: 7663: 7652: 7640: 7639: 7628: 7627: 7580: 7572: 7564: 7556: 7553:Leptosomiformes 7548: 7540: 7532: 7524: 7521:Accipitriformes 7516: 7495: 7494:(perching birds) 7487: 7479: 7471: 7450: 7442: 7434: 7426: 7418: 7415:Sphenisciformes 7410: 7389: 7381: 7360: 7352: 7349:Charadriiformes 7331: 7310: 7292: 7271: 7263: 7260:Musophagiformes 7255: 7240: 7221: 7213: 7192: 7184: 7176: 7161: 7152: 7143: 7116: 7103: 6881: 6877: 6870: 6783: 6776: 6740: 6727: 6723: 6714: 6710: 6675: 6671: 6644: 6630: 6622: 6614: 6606: 6598: 6583: 6579: 6568: 6564: 6431:Bird collections 6386:Dinornithiformes 6291:Darwin's finches 6281:Origin of flight 6221:Seabird breeding 6211:Sexual selection 6080: 6073: 6066: 6057: 6051: 6032: 6020: 6009: 5990: 5971: 5952: 5933: 5914: 5895: 5876: 5857: 5834: 5815: 5805: 5785: 5784: 5774: 5738: 5732: 5731: 5721: 5697: 5691: 5690: 5688: 5686: 5666: 5660: 5659: 5657: 5655: 5646:. Archived from 5635: 5629: 5628: 5610: 5601: 5600: 5592: 5586: 5585: 5569: 5559: 5553: 5552: 5524: 5518: 5517: 5485: 5479: 5478: 5460: 5454: 5451: 5445: 5444: 5428: 5418: 5412: 5411: 5391: 5385: 5384: 5382: 5380: 5363: 5357: 5356: 5354: 5352: 5337: 5331: 5330: 5310: 5304: 5303: 5287: 5281: 5280: 5236: 5230: 5229: 5201: 5195: 5194: 5176: 5150: 5141: 5135: 5134: 5124: 5084: 5078: 5077: 5067: 5059: 5039: 5033: 5032: 5022: 5014: 4998: 4992: 4991: 4981: 4973: 4938:Sturnus vulgaris 4933: 4927: 4926: 4924: 4923: 4917: 4902: 4893: 4887: 4886: 4876: 4868: 4866: 4865: 4859: 4853:. Archived from 4828: 4802: 4792: 4779: 4778: 4767: 4761: 4760: 4748: 4742: 4739: 4733: 4732: 4722: 4704: 4672: 4666: 4665: 4617: 4611: 4610: 4554: 4545: 4544: 4488: 4479: 4478: 4453:(7): 1665–1677. 4438: 4432: 4431: 4413: 4407: 4404: 4398: 4397: 4379: 4373: 4372: 4348: 4342: 4341: 4317: 4311: 4310: 4300: 4276: 4265: 4264: 4252: 4242: 4231: 4230: 4211: 4198: 4197: 4179: 4155: 4149: 4148: 4130: 4124: 4123: 4105: 4099: 4098: 4088: 4079: 4073: 4072: 4054: 4045: 4044: 4008: 3997: 3996: 3970: 3961: 3952: 3951: 3941: 3932: 3923: 3920: 3914: 3913: 3895: 3889: 3886: 3880: 3879: 3863: 3857: 3856: 3838: 3832: 3831: 3813: 3807: 3806: 3788: 3779: 3776: 3770: 3769: 3761: 3755: 3754: 3730: 3724: 3723: 3713: 3681: 3675: 3674: 3664: 3632: 3623: 3622: 3602: 3596: 3595: 3575: 3569: 3564: 3558: 3557: 3551: 3543: 3537: 3536: 3534: 3519: 3506: 3500: 3499: 3483: 3473: 3467: 3466: 3442: 3436: 3435: 3425: 3416:(3): 1119–1132. 3401: 3395: 3394: 3376: 3370: 3369: 3345: 3339: 3338: 3314: 3308: 3307: 3289: 3283: 3282: 3258: 3249: 3248: 3246: 3245: 3233: 3227: 3226: 3221:. Archived from 3194: 3188: 3187: 3155: 3149: 3148: 3146: 3144: 3138: 3132:. Archived from 3131: 3113: 3100: 3094: 3093: 3062:Animal Behaviour 3057: 3051: 3050: 3040: 3008: 3002: 3001: 2999: 2993:. Archived from 2968: 2959: 2953: 2952: 2942: 2932: 2898: 2892: 2891: 2889: 2888: 2882: 2876:. Archived from 2851: 2842: 2836: 2835: 2815: 2809: 2808: 2790: 2784: 2781: 2772: 2769: 2763: 2760: 2754: 2753: 2719: 2710: 2701: 2700: 2682: 2671: 2670: 2652: 2646: 2645: 2635: 2626: 2620: 2619: 2609: 2596: 2590: 2589: 2583: 2575: 2549: 2543: 2542: 2524: 2518: 2517: 2499: 2493: 2492: 2472: 2466: 2465: 2463: 2439: 2428: 2427: 2399: 2393: 2392: 2360: 2354: 2353: 2327: 2318: 2312: 2311: 2279: 2273: 2272: 2262: 2256: 2255: 2229: 2220: 2214: 2211: 2205: 2202: 2196: 2195: 2176: 2133: 2132: 2114: 2108: 2107: 2089: 2080: 2074: 2073: 2071: 2069: 2051: 2045: 2044: 2042: 2036:. Archived from 2011: 2002: 1996: 1995: 1976: 1949: 1948: 1922: 1905: 1904: 1902: 1900: 1886: 1880: 1879: 1861: 1850: 1849: 1835: 1819: 1817: 1801: 1573:northern gannets 1547:, including the 1440:electroreception 1352:shells (such as 1309: 1190:American avocets 1157:emperor penguins 1090:it is resorbed. 958:mechanoreceptors 824:tawny frogmouths 770:Procellariformes 668:immunocompetence 554:begging behavior 506:parrot crossbill 386:common merganser 335:Malpighian layer 236:four-bar linkage 89:, or fighting), 21: 7704: 7703: 7699: 7698: 7697: 7695: 7694: 7693: 7679: 7678: 7677: 7672: 7584: 7578: 7570: 7562: 7561:Bucerotiformes 7555:(cuckoo-roller) 7554: 7546: 7538: 7530: 7522: 7514: 7513:Cathartiformes 7499: 7493: 7485: 7484:Psittaciformes 7477: 7469: 7454: 7448: 7447:Pelecaniformes 7440: 7432: 7424: 7416: 7408: 7393: 7387: 7386:Eurypygiformes 7379: 7364: 7358: 7350: 7335: 7329: 7314: 7308: 7290: 7275: 7269: 7261: 7253: 7225: 7219: 7211: 7196: 7190: 7189:Pterocliformes 7182: 7174: 7125: 7114: 7101: 7086: 7010: 6969: 6907: 6872: 6871: 6864: 6863: 6851: 6831: 6804: 6781: 6774: 6734: 6733: 6721: 6720: 6704: 6703: 6700: 6698: 6696: 6694: 6692: 6690: 6688: 6686: 6684: 6682: 6680: 6665: 6663: 6661: 6659: 6657: 6655: 6653: 6651: 6649: 6634: 6628: 6627:Casuariiformes 6620: 6619:Apterygiformes 6612: 6604: 6596: 6573: 6558: 6529:Lists by region 6497: 6407: 6400: 6341:Chaoyangiformes 6326:Jeholornithidae 6300: 6264:Origin of birds 6250: 6231:Brood parasites 6177: 6107: 6094: 6084: 6054: 6048: 6035: 6029: 6012: 6006: 5993: 5987: 5974: 5968: 5955: 5949: 5936: 5930: 5917: 5911: 5898: 5892: 5879: 5873: 5860: 5837: 5831: 5818: 5797: 5793: 5788: 5740: 5739: 5735: 5699: 5698: 5694: 5684: 5682: 5668: 5667: 5663: 5653: 5651: 5637: 5636: 5632: 5625: 5612: 5611: 5604: 5594: 5593: 5589: 5582: 5561: 5560: 5556: 5526: 5525: 5521: 5487: 5486: 5482: 5475: 5462: 5461: 5457: 5452: 5448: 5441: 5420: 5419: 5415: 5408: 5393: 5392: 5388: 5378: 5376: 5373:Chicago Tribune 5365: 5364: 5360: 5350: 5348: 5339: 5338: 5334: 5312: 5311: 5307: 5289: 5288: 5284: 5238: 5237: 5233: 5203: 5202: 5198: 5148: 5143: 5142: 5138: 5086: 5085: 5081: 5060: 5041: 5040: 5036: 5015: 5000: 4999: 4995: 4974: 4954:10.2307/3273522 4935: 4934: 4930: 4921: 4919: 4915: 4900: 4895: 4894: 4890: 4869: 4863: 4861: 4857: 4800: 4795: 4794: 4793: 4782: 4769: 4768: 4764: 4750: 4749: 4745: 4740: 4736: 4674: 4673: 4669: 4619: 4618: 4614: 4556: 4555: 4548: 4490: 4489: 4482: 4440: 4439: 4435: 4428: 4415: 4414: 4410: 4405: 4401: 4394: 4381: 4380: 4376: 4369: 4350: 4349: 4345: 4338: 4319: 4318: 4314: 4278: 4277: 4268: 4261: 4244: 4243: 4234: 4227: 4214: 4213: 4212: 4201: 4157: 4156: 4152: 4145: 4132: 4131: 4127: 4120: 4107: 4106: 4102: 4086: 4081: 4080: 4076: 4069: 4056: 4055: 4048: 4010: 4009: 4000: 3985:10.2307/1367580 3968: 3963: 3962: 3955: 3939: 3934: 3933: 3926: 3921: 3917: 3910: 3897: 3896: 3892: 3887: 3883: 3865: 3864: 3860: 3853: 3840: 3839: 3835: 3828: 3815: 3814: 3810: 3790: 3789: 3782: 3777: 3773: 3763: 3762: 3758: 3751: 3732: 3731: 3727: 3690:Biology Letters 3683: 3682: 3678: 3641:Biology Letters 3634: 3633: 3626: 3619: 3604: 3603: 3599: 3592: 3577: 3576: 3572: 3565: 3561: 3549: 3545: 3544: 3540: 3532: 3517: 3508: 3507: 3503: 3496: 3480:Tawny Frogmouth 3475: 3474: 3470: 3463: 3444: 3443: 3439: 3403: 3402: 3398: 3378: 3377: 3373: 3366: 3347: 3346: 3342: 3335: 3316: 3315: 3311: 3304: 3291: 3290: 3286: 3279: 3260: 3259: 3252: 3243: 3241: 3235: 3234: 3230: 3196: 3195: 3191: 3160:Cuculus canorus 3157: 3156: 3152: 3142: 3140: 3139:on 11 July 2011 3136: 3111: 3107:Hirundo rustica 3102: 3101: 3097: 3059: 3058: 3054: 3017:Biology Letters 3010: 3009: 3005: 2997: 2966: 2961: 2960: 2956: 2900: 2899: 2895: 2886: 2884: 2880: 2866:10.2307/1940542 2849: 2844: 2843: 2839: 2832: 2817: 2816: 2812: 2805: 2792: 2791: 2787: 2782: 2775: 2770: 2766: 2761: 2757: 2717: 2712: 2711: 2704: 2697: 2684: 2683: 2674: 2667: 2654: 2653: 2649: 2633: 2628: 2627: 2623: 2607: 2598: 2597: 2593: 2576: 2564: 2551: 2550: 2546: 2539: 2526: 2525: 2521: 2514: 2501: 2500: 2496: 2474: 2473: 2469: 2441: 2440: 2431: 2401: 2400: 2396: 2362: 2361: 2357: 2342:10.2307/1366249 2325: 2320: 2319: 2315: 2281: 2280: 2276: 2264: 2263: 2259: 2244:10.2307/1369622 2227: 2222: 2221: 2217: 2212: 2208: 2203: 2199: 2192: 2179: 2178: 2177: 2136: 2129: 2116: 2115: 2111: 2087: 2082: 2081: 2077: 2067: 2065: 2064:on 4 March 2016 2053: 2052: 2048: 2040: 2009: 2004: 2003: 1999: 1992: 1979: 1978: 1977: 1952: 1925: 1924: 1923: 1908: 1898: 1896: 1894:Merriam-Webster 1888: 1887: 1883: 1876: 1863: 1862: 1853: 1837: 1836: 1832: 1828: 1823: 1822: 1812: 1809:aegithognathous 1802: 1798: 1793: 1768: 1713: 1678:feather pecking 1649: 1643: 1565: 1525:elephant's ears 1513: 1485: 1458: 1452: 1431: 1402: 1394: 1334: 1300: 1298: 1242: 1234:indigo buntings 1169: 1096: 1036: 1018: 992: 990:Rictal bristles 921: 866: 859: 847: 788: 707: 684:brood parasites 680:Cuculus canorus 593:common starling 585: 574: 562: 530: 465: 449:flower corollas 378: 315: 244: 207: 176: 35: 28: 23: 22: 15: 12: 11: 5: 7702: 7700: 7692: 7691: 7681: 7680: 7674: 7673: 7671: 7670: 7658: 7646: 7634: 7621: 7618: 7617: 7614: 7613: 7610: 7609: 7606: 7605: 7602: 7601: 7598: 7597: 7594: 7593: 7590: 7589: 7586: 7585: 7583: 7582: 7574: 7569:Coraciiformes 7566: 7558: 7550: 7545:Trogoniformes 7542: 7534: 7526: 7518: 7509: 7507: 7501: 7500: 7498: 7497: 7492:Passeriformes 7489: 7481: 7476:Falconiformes 7473: 7468:Cariamiformes 7464: 7462: 7456: 7455: 7453: 7452: 7444: 7436: 7431:Ciconiiformes 7428: 7420: 7412: 7403: 7401: 7395: 7394: 7392: 7391: 7383: 7374: 7372: 7366: 7365: 7363: 7362: 7354: 7345: 7343: 7341:Cursorimorphae 7337: 7336: 7334: 7333: 7324: 7322: 7316: 7315: 7313: 7312: 7304: 7299: 7294: 7285: 7283: 7277: 7276: 7274: 7273: 7265: 7257: 7248: 7246: 7237: 7231: 7230: 7227: 7226: 7224: 7223: 7215: 7206: 7204: 7202:Mirandornithes 7198: 7197: 7195: 7194: 7186: 7178: 7173:Columbiformes 7169: 7167: 7165:Columbimorphae 7158: 7149: 7139: 7138: 7135: 7134: 7131: 7130: 7127: 7126: 7124: 7123: 7118: 7110: 7105: 7100:Meleagridinae 7096: 7094: 7088: 7087: 7085: 7084: 7077: 7070: 7063: 7056: 7049: 7042: 7035: 7028: 7020: 7018: 7016:Odontophoridae 7012: 7011: 7009: 7008: 7001: 6994: 6987: 6979: 6977: 6971: 6970: 6968: 6967: 6960: 6953: 6946: 6939: 6932: 6925: 6917: 6915: 6909: 6908: 6906: 6905: 6900: 6895: 6889: 6887: 6878: 6857: 6856: 6853: 6852: 6850: 6849: 6841: 6839: 6833: 6832: 6830: 6829: 6822: 6814: 6812: 6806: 6805: 6803: 6802: 6797: 6795:Stictonettinae 6792: 6790:Dendrocygninae 6787: 6786: 6785: 6778: 6766: 6765: 6764: 6759: 6754: 6743: 6741: 6724: 6711: 6668: 6640: 6639: 6636: 6635: 6633: 6632: 6624: 6616: 6608: 6600: 6591: 6589: 6575: 6574: 6571: 6560: 6559: 6557: 6556: 6555: 6554: 6549: 6543:Notable birds 6541: 6536: 6531: 6526: 6521: 6516: 6511: 6505: 6503: 6499: 6498: 6496: 6495: 6493:Egg collecting 6490: 6485: 6480: 6475: 6470: 6465: 6460: 6455: 6450: 6445: 6444: 6443: 6433: 6428: 6423: 6418: 6412: 6410: 6402: 6401: 6399: 6398: 6393: 6388: 6383: 6378: 6376:Hesperornithes 6373: 6368: 6363: 6358: 6353: 6351:Ambiortiformes 6348: 6343: 6338: 6336:Enantiornithes 6333: 6328: 6323: 6318: 6310: 6308: 6302: 6301: 6299: 6298: 6293: 6288: 6283: 6278: 6277: 6276: 6271: 6260: 6258: 6252: 6251: 6249: 6248: 6243: 6238: 6233: 6228: 6223: 6218: 6213: 6208: 6203: 6198: 6193: 6187: 6185: 6179: 6178: 6176: 6175: 6170: 6165: 6160: 6155: 6150: 6145: 6140: 6139: 6138: 6128: 6123: 6117: 6115: 6109: 6108: 6106: 6105: 6099: 6096: 6095: 6085: 6083: 6082: 6075: 6068: 6060: 6053: 6052: 6046: 6038:Avian Medicine 6033: 6027: 6010: 6004: 5991: 5985: 5972: 5966: 5953: 5947: 5934: 5928: 5915: 5909: 5896: 5890: 5877: 5871: 5858: 5835: 5829: 5816: 5794: 5792: 5789: 5787: 5786: 5733: 5712:(2): 308–316. 5692: 5661: 5650:on 4 June 2012 5630: 5623: 5602: 5587: 5580: 5554: 5519: 5490:Sterna fuscata 5480: 5473: 5455: 5446: 5439: 5413: 5406: 5386: 5358: 5347:. 23 June 2010 5332: 5321:(6): 423–430. 5305: 5282: 5231: 5212:(3): 455–467. 5196: 5159:(3): 675–678. 5136: 5079: 5034: 4993: 4928: 4888: 4817:10.1086/303237 4811:(3): 261–270. 4780: 4762: 4743: 4734: 4667: 4612: 4546: 4480: 4433: 4426: 4408: 4399: 4392: 4374: 4367: 4343: 4336: 4312: 4291:(3): 144–150. 4266: 4259: 4232: 4225: 4199: 4170:(2): 521–530. 4150: 4143: 4125: 4118: 4100: 4074: 4067: 4046: 4019:(1): 118–128. 3998: 3979:(4): 469–471. 3953: 3924: 3915: 3908: 3890: 3881: 3858: 3851: 3833: 3826: 3808: 3780: 3771: 3756: 3749: 3725: 3696:(2): 171–173. 3676: 3647:(2): 173–176. 3624: 3617: 3597: 3590: 3570: 3559: 3538: 3501: 3494: 3468: 3461: 3437: 3396: 3371: 3364: 3340: 3333: 3309: 3302: 3284: 3277: 3250: 3228: 3225:on 2012-10-21. 3189: 3170:(9): 759–777. 3150: 3095: 3068:(4): 839–848. 3052: 3003: 3000:on 2012-03-20. 2977:(4): 497–503. 2954: 2893: 2860:(3): 808–818. 2837: 2830: 2810: 2803: 2785: 2773: 2764: 2755: 2728:(4): 606–611. 2702: 2695: 2672: 2665: 2647: 2621: 2591: 2562: 2544: 2537: 2519: 2512: 2494: 2467: 2454:(4): 461–477. 2429: 2410:(3): 590–604. 2394: 2355: 2336:(3): 356–359. 2313: 2286:) in Alaska". 2284:Aethia pygmaea 2274: 2257: 2238:(3): 736–738. 2215: 2206: 2197: 2190: 2134: 2127: 2109: 2098:(3): 167–171. 2075: 2046: 2043:on 2012-04-02. 2020:(2): 331–343. 1997: 1990: 1950: 1927:Coues, Elliott 1906: 1881: 1874: 1851: 1829: 1827: 1824: 1821: 1820: 1795: 1794: 1792: 1789: 1788: 1787: 1781: 1775: 1767: 1764: 1728:bill tip organ 1712: 1711:Bill tip organ 1709: 1690:corticosterone 1686:adrenal glands 1645:Main article: 1642: 1639: 1571:When billing, 1564: 1561: 1549:common ostrich 1512: 1509: 1484: 1481: 1454:Main article: 1451: 1448: 1430: 1427: 1401: 1398: 1393: 1390: 1333: 1330: 1297: 1294: 1241: 1238: 1218:house sparrows 1168: 1165: 1146:colors in the 1133:hormonal state 1095: 1092: 1032:Main article: 1017: 1014: 991: 988: 920: 917: 909:great curassow 858: 855: 846: 843: 787: 784: 730:nasal cavities 706: 703: 686:, such as the 573: 570: 561: 558: 542:gonydeal angle 529: 526: 464: 461: 445:nectar thieves 377: 374: 337:of the bird's 314: 311: 243: 240: 206: 203: 188:Middle English 175: 172: 109:ornithischians 61:, but also in 27:Part of a bird 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 7701: 7690: 7687: 7686: 7684: 7669: 7668: 7659: 7657: 7656: 7651: 7647: 7645: 7644: 7635: 7633: 7632: 7623: 7622: 7619: 7581: 7575: 7573: 7567: 7565: 7559: 7557: 7551: 7549: 7543: 7541: 7535: 7533: 7529:Strigiformes 7527: 7525: 7519: 7517: 7511: 7510: 7508: 7506: 7502: 7496: 7490: 7488: 7482: 7480: 7474: 7472: 7466: 7465: 7463: 7461: 7457: 7451: 7445: 7443: 7437: 7435: 7429: 7427: 7421: 7419: 7413: 7411: 7405: 7404: 7402: 7400: 7396: 7390: 7384: 7382: 7380:(tropicbirds) 7376: 7375: 7373: 7371: 7367: 7361: 7355: 7353: 7347: 7346: 7344: 7342: 7338: 7332: 7326: 7325: 7323: 7321: 7317: 7311: 7305: 7303: 7302:Podargiformes 7300: 7298: 7295: 7293: 7287: 7286: 7284: 7282: 7278: 7272: 7266: 7264: 7258: 7256: 7252:Cuculiformes 7250: 7249: 7247: 7245: 7241: 7238: 7236: 7232: 7222: 7216: 7214: 7208: 7207: 7205: 7203: 7199: 7193: 7187: 7185: 7179: 7177: 7171: 7170: 7168: 7166: 7162: 7159: 7157: 7153: 7150: 7148: 7144: 7140: 7122: 7119: 7117: 7111: 7109: 7106: 7104: 7098: 7097: 7095: 7093: 7089: 7083: 7082: 7078: 7076: 7075: 7071: 7069: 7068: 7064: 7062: 7061: 7057: 7055: 7054: 7050: 7048: 7047: 7043: 7041: 7040: 7036: 7034: 7033: 7029: 7027: 7026: 7022: 7021: 7019: 7017: 7013: 7007: 7006: 7002: 7000: 6999: 6995: 6993: 6992: 6988: 6986: 6985: 6981: 6980: 6978: 6976: 6972: 6966: 6965: 6961: 6959: 6958: 6954: 6952: 6951: 6950:Macrocephalon 6947: 6945: 6944: 6940: 6938: 6937: 6933: 6931: 6930: 6926: 6924: 6923: 6919: 6918: 6916: 6914: 6910: 6904: 6901: 6899: 6896: 6894: 6891: 6890: 6888: 6886: 6882: 6879: 6875: 6868: 6862: 6858: 6848: 6847: 6843: 6842: 6840: 6838: 6837:Anseranatidae 6834: 6828: 6827: 6823: 6821: 6820: 6816: 6815: 6813: 6811: 6807: 6801: 6798: 6796: 6793: 6791: 6788: 6784: 6779: 6777: 6772: 6771: 6770: 6767: 6763: 6760: 6758: 6755: 6753: 6750: 6749: 6748: 6745: 6744: 6742: 6738: 6732: 6728: 6725: 6719: 6715: 6712: 6708: 6702: 6676: 6672: 6669: 6667: 6645: 6641: 6631: 6625: 6623: 6617: 6615: 6611:Tinamiformes 6609: 6607: 6601: 6599: 6593: 6592: 6590: 6588: 6587:Palaeognathae 6584: 6580: 6576: 6569: 6565: 6561: 6553: 6550: 6548: 6545: 6544: 6542: 6540: 6537: 6535: 6532: 6530: 6527: 6525: 6522: 6520: 6517: 6515: 6512: 6510: 6507: 6506: 6504: 6500: 6494: 6491: 6489: 6486: 6484: 6481: 6479: 6476: 6474: 6473:Pigeon racing 6471: 6469: 6466: 6464: 6461: 6459: 6456: 6454: 6451: 6449: 6446: 6442: 6439: 6438: 6437: 6434: 6432: 6429: 6427: 6424: 6422: 6419: 6417: 6414: 6413: 6411: 6409: 6403: 6397: 6394: 6392: 6389: 6387: 6384: 6382: 6379: 6377: 6374: 6372: 6369: 6367: 6364: 6362: 6359: 6357: 6354: 6352: 6349: 6347: 6344: 6342: 6339: 6337: 6334: 6332: 6329: 6327: 6324: 6322: 6319: 6317: 6316: 6315:Archaeopteryx 6312: 6311: 6309: 6307: 6303: 6297: 6294: 6292: 6289: 6287: 6284: 6282: 6279: 6275: 6272: 6270: 6267: 6266: 6265: 6262: 6261: 6259: 6257: 6253: 6247: 6244: 6242: 6239: 6237: 6234: 6232: 6229: 6227: 6224: 6222: 6219: 6217: 6214: 6212: 6209: 6207: 6204: 6202: 6199: 6197: 6194: 6192: 6189: 6188: 6186: 6184: 6180: 6174: 6171: 6169: 6166: 6164: 6161: 6159: 6156: 6154: 6151: 6149: 6146: 6144: 6141: 6137: 6134: 6133: 6132: 6129: 6127: 6124: 6122: 6119: 6118: 6116: 6114: 6110: 6104: 6101: 6100: 6097: 6092: 6088: 6081: 6076: 6074: 6069: 6067: 6062: 6061: 6058: 6049: 6043: 6039: 6034: 6030: 6024: 6019: 6018: 6011: 6007: 6001: 5997: 5992: 5988: 5982: 5978: 5973: 5969: 5963: 5959: 5954: 5950: 5944: 5940: 5935: 5931: 5925: 5921: 5916: 5912: 5906: 5902: 5897: 5893: 5887: 5883: 5878: 5874: 5868: 5864: 5859: 5855: 5851: 5847: 5843: 5842: 5836: 5832: 5826: 5822: 5817: 5813: 5809: 5804: 5803: 5796: 5795: 5790: 5782: 5778: 5773: 5768: 5764: 5760: 5756: 5752: 5748: 5746: 5737: 5734: 5729: 5725: 5720: 5715: 5711: 5707: 5703: 5696: 5693: 5680: 5676: 5672: 5665: 5662: 5649: 5645: 5644:Pet Education 5641: 5634: 5631: 5626: 5620: 5616: 5609: 5607: 5603: 5598: 5591: 5588: 5583: 5577: 5573: 5568: 5567: 5558: 5555: 5550: 5546: 5542: 5538: 5534: 5530: 5523: 5520: 5515: 5511: 5507: 5503: 5499: 5495: 5491: 5484: 5481: 5476: 5470: 5466: 5459: 5456: 5450: 5447: 5442: 5436: 5432: 5427: 5426: 5417: 5414: 5409: 5403: 5399: 5398: 5390: 5387: 5375: 5374: 5369: 5362: 5359: 5346: 5345:Science Daily 5342: 5336: 5333: 5328: 5324: 5320: 5316: 5309: 5306: 5301: 5297: 5293: 5286: 5283: 5278: 5274: 5270: 5266: 5262: 5258: 5254: 5250: 5246: 5242: 5235: 5232: 5227: 5223: 5219: 5215: 5211: 5207: 5200: 5197: 5192: 5188: 5184: 5180: 5175: 5170: 5166: 5162: 5158: 5154: 5147: 5140: 5137: 5132: 5128: 5123: 5118: 5114: 5110: 5106: 5102: 5098: 5094: 5090: 5083: 5080: 5075: 5071: 5065: 5057: 5053: 5049: 5045: 5038: 5035: 5030: 5026: 5020: 5012: 5008: 5004: 4997: 4994: 4989: 4985: 4979: 4971: 4967: 4963: 4959: 4955: 4951: 4947: 4943: 4939: 4932: 4929: 4918:on 2018-02-19 4914: 4910: 4906: 4905:British Birds 4899: 4892: 4889: 4884: 4880: 4874: 4860:on 2020-09-12 4856: 4852: 4848: 4844: 4840: 4836: 4832: 4827: 4822: 4818: 4814: 4810: 4806: 4799: 4791: 4789: 4787: 4785: 4781: 4776: 4772: 4766: 4763: 4758: 4754: 4747: 4744: 4738: 4735: 4730: 4726: 4721: 4716: 4712: 4708: 4703: 4698: 4694: 4690: 4686: 4682: 4678: 4671: 4668: 4663: 4659: 4655: 4651: 4647: 4643: 4639: 4635: 4631: 4627: 4623: 4616: 4613: 4608: 4604: 4600: 4596: 4592: 4588: 4584: 4580: 4576: 4572: 4568: 4564: 4560: 4553: 4551: 4547: 4542: 4538: 4534: 4530: 4526: 4522: 4518: 4514: 4510: 4506: 4502: 4498: 4494: 4487: 4485: 4481: 4476: 4472: 4468: 4464: 4460: 4456: 4452: 4448: 4444: 4437: 4434: 4429: 4423: 4419: 4412: 4409: 4403: 4400: 4395: 4389: 4385: 4378: 4375: 4370: 4364: 4360: 4356: 4355: 4347: 4344: 4339: 4333: 4329: 4325: 4324: 4316: 4313: 4308: 4304: 4299: 4294: 4290: 4286: 4282: 4275: 4273: 4271: 4267: 4262: 4256: 4251: 4250: 4241: 4239: 4237: 4233: 4228: 4222: 4218: 4210: 4208: 4206: 4204: 4200: 4195: 4191: 4187: 4183: 4178: 4173: 4169: 4165: 4161: 4154: 4151: 4146: 4140: 4136: 4129: 4126: 4121: 4115: 4111: 4104: 4101: 4097:(3): 268–278. 4096: 4092: 4085: 4078: 4075: 4070: 4064: 4060: 4053: 4051: 4047: 4042: 4038: 4034: 4030: 4026: 4022: 4018: 4014: 4007: 4005: 4003: 3999: 3994: 3990: 3986: 3982: 3978: 3974: 3967: 3960: 3958: 3954: 3950:(2): 193–197. 3949: 3945: 3938: 3931: 3929: 3925: 3919: 3916: 3911: 3905: 3901: 3894: 3891: 3885: 3882: 3877: 3873: 3869: 3862: 3859: 3854: 3848: 3844: 3837: 3834: 3829: 3823: 3819: 3812: 3809: 3804: 3800: 3796: 3795: 3787: 3785: 3781: 3775: 3772: 3767: 3760: 3757: 3752: 3746: 3742: 3738: 3737: 3729: 3726: 3721: 3717: 3712: 3707: 3703: 3699: 3695: 3691: 3687: 3680: 3677: 3672: 3668: 3663: 3658: 3654: 3650: 3646: 3642: 3638: 3631: 3629: 3625: 3620: 3614: 3610: 3609: 3601: 3598: 3593: 3587: 3583: 3582: 3574: 3571: 3568: 3563: 3560: 3555: 3548: 3542: 3539: 3531: 3527: 3523: 3516: 3514: 3505: 3502: 3497: 3491: 3487: 3482: 3481: 3472: 3469: 3464: 3458: 3454: 3450: 3449: 3441: 3438: 3433: 3429: 3424: 3419: 3415: 3411: 3407: 3400: 3397: 3392: 3388: 3384: 3383: 3375: 3372: 3367: 3361: 3357: 3353: 3352: 3344: 3341: 3336: 3330: 3326: 3322: 3321: 3313: 3310: 3305: 3299: 3295: 3288: 3285: 3280: 3274: 3270: 3266: 3265: 3257: 3255: 3251: 3239: 3232: 3229: 3224: 3220: 3216: 3213:(5): 461–64. 3212: 3208: 3204: 3202: 3201:Cuculus fugax 3193: 3190: 3185: 3181: 3177: 3173: 3169: 3165: 3161: 3154: 3151: 3135: 3130: 3125: 3121: 3117: 3110: 3108: 3099: 3096: 3091: 3087: 3083: 3079: 3075: 3071: 3067: 3063: 3056: 3053: 3048: 3044: 3039: 3034: 3030: 3026: 3022: 3018: 3014: 3007: 3004: 2996: 2992: 2988: 2984: 2980: 2976: 2972: 2965: 2958: 2955: 2950: 2946: 2941: 2936: 2931: 2926: 2922: 2918: 2915:(5): e10509. 2914: 2910: 2909: 2904: 2897: 2894: 2883:on 2016-04-08 2879: 2875: 2871: 2867: 2863: 2859: 2855: 2848: 2841: 2838: 2833: 2827: 2823: 2822: 2814: 2811: 2806: 2800: 2796: 2789: 2786: 2780: 2778: 2774: 2768: 2765: 2759: 2756: 2751: 2747: 2743: 2739: 2735: 2731: 2727: 2723: 2716: 2709: 2707: 2703: 2698: 2692: 2688: 2681: 2679: 2677: 2673: 2668: 2662: 2658: 2651: 2648: 2644:(3): 703–710. 2643: 2639: 2632: 2625: 2622: 2618:(2): 316–324. 2617: 2613: 2606: 2604: 2595: 2592: 2587: 2581: 2573: 2569: 2565: 2559: 2555: 2548: 2545: 2540: 2534: 2530: 2523: 2520: 2515: 2509: 2505: 2498: 2495: 2490: 2486: 2482: 2478: 2471: 2468: 2462: 2457: 2453: 2449: 2445: 2438: 2436: 2434: 2430: 2425: 2421: 2417: 2413: 2409: 2405: 2398: 2395: 2390: 2386: 2382: 2378: 2374: 2370: 2366: 2359: 2356: 2351: 2347: 2343: 2339: 2335: 2331: 2324: 2317: 2314: 2309: 2305: 2301: 2297: 2293: 2289: 2285: 2278: 2275: 2270: 2269: 2261: 2258: 2253: 2249: 2245: 2241: 2237: 2233: 2226: 2219: 2216: 2210: 2207: 2201: 2198: 2193: 2187: 2183: 2175: 2173: 2171: 2169: 2167: 2165: 2163: 2161: 2159: 2157: 2155: 2153: 2151: 2149: 2147: 2145: 2143: 2141: 2139: 2135: 2130: 2124: 2120: 2113: 2110: 2105: 2101: 2097: 2093: 2086: 2079: 2076: 2063: 2059: 2058: 2050: 2047: 2039: 2035: 2031: 2027: 2023: 2019: 2015: 2008: 2001: 1998: 1993: 1987: 1983: 1975: 1973: 1971: 1969: 1967: 1965: 1963: 1961: 1959: 1957: 1955: 1951: 1946: 1942: 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624:house sparrow 620: 616: 614: 610: 606: 602: 594: 589: 583: 579: 571: 569: 567: 559: 557: 555: 551: 550:gonydeal spot 547: 543: 539: 535: 527: 525: 523: 519: 515: 511: 510:red crossbill 507: 502: 500: 496: 491: 486: 482: 478: 469: 462: 460: 458: 454: 450: 446: 442: 438: 434: 430: 425: 423: 419: 415: 411: 407: 403: 399: 395: 387: 382: 375: 373: 371: 367: 363: 358: 356: 352: 348: 344: 340: 336: 332: 328: 324: 320: 312: 310: 308: 304: 300: 296: 291: 288: 284: 276: 271: 267: 265: 261: 253: 248: 241: 239: 237: 233: 229: 225: 216: 211: 204: 202: 200: 196: 192: 189: 185: 181: 180:birds of prey 173: 171: 169: 163: 161: 157: 153: 149: 145: 141: 137: 133: 130: 126: 122: 118: 114: 110: 106: 105: 100: 96: 92: 88: 84: 80: 76: 72: 68: 64: 60: 56: 52: 48: 39: 33: 19: 7665: 7653: 7641: 7629: 7539:(mousebirds) 7537:Coliiformes 7407:Gaviiformes 7399:Aequornithes 7307:Apodiformes 7268:Otidiformes 7244:Otidimorphae 7191:(sandgrouse) 7113:Phasianinae 7079: 7072: 7065: 7060:Odontophorus 7058: 7051: 7044: 7037: 7030: 7023: 7003: 6996: 6989: 6982: 6962: 6955: 6948: 6941: 6934: 6927: 6920: 6898:Oreophasinae 6844: 6824: 6817: 6722:(waterfowls) 6718:Anseriformes 6468:Cockfighting 6453:Conservation 6448:Bird feeding 6436:Birdwatching 6426:Ornithomancy 6366:Gansuiformes 6313: 6306:Fossil birds 6196:Intelligence 6120: 6037: 6016: 5995: 5976: 5957: 5938: 5919: 5900: 5881: 5862: 5840: 5820: 5801: 5791:Bibliography 5754: 5750: 5744: 5736: 5709: 5705: 5695: 5683:. Retrieved 5674: 5664: 5652:. Retrieved 5648:the original 5643: 5633: 5614: 5596: 5590: 5565: 5557: 5535:(3): 82–88. 5532: 5528: 5522: 5500:(2): 197–9. 5497: 5493: 5489: 5483: 5465:Sociobiology 5464: 5458: 5449: 5424: 5416: 5396: 5389: 5377:. Retrieved 5371: 5361: 5349:. Retrieved 5344: 5335: 5318: 5314: 5308: 5291: 5285: 5244: 5240: 5234: 5209: 5205: 5199: 5156: 5152: 5139: 5096: 5092: 5082: 5064:cite journal 5047: 5043: 5037: 5019:cite journal 5010: 5007:Bird-Banding 5006: 5002: 4996: 4978:cite journal 4948:(1): 56–84. 4945: 4941: 4937: 4931: 4920:. Retrieved 4913:the original 4908: 4904: 4891: 4873:cite journal 4862:. Retrieved 4855:the original 4808: 4804: 4774: 4765: 4757:Reed College 4746: 4737: 4684: 4680: 4670: 4629: 4625: 4615: 4566: 4562: 4500: 4496: 4450: 4446: 4436: 4417: 4411: 4402: 4383: 4377: 4353: 4346: 4322: 4315: 4298:10.1650/7512 4288: 4284: 4248: 4216: 4167: 4163: 4153: 4134: 4128: 4109: 4103: 4094: 4090: 4077: 4058: 4016: 4012: 3976: 3972: 3947: 3943: 3918: 3899: 3893: 3884: 3867: 3861: 3842: 3836: 3817: 3811: 3793: 3774: 3765: 3759: 3735: 3728: 3693: 3689: 3679: 3644: 3640: 3607: 3600: 3580: 3573: 3562: 3553: 3541: 3530:the original 3525: 3521: 3512: 3504: 3479: 3471: 3447: 3440: 3413: 3409: 3399: 3381: 3374: 3350: 3343: 3319: 3312: 3293: 3287: 3263: 3242:. Retrieved 3231: 3223:the original 3210: 3206: 3200: 3192: 3167: 3163: 3159: 3153: 3141:. Retrieved 3134:the original 3122:(1): 16–22. 3119: 3115: 3109:) nestlings" 3106: 3098: 3065: 3061: 3055: 3020: 3016: 3006: 2995:the original 2974: 2970: 2957: 2912: 2906: 2896: 2885:. Retrieved 2878:the original 2857: 2853: 2840: 2820: 2813: 2794: 2788: 2767: 2758: 2725: 2721: 2686: 2656: 2650: 2641: 2637: 2624: 2615: 2611: 2602: 2594: 2553: 2547: 2528: 2522: 2503: 2497: 2483:(2): 42–50. 2480: 2476: 2470: 2451: 2447: 2407: 2403: 2397: 2372: 2368: 2364: 2358: 2333: 2329: 2316: 2294:(1): 90–98. 2291: 2287: 2283: 2277: 2267: 2260: 2235: 2231: 2218: 2209: 2200: 2181: 2118: 2112: 2095: 2091: 2078: 2066:. Retrieved 2062:the original 2056: 2049: 2038:the original 2017: 2013: 2000: 1981: 1931: 1897:. Retrieved 1893: 1884: 1865: 1840: 1833: 1808: 1804: 1799: 1772:Bird anatomy 1760:rhamphotheca 1748: 1740:Scolopacidae 1727: 1725: 1702: 1694: 1674:vent pecking 1650: 1632: 1625: 1622:rhinonyssids 1596: 1593: 1589:pair bonding 1584: 1580: 1578: 1536:salt marshes 1529: 1514: 1486: 1473: 1466: 1459: 1432: 1423:bird feeders 1403: 1395: 1342:prey animals 1335: 1289: 1285: 1280: 1276: 1272: 1269: 1265: 1261: 1257: 1253: 1250: 1245: 1243: 1222:testosterone 1211: 1182: 1161:conspecifics 1141: 1121: 1116:Phaeomelanin 1102:— primarily 1097: 1068: 1037: 993: 983: 979: 971:. Juvenile " 969:lesser scaup 962: 949:diving ducks 940: 934: 906: 876: 869: 867: 848: 832: 817: 807: 803: 801: 767: 723: 696: 691: 679: 656:barn swallow 653: 629: 608: 604: 601:bird anatomy 598: 565: 563: 549: 545: 541: 533: 531: 503: 476: 474: 457:Ross's goose 429:insectivores 426: 397: 393: 391: 359: 330: 326: 323:rhamphotheca 322: 316: 313:Rhamphotheca 292: 285:. Here, the 280: 273:Position of 257: 220: 198: 195:Anglo French 190: 182:, in modern 177: 167: 164: 125:rhynchosaurs 102: 98: 87:killing prey 54: 50: 46: 44: 7667:WikiProject 7577:Piciformes 7460:Australaves 7439:Suliformes 7357:Gruiformes 7212:(flamingos) 7121:Tetraoninae 7092:Phasianidae 7081:Rhynchortyx 7046:Dactylortyx 6913:Megapodidae 6903:Penelopinae 6861:Galliformes 6603:Rheiformes 6597:(ostriches) 6547:individuals 6421:Ornithology 6408:interaction 6163:Preen gland 5882:Ornithology 4775:LiveScience 4626:Development 2375:: 175–179. 1982:Ornithology 1670:cannibalism 1517:toco toucan 1501:noisy miner 1476:coevolution 1374:Woodpeckers 1362:compressive 1270:Dickkopf-3. 1240:Development 1148:ultraviolet 1108:carotenoids 1026:Arctic tern 898:ultraviolet 649:ultraviolet 641:Estrildidae 609:gape flange 514:common loon 441:hummingbird 402:Granivorous 366:albatrosses 360:While most 331:gnathotheca 321:called the 184:ornithology 160:cephalopods 121:dicynodonts 7417:(penguins) 7270:(bustards) 7108:Perdicinae 7053:Dendrortyx 7025:Callipepla 6957:Megapodius 6922:Aepypodius 6800:Tadorninae 6782:true geese 6613:(tinamous) 6572:Neornithes 6483:Pheasantry 6458:Aviculture 6226:Incubation 6216:Lek mating 5174:1808/16618 5153:The Condor 5050:: 93–110. 5003:Mallophage 4922:2018-02-18 4864:2019-09-05 4771:"Platypus" 4285:The Condor 3973:The Condor 3244:2010-06-25 2887:2013-10-31 2572:1099968357 2232:The Condor 1826:References 1614:Canada jay 1521:blood flow 1497:frogmouths 1386:arthropods 1366:nutcracker 1281:Dickkopf-3 1167:Dimorphism 1128:saturation 973:grey geese 913:budgerigar 902:wavelength 872:(from the 742:Cormorants 666:–mediated 660:correlated 566:commissure 560:Commissure 453:snow goose 422:mergansers 396:(singular 351:periosteum 327:rhinotheca 299:proximally 228:trabeculae 156:billfishes 152:pufferfish 144:platypuses 136:monotremes 113:pterosaurs 81:for food, 7486:(parrots) 7330:(hoatzin) 7281:Strisores 7262:(turacos) 7254:(cuckoos) 7183:(mesites) 7102:(turkeys) 7074:Philortyx 6991:Agelastes 6984:Acryllium 6975:Numididae 6964:Talegalla 6874:gamebirds 6867:landfowls 6846:Anseranas 6810:Anhimidae 6769:Anserinae 6552:fictional 6274:dinosaurs 6269:Theropoda 6256:Evolution 6201:Migration 6183:Behaviour 5854:263166207 5292:Ecography 5226:1600-0706 5183:0010-5422 5113:0962-8452 5013:: 23, 24. 4835:1537-5323 4711:0027-8424 4646:1477-9129 4591:0028-0836 4525:0036-8075 4475:205124061 4447:Evolution 3876:646859135 3164:Behaviour 3082:0003-3472 2601:"Scopate 2580:cite book 1945:263166207 1791:Footnotes 1647:Debeaking 1618:bird food 1534:found in 1358:cardinals 1354:grosbeaks 1346:passerine 1313:barn owls 1296:Functions 1277:β-catenin 1266:β-catenin 1226:castrated 1214:androgens 1195:hornbills 1112:Eumelanin 1088:songbirds 1058:, as are 1040:calcified 1034:Egg tooth 1016:Egg tooth 1006:vibrissae 929:mute swan 839:Tapaculos 820:seedsnipe 804:operculum 796:rock dove 786:Operculum 779:tubercule 718:tubercule 699:fledgling 645:passerine 635:families 632:altricial 613:mandibles 520:juvenile 339:epidermis 242:Mandibles 217:'s skull. 174:Etymology 117:cetaceans 95:courtship 7683:Category 7631:Category 7505:Afroaves 7433:(storks) 7235:Passerea 7220:(grebes) 7156:Columbea 7067:Oreortyx 7039:Cyrtonyx 6929:Alectura 6893:Cracinae 6885:Cracidae 6762:Oxyurini 6752:Aythyini 6747:Anatinae 6731:Anatidae 6478:Falconry 6441:big year 6296:Seabirds 6206:Foraging 6153:Feathers 5812:64013457 5781:21525059 5728:85254980 5685:16 April 5679:Archived 5654:16 April 5549:21323655 5351:12 March 5277:42756257 5269:19628866 5191:32708877 5131:15888414 4970:14825028 4843:10506542 4729:21368127 4662:10925294 4654:12975342 4599:16885984 4541:17226774 4533:15353802 4467:25964090 4307:85776106 4041:20407444 4033:21069752 3803:98001121 3720:19864276 3671:17148356 3391:11031934 3090:53170955 3047:12952627 2991:44030487 2949:20463902 2908:PLoS ONE 2750:86597085 2657:Wildfowl 2424:18430834 2389:38791844 2308:85982302 2034:19699818 1929:(1890). 1766:See also 1703:Amongst 1682:neuromas 1555:and the 1540:latitude 1499:and the 1456:Preening 1450:Preening 1435:platypus 1406:garganey 1370:pelicans 1325:platypus 1104:melanins 1100:pigments 1072:Megapode 1052:reptiles 953:molluscs 937:Anatidae 931:'s beak. 808:opercula 806:(plural 726:nostrils 692:C. fugax 637:Viduidae 518:plumaged 499:calipers 485:E. Coues 368:and the 343:vascular 215:barn owl 140:echidnas 132:tadpoles 91:preening 75:grasping 7643:Commons 7147:Neoaves 7032:Colinus 6998:Guttera 6936:Eulipoa 6757:Mergini 6621:(kiwis) 6605:(rheas) 6416:Ringing 6241:Hybrids 6236:Nesting 6191:Singing 6168:Plumage 6143:Dactyly 6113:Anatomy 6103:Outline 6093:: Aves) 5772:3203496 5706:The Auk 5514:6052126 5249:Bibcode 5241:Science 5122:1599863 4962:3273522 4851:4369897 4720:3053969 4689:Bibcode 4607:2416057 4571:Bibcode 4505:Bibcode 4497:Science 4194:5362278 4186:3881820 4015:(PDF). 3993:1367580 3711:2865047 3662:1618910 3522:Seabird 3432:3883510 3184:4535638 3143:27 June 3038:1698012 2940:2865545 2917:Bibcode 2874:1940542 2854:Ecology 2742:4514529 2638:The Auk 2404:The Auk 2350:1366249 2252:1369622 2068:27 July 1756:keratin 1752:parrots 1662:broiler 1654:poultry 1606:waxwing 1598:Gannets 1585:nebbing 1581:billing 1563:Billing 1545:ratites 1491:, some 1378:pecking 1338:raptors 1286:TGFβllr 1273:TGFβllr 1262:TGFβllr 1203:casques 1080:petrels 984:rostrum 896:has an 845:Rosette 829:pigeons 818:Attagis 775:falcons 758:boobies 754:gannets 746:darters 714:Falcons 672:antigen 538:ventral 536:is the 479:is the 418:shrikes 410:falcons 408:. Most 319:keratin 283:ratites 205:Anatomy 104:rostrum 79:probing 71:pecking 63:turtles 55:rostrum 7655:Portal 7531:(owls) 7005:Numida 6943:Leipoa 6826:Chauna 6819:Anhima 6514:Genera 6488:Imping 6406:Human 6246:Colony 6173:Vision 6158:Flight 6044: 6025: 6002: 5983: 5964: 5945: 5926: 5907: 5888: 5869: 5852: 5827: 5810: 5779: 5769: 5726: 5621: 5578: 5547: 5512: 5471: 5437: 5404: 5379:6 June 5275: 5267: 5224: 5189: 5181: 5129: 5119: 5111: 4968: 4960: 4849: 4841: 4833: 4727: 4717: 4709: 4660: 4652: 4644: 4605: 4597: 4589: 4563:Nature 4539: 4531: 4523: 4473: 4465: 4424: 4390: 4365: 4334: 4305: 4257: 4223: 4192: 4184: 4141: 4116: 4065: 4039: 4031: 3991: 3906: 3874: 3849: 3824: 3801: 3747: 3718: 3708: 3669: 3659: 3615: 3588: 3492: 3459: 3430: 3389: 3362: 3331: 3300: 3275: 3182: 3088: 3080: 3045: 3035: 2989: 2947: 2937: 2872: 2828: 2801: 2748: 2740: 2693: 2663: 2570: 2560: 2535: 2510: 2422: 2387: 2348: 2330:Condor 2306: 2250: 2188: 2125: 2032: 1988: 1943: 1899:1 July 1890:"Beak" 1872: 1742:, and 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