Beak - Knowledge

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: 7674: 1021: 791: 1320: 7698: 270: 247: 468: 7710: 1716: 38: 7686: 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

4475:"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. 5575:

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 5353:

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.

2979: 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 6581: 3534: 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 4653: 2006: 380: 6093: 6074: 6051: 6032: 6013: 5994: 5975: 5956: 5937: 5918: 5876: 5670: 5627: 5520: 5486: 5453: 4457: 4423: 4398: 4367: 4290: 4256: 4174: 4149: 4098: 3939: 3882: 3857: 3780: 3648: 3621: 3517: 3484: 3387: 3356: 3325: 3300: 2854: 2837: 2810: 2702: 2672: 2569: 2544: 2519: 2197: 2134: 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. 5119:

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 4589:

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: 7714: 6571: 553: 6353: 3261: 4784: 4115: 3997: 3968: 2608: 2330: 2232: 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 6268: 6258: 1461: 1185: 1127: 416:, principally those that prey on insects or lizards, also have one or more of these sharp projections, as do the 5536:

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

5196: 6594: 6576: 3018: 2638: 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 6599: 4886: 2410:

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

6566: 6378: 6328: 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

7031: 5362: 5288: 5245: 4720: 4654:"Conditional inactivation of Tgfbr2 in cranial neural crest causes cleft palate and calvaria defects" 4602: 4536: 3578: 2994: 2932: 2869: 2099: 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.

6561: 6453: 6393: 6338: 6118: 2919:"Sibling competition and conspicuousness of nestling gapes in altricial birds: A comparative study" 2371:

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).

2893: 2723:"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 7344: 6408: 6368: 6333: 5771: 5695: 5388: 5312: 5218: 4989: 4878: 4689: 4634: 4568: 4502: 4334: 4213: 4068: 4020: 3451: 3203: 3109: 3010: 2885: 2753: 2745: 2587: 2427: 2392: 2353: 2311: 2255: 1696: 1556: 1000: 893: 521: 66: 5893: 5748:

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".

3404: 3292: 3286: 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 7470: 7417: 7367: 6510: 6500: 6443: 6243: 6238: 6089: 6070: 6047: 6028: 6009: 5990: 5971: 5952: 5933: 5914: 5897: 5872: 5855: 5824: 5666: 5623: 5592: 5557: 5516: 5482: 5449: 5304: 5261: 5210: 5158: 5140: 4997: 4870: 4862: 4756: 4738: 4707:

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 7336: 6478: 6150: 5814: 5806: 5761: 5611: 5584: 5549: 5470: 5370: 5335: 5296: 5253: 5200: 5192: 5148: 5132: 5083: 4981: 4852: 4844: 4746: 4728: 4665: 4610: 4544: 4486: 4324: 4203: 4052: 4012: 3737: 3729: 3688: 3680: 3553: 3501: 3441: 3238: 3195: 3147: 3093: 3056: 3048: 3002: 2950: 2940: 2877: 2737: 2492: 2463: 2419: 2384: 2345: 2303: 2247: 2107: 2021: 1665: 1531: 1439: 1409: 1202: 1136: 1083: 1009: 976: 923: 873: 769: 667: 505: 494: 480: 448: 385: 334: 306: 235: 2980:"Coevolution, communication, and host-chick mimicry in parasitic finches: who mimics whom?" 709: 7568: 7396: 6866: 6388: 6373: 6311: 6210: 6138: 5420: 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: 5612: 1515:

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

456: 5366: 5292: 5249: 4724: 4606: 4540: 4474: 3824: 2998: 2936: 2873: 2103: 736:. In most bird species, the nares are located in the basal third of the upper mandible. 209: 7678: 7608: 7560: 7494: 7433: 7388: 7375: 7249: 7212: 7063: 6837: 6674: 6428: 6423: 6418: 6398: 6383: 6278: 6273: 6253: 6248: 6230: 6178: 6111: 5819: 5790: 5750:"Bill morphology or Ibises suggests a remote-tactile sensory system for prey detection" 5153: 5120: 5087: 4751: 4708: 4591:"The calmodulin pathway and evolution of elongated beak morphology in Darwin's finches" 4311:

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

3742: 3717: 3693: 3668: 3061: 3036: 2955: 2918: 1839: 1689: 1567: 1548: 1233: 908: 729: 683: 618: 444: 187: 151: 5887: 5257: 4524: 2496: 2057:

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

1930: 7730: 7616: 7600: 7523: 7515: 7349: 7147: 6997: 6884: 6842: 6642: 6634: 6556: 6520: 6438: 6362: 6063: 5848: 5588: 5471: 5443: 5374: 5339: 4857: 4506: 4279: 3502: 3472:

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

3242: 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: 6025:

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

5775: 5316: 5222: 4693: 4572: 4338: 4072: 3598: 3157: 3113: 3014: 2757: 2431: 2396: 2315: 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

7702: 7446: 7291: 7107: 6945: 6893: 6765: 6726: 6495: 6483: 6473: 6463: 6160: 4882: 4788: 4638: 3344:

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: 3097: 3035:

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: 4802: 4709:"Two developmental modules establish 3D beak-shape variation in Darwin's finches" 3638: 2945: 2025: 1889: 748:

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

7507: 7354: 7160: 7139: 7128: 7093: 6960: 6950: 6908: 6799: 6666: 6468: 6293: 6288: 6220: 6205: 6173: 5718: 2331:"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: 2741: 2693:

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

7624: 7486: 7425: 7404: 7236: 7220: 7155: 7100: 7072: 7004: 6969: 6847: 6695: 6530: 6505: 6263: 6023:

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

5553: 5389:"Evolution of bird bills: Birds reduce their 'heating bills' in cold climates" 3006: 2579: 2388: 2307: 2111: 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: 5901: 5265: 5214: 5144: 4866: 4822: 4820: 4818: 4816: 4742: 4677: 4622: 4590: 4556: 3907: 3152: 3105: 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

17: 7584: 7539: 7328: 7121: 7038: 7022: 7011: 6921: 6857: 6816: 6515: 6316: 6303: 6283: 6183: 5300: 4733: 4548: 3446: 3429: 3199: 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: 6065:

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

5850:

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

5828: 5810: 5766: 5749: 5596: 5308: 5162: 5136: 5001: 4874: 4760: 4685: 4630: 4564: 4498: 4281:

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

4064: 3875:

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

3751: 3733: 3702: 3684: 3070: 3052: 2964: 2801:

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

2468: 2451: 2423: 2033: 1715: 78: 74: 5561: 4225: 4208: 4191: 2483:

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

7552: 7282: 7257: 7203: 7114: 7086: 6976: 6940: 6932: 6914: 6809: 6794: 6778: 6525: 6488: 6321: 5121:"Adaptive significance of avian beak morphology for ectoparasite control" 3900:

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

2923: 1681: 1539: 1524: 1455: 1434: 1405: 1353: 1324: 1312: 1213: 1194: 1087: 1071: 936: 838: 636: 612: 498: 342: 214: 155: 143: 90: 4614: 1171: 1042:

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

7462: 7315: 7194: 7079: 7045: 6983: 6804: 6658: 6650: 6343: 6215: 6200: 6190: 4993: 4386:

Identify Yourself: The 50 most common birding identification challenges

4217: 4056: 4024: 3616:(14th ed.). Pearson Benjamin Cummings Prentice Hall. p. 111. 3557: 3455: 3207: 2889: 2749: 2357: 2259: 1755: 1661: 1653: 1605: 1377: 1369: 1132: 1103: 1099: 1051: 952: 816: 725: 671: 537: 517: 318: 139: 131: 116: 70: 37: 6103: 5205: 4669: 4490: 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.

7592: 7531: 7307: 7299: 7228: 7168: 7052: 6990: 6873: 6540: 6535: 6413: 4089:

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

3129:"Gape coloration reliably reflects immunocompetence of barn swallow ( 2562:

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: 5647:. Vol. 12. New York, NY: Marshall Cavendish Corp. p. 1680. 5178:"Influence of bill shape on ectoparasite load in western scrub-jays" 4985: 4016: 3716:

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

2881: 2349: 2251: 1372:' beaks are well adapted for scooping up and swallowing fish whole. 4848: 4084: 4082: 3902:. Carbondale, IL: Southern Illinois University Press. p. 179. 3378:. Vol. 1: Ostrich to Ducks. Barcelona: Lynx Edicions. p. 2233:"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

7478: 7265: 6828: 2639:"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: 5176:

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

5125:

Proceedings of the Royal Society of London B: Biological Sciences

4329: 4312: 2805:. Vol. 2. Belmont, CA: Thomson Brooks / Cole. p. 1255. 447:, as they can more effectively hold and cut through long or waxy 7454: 6821: 6784: 6754: 6134: 5859: 3834: 3414: 1735: 1381: 1206: 1176: 1059: 833: 435:

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

405: 302: 259: 251: 58: 6618: 6107: 4525:"Bmp4 and Morphological Variation of Beaks in Darwin's Finches" 3934:(5 ed.). Washington, DC: National Geographic. p. 40. 2182: 2180: 2178: 2176: 2174: 2172: 2170: 2168: 2166: 341:, growing from plates at the base of each mandible. There is a 7576: 6433: 6195: 5416:"Add this to life list: 'Birding' has inspired flock of words" 4285:. Boston, MA: Harvard University Press. pp. 20, 83, 155. 3430:"Organisms as functional machines: A connectivity explanation" 3037:"Conspicuous, ultravioletrich mouth colours in begging chicks" 2917:

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

2164: 2162: 2160: 2158: 2156: 2154: 2152: 2150: 2148: 2146: 1552: 1492: 1396:

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

1123: 369: 354: 4383:

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

4169:. Vancouver, BC: University of Washington Press. p. 26. 1600:

raise their bills high and repeatedly clatter them, the male

4414:

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

4355:

Sexual Selection and the Descent of Man: The Darwinian pivot

3409:. Vol. 6. New York: The Century Company. p. 4123. 2855:"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

5618:(4 ed.). London, UK: Routledge Classics 2001. p. 5197:

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

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

5791:"Vision, touch and object manipulation in Senegal parrots 4830:"Reciprocal Natural Selection on Host-Parasite Phenotypes" 4452:. Vol. 2. New York, NY: Academic Press. p. 371. 3826:

The Wild Fowl of the United States and British Possessions

3718:"Visual cues and parental favouritism in a nocturnal bird" 3341:

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

2770:

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

2452:"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) 4828:

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

3954:

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

3223:"Yellow wing-patch of a nestling Horsfield's hawk cuckoo 3186:) is not a supernormal stimulus for three common hosts". 2779:

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

5469:

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

5445:

The Audubon Society Encyclopedia of North American Birds

3771:. 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 4251:. Washington, DC: National Geographic. pp. 62–66. 4091:

New Generation Guide to the Birds of Britain and Europe

3599:

Webster's Unabridged Dictionary of the English Language

3291:. New Brunswick, NJ: Rutgers University Press. p. 3221:

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

2510:

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

5932:(2 ed.). New York, NY: W.H. Freeman and Company. 4968:

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

4093:. 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

5656: 5654: 5515:. Boston, MA: Harvard University Press. p. 227. 4358:. New Brunswick, NJ: Transaction Publishers. p. 4272: 4270: 4268: 3996:

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

3667:

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

3403:

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

2721:

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

6004:

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

3508:. 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

7551: 7506: 7445: 7416: 7387: 7366: 7327: 7290: 7281: 7248: 7211: 7202: 7193: 7138: 7062: 7021: 6959: 6931: 6907: 6883: 6856: 6777: 6764: 6725: 6694: 6633: 6549: 6452: 6352: 6302: 6229: 6159: 6044:

Manual of Ornithology: Avian Structure and Function

5913:(4 ed.). New York, NY: McGraw Hill Companies. 5789:Demery, Zoe P.; Chappell, J.; Martin, G.R. (2011). 5577:

The Journal of the Australia Veterinary Association

4389:. New York, NY: Houghton Mifflin Harcourt. p. 4144:. Washington, DC: National Geographic. p. 23. 3898:Goodman, Donald Charles; Fisher, Harvey I. (1962). 3318:

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 6062: 5847: 4278: 2667:. London, UK: Christopher Helm. pp. 143–144. 967:has a wider black nail than does the very similar 3227:induces miscognition by hosts: Mimicking a gape?" 1467:This overhang of the beak is thought to be under 5033:Worth, (1940). "A note on the dissemination of 4313:"Ultraviolet spots in king and emperor penguins" 3877:. Minocqua, WI: Willow Creek Press. p. 31. 3669:"Ultraviolet reflectance by the cere of raptors" 2697:. Bolinas, CA: Slate Creek Press. pp. 6–7. 2695:Identification Guide to North America Passerines 2613:: An adaptation for handling hard-shelled prey?" 2279:. 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 5867:Campbell, Bruce; Lack, Elizabeth, eds. (1985). 4713:Proceedings of the National Academy of Sciences 4241: 4239: 4237: 4235: 4142:National Geographic Complete Birds of the World 3930:Dunn, Jon L.; Alderfer, Jonathan, eds. (2006). 2188: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. 5663:Improving Animal Welfare: A practical approach 4787:. Biology 342: Animal Behavior. Portland, OR: 4418:. New York, NY: Houghton Mifflin. p. 76. 3998:"Rictal Bristle Function in Willow Flycatcher" 3768:Wildlife of Mexico: The Game Birds and Mammals 2445: 2443: 2441: 516:is all dark, while that of the very similarly 238:mechanism and one five-bar linkage mechanism. 6119: 6061:Rogers, Lesley J.; Kaplan, Gisela T. (2000). 6042:Proctor, Noble S.; Lynch, Patrick J. (1998). 4277:Rogers, Lesley J.; Kaplan, Gisela T. (2000). 4116:"Occurrence and timing of egg teeth in birds" 4038: 4036: 4034: 3829:. New York, NY: F. P. Harper. p. xviii. 3552:. Centre for Ecology & Hydrology: 22–40. 2978: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: 5100:: CS1 maint: multiple names: authors list ( 5055:: CS1 maint: multiple names: authors list ( 5014:: CS1 maint: multiple names: authors list ( 4909:: CS1 maint: multiple names: authors list ( 4306: 4304: 4302: 3347:. New York, NY: Simon and Schuster. p. 3280: 3278: 2539:. London, UK: Christopher Helm. p. 15. 2514:. London, UK: Christopher Helm. p. 66. 1920: 1918: 1916: 1914: 1912: 1910: 6008:. Vol. 3. London, UK: Academic Press. 3320:. Boulder, CO: Johnson Books. p. 110. 2787: 2785: 861:"Cere" redirects here. For other uses, see 724:Most species of birds have external nares ( 576:"Gape" redirects here. For other uses, see 7287: 7208: 7199: 7190: 6928: 6774: 6761: 6722: 6718: 6691: 6630: 6626: 6615: 6611: 6126: 6112: 6104: 5989:. New York, NY: Houghton Mifflin Company. 5104:) CS1 maint: numeric names: authors list ( 5059:) CS1 maint: numeric names: authors list ( 5018:) CS1 maint: numeric names: authors list ( 4913:) CS1 maint: numeric names: authors list ( 3991: 3989: 3962: 3960: 3475:. New York, NY: Crown Publishers. p. 2592:: 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 5889:Handbook of Field and General Ornithology 5818: 5765: 5688:"Bird Beaks: Anatomy, care, and diseases" 5204: 5152: 4856: 4750: 4732: 4328: 4207: 3932:Field Guide to the Birds of North America 3818: 3816: 3741: 3692: 3662: 3660: 3445: 3151: 3060: 2954: 2944: 2716: 2714: 2560:V. L. Bels; Ian Q. Whishaw, eds. (2019). 2485:Seminars in Avian and Exotic Pet Medicine 2467: 2276:The structure and classification of birds 1935:. London, UK: Macmillan and Co. pp. 1932:Handbook of Field and General Ornithology 6069:. Boston, MA: Harvard University Press. 6046:. New Haven, CT: Yale University Press. 5892:. London, UK: Macmillan and Co. p. 5643:Burton, Maurice; Burton, Robert (1980). 3640:Parrots: A Guide to Parrots of the World 3285:Capainolo, Peter; Butler, Carol (2010). 2231:Bonser, R.H. & Witter, M.S. (1993). 2129:. 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 5970:. Washington, DC: National Geographic. 5871:. Carlton, England: T and A.D. Poyser. 5645:The International Wildlife Encyclopedia 4114:Clark, George A. Jr. (September 1961). 2688: 2686: 2684: 2192:. 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 5665:. Oxfordshire, UK: CABI. p. 110. 5093: 5048: 5007: 4902: 2585: 1838:Partington, Charles Frederick (1835). 459:is pinkish-red, without darker tomia. 69:and a few mammals. A beak is used for 5477:. Boca Raton, FL: CRC Press. p. 4584: 4582: 4518: 4516: 4352:Campbell, Bernard Grant, ed. (1972). 4167:The Inner Bird: Anatomy and evolution 3406:The Century Dictionary and Cyclopedia 2127: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: 7685: 5951:. Oxford, UK: Blackwell Publishing. 5854:. New York, NY: Dover Publications. 5846:Armstrong, Edward Allworthy (1965). 2535:Harris, Tony; Franklin, Kim (2000). 2092:Organisms, Diversity & Evolution 1360:) have large, stout beaks with high 349:, which is attached directly to the 7709: 5968:National Geographic Bird Coloration 4249:National Geographic Bird Coloration 3969:"The Role of Avian Rictal Bristles" 3852:. London, UK: Collins. p. 24. 2663:Madge, Steve; Burn, Hilary (1988). 2456:Integrative and Comparative Biology 325:, which can be subdivided into the 5799:Proceedings of the Royal Society B 5088:10.1111/j.1474-919X.1960.tb05095.x 3920:King & McLelland (1985) p. 421 3810:King & McLelland (1985) p. 376 3637:Jupiter, Tony; Parr, Mike (2010). 927:The nail is the black tip of this 431:(preferring hard-shelled prey) or 25: 6587:Late Quaternary prehistoric birds 5949:Veterinary Nursing of Exotic Pets 5448:. New York, NY: Alfred A. Knopf. 5414:Bierma, Nathan (12 August 2004). 5258:10.1034/j.1600-0706.2001.940308.x 3613: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 7708: 7696: 7684: 7673: 7672: 7563:(New World vultures and condors) 5589:10.1111/j.1751-0813.2010.00681.x 5340:10.1111/j.1600-0587.2011.07002.x 3848:Perrins, Christopher M. (1974). 3243:10.1111/j.2005.0908-8857.03439.x 2607:Gosner, Kenneth L. (June 1993). 1054:are; instead, it is part of the 170:lead to the respiratory system. 5729:from the original on 2005-04-06 4928:Pomeroy, D.E. (February 1962). 4192:"The Control of Color in Birds" 3798: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 6027:. London, UK: Harper Collins. 4190:Ralph, Charles L. (May 1969). 3823:Elliot, Daniel Giraud (1898). 3765:Leopold, Aldo Starker (1972). 3375:Handbook of Birds of the World 2450:Stettenheim, Peter R. (2000). 1668:-induced behaviors, including 329:of the upper mandible and the 1: 5542:Journal of Medical Entomology 5334:. online first (2): 146–152. 3643:. A&C Black. p. 17. 3098:10.1016/j.anbehav.2005.01.007 2497:10.1016/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 5985:Howell, Steve N. G. (2007). 5375:10.1016/0306-4565(94)90042-6 2946:10.1371/journal.pone.0010509 2803:Biology: The Dynamic Science 2730:Journal of Field Ornithology 2296: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 7627:(woodpeckers and relatives) 6084:Samour, Jaime, ed. (2000). 4930:"Birds with abnormal bills" 4785:"Platypus electroreception" 3288:How Fast Can a Falcon Dive? 2826:Newman, Kenneth B. (2000). 2377:Doklady Biological Sciences 1844:. Orr & Smith. p. 1738:, shorebirds of the family 1008:). Studies have shown that 810:), a membraneous, horny or 7753: 7489:(cormorants and relatives) 6582:Extinct species since 1500 6006:Form and Function in Birds 5966:Hill, Geoffrey E. (2010). 5909:Gilbertson, Lance (1999). 5686:Race Foster; Marty Smith. 5511:Wilson, Edward O. (1980). 5355:Journal of Thermal Biology 4943:(2): 49–72. Archived from 4783:Patel, Meera (Fall 2007). 4247:Hill, Geoffrey E. (2010). 3800:. Tetra Press. p. 12. 3500:Kaplan, Gisela T. (2007). 2853:Wheelwright, N.T. (1985). 2742:10.1648/0273-8570-71.4.606 2273:Beddard, Frank E. (1898). 1644: 1453: 1031: 880: 860: 849:Some species, such as the 768:Species in the bird order 575: 29: 7668: 7619:(kingfishers and rollers) 7473:(albatrosses and petrels) 7357:(swifts and hummingbirds) 7339:(nightjars and relatives) 7189: 7163:(pheasants and relatives) 6721: 6690: 6629: 6625: 6614: 6610: 6146: 4140:Harris, Tim, ed. (2009). 3610:Eleanor Lawrence (2008). 3007:10.1007/s00265-006-0291-0 2637:Ornelas, Juan Francisco. 2389:10.1134/S0012496609020264 2308:10.1648/0273-8570-74.1.90 2112:10.1016/j.ode.2004.10.013 1186:intraspecific competition 524:is pale towards the tip. 7518:(seriemas and relatives) 7497:(pelicans and relatives) 5661:Grandin, Temple (2010). 5610:Partridge, Eric (2001). 5442:Terres, John K. (1980). 4165:Kaiser, Gary W. (2007). 3796:Alderton, David (1996). 3535:"Aging Atlantic puffins 3533:Harris, Mike P. (2014). 3428:Bock, Walter J. (1989). 3316:Gellhorn, Joyce (2007). 3262:"Backyard Mystery Birds" 3231:Journal of Avian Biology 2829:Newman's birds by colour 2537:Shrikes and Bush-Shrikes 2373:Dromaius novaehollandiae 2125:Kaiser, Gary W. (2007). 1774: – Anatomy of birds 1483:Communicative percussion 935:All birds of the family 222:internally by a complex 7611:(hornbills and hoopoes) 7526:(falcons and relatives) 5947:Girling, Simon (2003). 5928:Gill, Frank B. (1995). 5886:Coues, Elliott (1890). 5554:10.1093/jmedent/4.2.197 5473:Biology of Marine Birds 5301:10.1126/science.1175553 4974:Journal of Parasitology 4837:The American Naturalist 4809:. 4 August 2014. 27572. 4734:10.1073/pnas.1011480108 4549:10.1126/science.1098095 3264:. Bird Watcher's Digest 3200:10.1163/156853999501559 1980:Gill, Frank B. (1995). 1811:, etc. with images see 1419:Red-bellied woodpeckers 578:gaping (disambiguation) 437:coefficient of friction 7595:(trogons and quetzals) 7407:(cranes and relatives) 6677:(emus and cassowaries) 6567:Glossary of bird terms 6379:Confuciusornithiformes 5811:10.1098/rspb.2011.0374 5767:10.1525/auk.2009.09117 5137:10.1098/rspb.2004.3036 4972:L. in North America". 3873:Petrie, Chuck (2006). 3734:10.1098/rsbl.2009.0769 3685:10.1098/rsbl.2005.0434 3588:(factsheet). May 2011. 3579:"Skomer Island Puffin" 3153:10.1093/beheco/14.1.16 3053:10.1098/rsbl.2003.0009 3047:(Suppl 1): S‑25–S‑28. 2987:Behav. Ecol. Sociobiol 2832:. Struik. p. 14. 2424:10.1525/auk.2010.09122 2375:, Struthioniformes)". 2221: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: 7436:(kagu and sunbittern) 7399:(gulls and relatives) 6404:Songlingornithiformes 6369:Omnivoropterygiformes 6088:. London, UK: Mosby. 5987:Gulls of the Americas 5869:A Dictionary of Birds 5793:Poicephalus senegalus 5723:The Modern Apprentice 5501:Armstrong (1965) p. 7 4858:10536/DRO/DU:30056229 4450:Vitamins and hormones 4045:Journal of Morphology 3586:www.welshwildlife.org 3539:in summer and winter" 3469:Tudge, Colin (2009). 3447:10.1093/icb/29.3.1119 2791:Howell (2007), p. 23. 2564:. Cham, Switzerland. 2212:Girling (2003), p. 4. 2190: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) 7737:Parts of a bird beak 7258:Phoenicopteriformes 5719:"Coping your Raptor" 5717:Ash, Lydia (2020) . 2512:Raptors of the World 2469:10.1093/icb/40.4.461 2329: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 7229:Mesitornithiformes 7223:(doves and pigeons) 6557:Families and orders 6419:Ichthyornithiformes 6394:Patagopterygiformes 5805:(1725): 3687–3693. 5614:Shakespeare's bawdy 5367:1994JTBio..19..423P 5293:2009Sci...325..468T 5250:2001Oikos..94..455C 4725:2011PNAS..108.4057M 4615:10.1038/nature04843 4607:2006Natur.442..563A 4541:2004Sci...305.1462A 4535:(5689): 1462–1465. 4438:Howell (2007) p. 21 4416:The Shorebird Guide 4209:10.1093/icb/9.2.521 4123:The Wilson Bulletin 3976:The Wilson Bulletin 3260:Zickefoose, Julie. 2999:2007BEcoS..61..497H 2937:2010PLoSO...510509S 2874:1985Ecol...66..808W 2620:The Wilson Bulletin 2104:2005ODivE...5..167M 894:Eurasian scops-owls 67:non-avian dinosaurs 7571:(eagles and hawks) 7471:Procellariiformes 7376:Opisthocomiformes 7345:Steatornithiformes 6572:List by population 6409:Hongshanornithidae 6334:Evolution of birds 5911:Zoology Lab Manual 4773:Samour (2000) p. 7 4196:American Zoologist 4057:10.1002/jmor.10908 3967:Lederer, Roger J. 3558:10.61350/sbj.27.21 3537:Fratercula arctica 3434:American Zoologist 3140: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: 7724: 7723: 7664: 7663: 7660: 7659: 7656: 7655: 7652: 7651: 7648: 7647: 7644: 7643: 7640: 7639: 7636: 7635: 7457:(loons or divers) 7426:Phaethontiformes 7418:Phaethontimorphae 7368:Opisthocomiformes 7337:Caprimulgiformes 7277: 7276: 7266:Podicipediformes 7185: 7184: 7181: 7180: 7177: 7176: 6903: 6902: 6686: 6685: 6643:Struthioniformes 6511:Waterfowl hunting 6444:Gastornithiformes 6439:Aepyornithiformes 6429:Lithornithiformes 6095:978-0-7234-2960-9 6076:978-0-674-00827-4 6053:978-0-300-07619-6 6034:978-0-00-711332-3 6015:978-0-12-407503-0 5996:978-0-618-72641-7 5977:978-1-4262-0571-2 5958:978-1-4051-0747-1 5939:978-0-7167-2415-5 5920:978-0-07-237716-3 5878:978-0-85661-039-4 5672:978-1-84593-541-2 5629:978-0-415-25553-0 5522:978-0-674-81624-4 5488:978-0-8493-9882-7 5455:978-0-394-46651-4 5287:(5949): 468–470. 5131:(1565): 811–817. 4719:(10): 4057–4062. 4670:10.1242/dev.00708 4664:(21): 5269–5280. 4601:(7102): 563–567. 4491:10.1111/evo.12684 4459:978-0-12-709802-9 4425:978-0-618-43294-3 4400:978-0-618-51469-4 4369:978-0-202-02005-1 4292:978-0-674-00827-4 4258:978-1-4262-0571-2 4176:978-0-7748-1344-0 4151:978-1-4262-0403-6 4100:978-0-292-75532-1 3941:978-0-7922-5314-3 3884:978-1-59543-050-2 3859:978-0-00-212173-6 3782:978-0-520-00724-6 3650:978-1-4081-3575-4 3623:978-0-321-50579-8 3567:on June 11, 2016. 3519:978-0-643-09239-6 3486:978-0-307-34204-1 3389:978-84-87334-10-8 3358:978-0-671-65989-9 3327:978-1-55566-397-1 3302:978-0-8135-4790-9 2839:978-1-86872-448-2 2812:978-0-495-01033-3 2704:978-0-9618940-0-9 2674:978-0-7470-2201-5 2571:978-3-030-13739-7 2546:978-0-7136-3861-5 2521:978-0-7136-8026-3 2199:978-0-85661-039-4 2136:978-0-7748-1343-3 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 7744: 7712: 7711: 7700: 7688: 7687: 7676: 7675: 7628: 7620: 7612: 7604: 7601:Leptosomiformes 7596: 7588: 7580: 7572: 7569:Accipitriformes 7564: 7543: 7542:(perching birds) 7535: 7527: 7519: 7498: 7490: 7482: 7474: 7466: 7463:Sphenisciformes 7458: 7437: 7429: 7408: 7400: 7397:Charadriiformes 7379: 7358: 7340: 7319: 7311: 7308:Musophagiformes 7303: 7288: 7269: 7261: 7240: 7232: 7224: 7209: 7200: 7191: 7164: 7151: 6929: 6925: 6918: 6831: 6824: 6788: 6775: 6771: 6762: 6758: 6723: 6719: 6692: 6678: 6670: 6662: 6654: 6646: 6631: 6627: 6616: 6612: 6479:Bird collections 6434:Dinornithiformes 6339:Darwin's finches 6329:Origin of flight 6269:Seabird breeding 6259:Sexual selection 6128: 6121: 6114: 6105: 6099: 6080: 6068: 6057: 6038: 6019: 6000: 5981: 5962: 5943: 5924: 5905: 5882: 5863: 5853: 5833: 5832: 5822: 5786: 5780: 5779: 5769: 5745: 5739: 5738: 5736: 5734: 5714: 5708: 5707: 5705: 5703: 5694:. Archived from 5683: 5677: 5676: 5658: 5649: 5648: 5640: 5634: 5633: 5617: 5607: 5601: 5600: 5572: 5566: 5565: 5533: 5527: 5526: 5508: 5502: 5499: 5493: 5492: 5476: 5466: 5460: 5459: 5439: 5433: 5432: 5430: 5428: 5411: 5405: 5404: 5402: 5400: 5385: 5379: 5378: 5350: 5344: 5343: 5327: 5321: 5320: 5276: 5270: 5269: 5233: 5227: 5226: 5208: 5182: 5173: 5167: 5166: 5156: 5116: 5110: 5109: 5099: 5091: 5071: 5065: 5064: 5054: 5046: 5030: 5024: 5023: 5013: 5005: 4970:Sturnus vulgaris 4965: 4959: 4958: 4956: 4955: 4949: 4934: 4925: 4919: 4918: 4908: 4900: 4898: 4897: 4891: 4885:. Archived from 4860: 4834: 4824: 4811: 4810: 4799: 4793: 4792: 4780: 4774: 4771: 4765: 4764: 4754: 4736: 4704: 4698: 4697: 4649: 4643: 4642: 4586: 4577: 4576: 4520: 4511: 4510: 4485:(7): 1665–1677. 4470: 4464: 4463: 4445: 4439: 4436: 4430: 4429: 4411: 4405: 4404: 4380: 4374: 4373: 4349: 4343: 4342: 4332: 4308: 4297: 4296: 4284: 4274: 4263: 4262: 4243: 4230: 4229: 4211: 4187: 4181: 4180: 4162: 4156: 4155: 4137: 4131: 4130: 4120: 4111: 4105: 4104: 4086: 4077: 4076: 4040: 4029: 4028: 4002: 3993: 3984: 3983: 3973: 3964: 3955: 3952: 3946: 3945: 3927: 3921: 3918: 3912: 3911: 3895: 3889: 3888: 3870: 3864: 3863: 3845: 3839: 3838: 3820: 3811: 3808: 3802: 3801: 3793: 3787: 3786: 3762: 3756: 3755: 3745: 3713: 3707: 3706: 3696: 3664: 3655: 3654: 3634: 3628: 3627: 3607: 3601: 3596: 3590: 3589: 3583: 3575: 3569: 3568: 3566: 3560:. Archived from 3543: 3530: 3524: 3523: 3507: 3497: 3491: 3490: 3466: 3460: 3459: 3449: 3440:(3): 1119–1132. 3425: 3419: 3418: 3400: 3394: 3393: 3369: 3363: 3362: 3338: 3332: 3331: 3313: 3307: 3306: 3282: 3273: 3272: 3270: 3269: 3257: 3251: 3250: 3245:. Archived from 3218: 3212: 3211: 3179: 3173: 3172: 3170: 3168: 3162: 3156:. Archived from 3155: 3137: 3124: 3118: 3117: 3086:Animal Behaviour 3081: 3075: 3074: 3064: 3032: 3026: 3025: 3023: 3017:. Archived from 2984: 2975: 2969: 2968: 2958: 2948: 2914: 2908: 2907: 2905: 2904: 2898: 2892:. Archived from 2859: 2850: 2844: 2843: 2823: 2817: 2816: 2798: 2792: 2789: 2780: 2777: 2771: 2768: 2762: 2761: 2727: 2718: 2709: 2708: 2690: 2679: 2678: 2660: 2654: 2653: 2643: 2634: 2628: 2627: 2617: 2604: 2598: 2597: 2591: 2583: 2557: 2551: 2550: 2532: 2526: 2525: 2507: 2501: 2500: 2480: 2474: 2473: 2471: 2447: 2436: 2435: 2407: 2401: 2400: 2368: 2362: 2361: 2335: 2326: 2320: 2319: 2287: 2281: 2280: 2270: 2264: 2263: 2237: 2228: 2222: 2219: 2213: 2210: 2204: 2203: 2184: 2141: 2140: 2122: 2116: 2115: 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: 7752: 7751: 7747: 7746: 7745: 7743: 7742: 7741: 7727: 7726: 7725: 7720: 7632: 7626: 7618: 7610: 7609:Bucerotiformes 7603:(cuckoo-roller) 7602: 7594: 7586: 7578: 7570: 7562: 7561:Cathartiformes 7547: 7541: 7533: 7532:Psittaciformes 7525: 7517: 7502: 7496: 7495:Pelecaniformes 7488: 7480: 7472: 7464: 7456: 7441: 7435: 7434:Eurypygiformes 7427: 7412: 7406: 7398: 7383: 7377: 7362: 7356: 7338: 7323: 7317: 7309: 7301: 7273: 7267: 7259: 7244: 7238: 7237:Pterocliformes 7230: 7222: 7173: 7162: 7149: 7134: 7058: 7017: 6955: 6920: 6919: 6912: 6911: 6899: 6879: 6852: 6829: 6822: 6782: 6781: 6769: 6768: 6752: 6751: 6748: 6746: 6744: 6742: 6740: 6738: 6736: 6734: 6732: 6730: 6728: 6713: 6711: 6709: 6707: 6705: 6703: 6701: 6699: 6697: 6682: 6676: 6675:Casuariiformes 6668: 6667:Apterygiformes 6660: 6652: 6644: 6621: 6606: 6577:Lists by region 6545: 6455: 6448: 6389:Chaoyangiformes 6374:Jeholornithidae 6348: 6312:Origin of birds 6298: 6279:Brood parasites 6225: 6155: 6142: 6132: 6102: 6096: 6083: 6077: 6060: 6054: 6041: 6035: 6022: 6016: 6003: 5997: 5984: 5978: 5965: 5959: 5946: 5940: 5927: 5921: 5908: 5885: 5879: 5866: 5845: 5841: 5836: 5788: 5787: 5783: 5747: 5746: 5742: 5732: 5730: 5716: 5715: 5711: 5701: 5699: 5685: 5684: 5680: 5673: 5660: 5659: 5652: 5642: 5641: 5637: 5630: 5609: 5608: 5604: 5574: 5573: 5569: 5535: 5534: 5530: 5523: 5510: 5509: 5505: 5500: 5496: 5489: 5468: 5467: 5463: 5456: 5441: 5440: 5436: 5426: 5424: 5421:Chicago Tribune 5413: 5412: 5408: 5398: 5396: 5387: 5386: 5382: 5352: 5351: 5347: 5329: 5328: 5324: 5278: 5277: 5273: 5235: 5234: 5230: 5180: 5175: 5174: 5170: 5118: 5117: 5113: 5092: 5073: 5072: 5068: 5047: 5032: 5031: 5027: 5006: 4986:10.2307/3273522 4967: 4966: 4962: 4953: 4951: 4947: 4932: 4927: 4926: 4922: 4901: 4895: 4893: 4889: 4832: 4827: 4826: 4825: 4814: 4801: 4800: 4796: 4782: 4781: 4777: 4772: 4768: 4706: 4705: 4701: 4651: 4650: 4646: 4588: 4587: 4580: 4522: 4521: 4514: 4472: 4471: 4467: 4460: 4447: 4446: 4442: 4437: 4433: 4426: 4413: 4412: 4408: 4401: 4382: 4381: 4377: 4370: 4351: 4350: 4346: 4310: 4309: 4300: 4293: 4276: 4275: 4266: 4259: 4246: 4245: 4244: 4233: 4189: 4188: 4184: 4177: 4164: 4163: 4159: 4152: 4139: 4138: 4134: 4118: 4113: 4112: 4108: 4101: 4088: 4087: 4080: 4042: 4041: 4032: 4017:10.2307/1367580 4000: 3995: 3994: 3987: 3971: 3966: 3965: 3958: 3953: 3949: 3942: 3929: 3928: 3924: 3919: 3915: 3897: 3896: 3892: 3885: 3872: 3871: 3867: 3860: 3847: 3846: 3842: 3822: 3821: 3814: 3809: 3805: 3795: 3794: 3790: 3783: 3764: 3763: 3759: 3722:Biology Letters 3715: 3714: 3710: 3673:Biology Letters 3666: 3665: 3658: 3651: 3636: 3635: 3631: 3624: 3609: 3608: 3604: 3597: 3593: 3581: 3577: 3576: 3572: 3564: 3541: 3532: 3531: 3527: 3520: 3504:Tawny Frogmouth 3499: 3498: 3494: 3487: 3468: 3467: 3463: 3427: 3426: 3422: 3402: 3401: 3397: 3390: 3371: 3370: 3366: 3359: 3340: 3339: 3335: 3328: 3315: 3314: 3310: 3303: 3284: 3283: 3276: 3267: 3265: 3259: 3258: 3254: 3220: 3219: 3215: 3184:Cuculus canorus 3181: 3180: 3176: 3166: 3164: 3163:on 11 July 2011 3160: 3135: 3131:Hirundo rustica 3126: 3125: 3121: 3083: 3082: 3078: 3041:Biology Letters 3034: 3033: 3029: 3021: 2982: 2977: 2976: 2972: 2916: 2915: 2911: 2902: 2900: 2896: 2882:10.2307/1940542 2857: 2852: 2851: 2847: 2840: 2825: 2824: 2820: 2813: 2800: 2799: 2795: 2790: 2783: 2778: 2774: 2769: 2765: 2725: 2720: 2719: 2712: 2705: 2692: 2691: 2682: 2675: 2662: 2661: 2657: 2641: 2636: 2635: 2631: 2615: 2606: 2605: 2601: 2584: 2572: 2559: 2558: 2554: 2547: 2534: 2533: 2529: 2522: 2509: 2508: 2504: 2482: 2481: 2477: 2449: 2448: 2439: 2409: 2408: 2404: 2370: 2369: 2365: 2350:10.2307/1366249 2333: 2328: 2327: 2323: 2289: 2288: 2284: 2272: 2271: 2267: 2252:10.2307/1369622 2235: 2230: 2229: 2225: 2220: 2216: 2211: 2207: 2200: 2187: 2186: 2185: 2144: 2137: 2124: 2123: 2119: 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: 7750: 7748: 7740: 7739: 7729: 7728: 7722: 7721: 7719: 7718: 7706: 7694: 7682: 7669: 7666: 7665: 7662: 7661: 7658: 7657: 7654: 7653: 7650: 7649: 7646: 7645: 7642: 7641: 7638: 7637: 7634: 7633: 7631: 7630: 7622: 7617:Coraciiformes 7614: 7606: 7598: 7593:Trogoniformes 7590: 7582: 7574: 7566: 7557: 7555: 7549: 7548: 7546: 7545: 7540:Passeriformes 7537: 7529: 7524:Falconiformes 7521: 7516:Cariamiformes 7512: 7510: 7504: 7503: 7501: 7500: 7492: 7484: 7479:Ciconiiformes 7476: 7468: 7460: 7451: 7449: 7443: 7442: 7440: 7439: 7431: 7422: 7420: 7414: 7413: 7411: 7410: 7402: 7393: 7391: 7389:Cursorimorphae 7385: 7384: 7382: 7381: 7372: 7370: 7364: 7363: 7361: 7360: 7352: 7347: 7342: 7333: 7331: 7325: 7324: 7322: 7321: 7313: 7305: 7296: 7294: 7285: 7279: 7278: 7275: 7274: 7272: 7271: 7263: 7254: 7252: 7250:Mirandornithes 7246: 7245: 7243: 7242: 7234: 7226: 7221:Columbiformes 7217: 7215: 7213:Columbimorphae 7206: 7197: 7187: 7186: 7183: 7182: 7179: 7178: 7175: 7174: 7172: 7171: 7166: 7158: 7153: 7148:Meleagridinae 7144: 7142: 7136: 7135: 7133: 7132: 7125: 7118: 7111: 7104: 7097: 7090: 7083: 7076: 7068: 7066: 7064:Odontophoridae 7060: 7059: 7057: 7056: 7049: 7042: 7035: 7027: 7025: 7019: 7018: 7016: 7015: 7008: 7001: 6994: 6987: 6980: 6973: 6965: 6963: 6957: 6956: 6954: 6953: 6948: 6943: 6937: 6935: 6926: 6905: 6904: 6901: 6900: 6898: 6897: 6889: 6887: 6881: 6880: 6878: 6877: 6870: 6862: 6860: 6854: 6853: 6851: 6850: 6845: 6843:Stictonettinae 6840: 6838:Dendrocygninae 6835: 6834: 6833: 6826: 6814: 6813: 6812: 6807: 6802: 6791: 6789: 6772: 6759: 6716: 6688: 6687: 6684: 6683: 6681: 6680: 6672: 6664: 6656: 6648: 6639: 6637: 6623: 6622: 6619: 6608: 6607: 6605: 6604: 6603: 6602: 6597: 6591:Notable birds 6589: 6584: 6579: 6574: 6569: 6564: 6559: 6553: 6551: 6547: 6546: 6544: 6543: 6541:Egg collecting 6538: 6533: 6528: 6523: 6518: 6513: 6508: 6503: 6498: 6493: 6492: 6491: 6481: 6476: 6471: 6466: 6460: 6458: 6450: 6449: 6447: 6446: 6441: 6436: 6431: 6426: 6424:Hesperornithes 6421: 6416: 6411: 6406: 6401: 6399:Ambiortiformes 6396: 6391: 6386: 6384:Enantiornithes 6381: 6376: 6371: 6366: 6358: 6356: 6350: 6349: 6347: 6346: 6341: 6336: 6331: 6326: 6325: 6324: 6319: 6308: 6306: 6300: 6299: 6297: 6296: 6291: 6286: 6281: 6276: 6271: 6266: 6261: 6256: 6251: 6246: 6241: 6235: 6233: 6227: 6226: 6224: 6223: 6218: 6213: 6208: 6203: 6198: 6193: 6188: 6187: 6186: 6176: 6171: 6165: 6163: 6157: 6156: 6154: 6153: 6147: 6144: 6143: 6133: 6131: 6130: 6123: 6116: 6108: 6101: 6100: 6094: 6086:Avian Medicine 6081: 6075: 6058: 6052: 6039: 6033: 6020: 6014: 6001: 5995: 5982: 5976: 5963: 5957: 5944: 5938: 5925: 5919: 5906: 5883: 5877: 5864: 5842: 5840: 5837: 5835: 5834: 5781: 5760:(2): 308–316. 5740: 5709: 5698:on 4 June 2012 5678: 5671: 5650: 5635: 5628: 5602: 5567: 5538:Sterna fuscata 5528: 5521: 5503: 5494: 5487: 5461: 5454: 5434: 5406: 5395:. 23 June 2010 5380: 5361:(6): 423–430. 5345: 5322: 5271: 5244:(3): 455–467. 5228: 5191:(3): 675–678. 5168: 5111: 5066: 5025: 4960: 4920: 4849:10.1086/303237 4843:(3): 261–270. 4812: 4794: 4775: 4766: 4699: 4644: 4578: 4512: 4465: 4458: 4440: 4431: 4424: 4406: 4399: 4375: 4368: 4344: 4323:(3): 144–150. 4298: 4291: 4264: 4257: 4231: 4202:(2): 521–530. 4182: 4175: 4157: 4150: 4132: 4106: 4099: 4078: 4051:(1): 118–128. 4030: 4011:(4): 469–471. 3985: 3956: 3947: 3940: 3922: 3913: 3890: 3883: 3865: 3858: 3840: 3812: 3803: 3788: 3781: 3757: 3728:(2): 171–173. 3708: 3679:(2): 173–176. 3656: 3649: 3629: 3622: 3602: 3591: 3570: 3525: 3518: 3492: 3485: 3461: 3420: 3395: 3388: 3364: 3357: 3333: 3326: 3308: 3301: 3274: 3252: 3249:on 2012-10-21. 3213: 3194:(9): 759–777. 3174: 3119: 3092:(4): 839–848. 3076: 3027: 3024:on 2012-03-20. 2993:(4): 497–503. 2970: 2909: 2868:(3): 808–818. 2845: 2838: 2818: 2811: 2793: 2781: 2772: 2763: 2736:(4): 606–611. 2710: 2703: 2680: 2673: 2655: 2629: 2599: 2570: 2552: 2545: 2527: 2520: 2502: 2475: 2462:(4): 461–477. 2437: 2418:(3): 590–604. 2402: 2363: 2344:(3): 356–359. 2321: 2294:) in Alaska". 2292:Aethia pygmaea 2282: 2265: 2246:(3): 736–738. 2223: 2214: 2205: 2198: 2142: 2135: 2117: 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: 7749: 7738: 7735: 7734: 7732: 7717: 7716: 7707: 7705: 7704: 7699: 7695: 7693: 7692: 7683: 7681: 7680: 7671: 7670: 7667: 7629: 7623: 7621: 7615: 7613: 7607: 7605: 7599: 7597: 7591: 7589: 7583: 7581: 7577:Strigiformes 7575: 7573: 7567: 7565: 7559: 7558: 7556: 7554: 7550: 7544: 7538: 7536: 7530: 7528: 7522: 7520: 7514: 7513: 7511: 7509: 7505: 7499: 7493: 7491: 7485: 7483: 7477: 7475: 7469: 7467: 7461: 7459: 7453: 7452: 7450: 7448: 7444: 7438: 7432: 7430: 7428:(tropicbirds) 7424: 7423: 7421: 7419: 7415: 7409: 7403: 7401: 7395: 7394: 7392: 7390: 7386: 7380: 7374: 7373: 7371: 7369: 7365: 7359: 7353: 7351: 7350:Podargiformes 7348: 7346: 7343: 7341: 7335: 7334: 7332: 7330: 7326: 7320: 7314: 7312: 7306: 7304: 7300:Cuculiformes 7298: 7297: 7295: 7293: 7289: 7286: 7284: 7280: 7270: 7264: 7262: 7256: 7255: 7253: 7251: 7247: 7241: 7235: 7233: 7227: 7225: 7219: 7218: 7216: 7214: 7210: 7207: 7205: 7201: 7198: 7196: 7192: 7188: 7170: 7167: 7165: 7159: 7157: 7154: 7152: 7146: 7145: 7143: 7141: 7137: 7131: 7130: 7126: 7124: 7123: 7119: 7117: 7116: 7112: 7110: 7109: 7105: 7103: 7102: 7098: 7096: 7095: 7091: 7089: 7088: 7084: 7082: 7081: 7077: 7075: 7074: 7070: 7069: 7067: 7065: 7061: 7055: 7054: 7050: 7048: 7047: 7043: 7041: 7040: 7036: 7034: 7033: 7029: 7028: 7026: 7024: 7020: 7014: 7013: 7009: 7007: 7006: 7002: 7000: 6999: 6998:Macrocephalon 6995: 6993: 6992: 6988: 6986: 6985: 6981: 6979: 6978: 6974: 6972: 6971: 6967: 6966: 6964: 6962: 6958: 6952: 6949: 6947: 6944: 6942: 6939: 6938: 6936: 6934: 6930: 6927: 6923: 6916: 6910: 6906: 6896: 6895: 6891: 6890: 6888: 6886: 6885:Anseranatidae 6882: 6876: 6875: 6871: 6869: 6868: 6864: 6863: 6861: 6859: 6855: 6849: 6846: 6844: 6841: 6839: 6836: 6832: 6827: 6825: 6820: 6819: 6818: 6815: 6811: 6808: 6806: 6803: 6801: 6798: 6797: 6796: 6793: 6792: 6790: 6786: 6780: 6776: 6773: 6767: 6763: 6760: 6756: 6750: 6724: 6720: 6717: 6715: 6693: 6689: 6679: 6673: 6671: 6665: 6663: 6659:Tinamiformes 6657: 6655: 6649: 6647: 6641: 6640: 6638: 6636: 6635:Palaeognathae 6632: 6628: 6624: 6617: 6613: 6609: 6601: 6598: 6596: 6593: 6592: 6590: 6588: 6585: 6583: 6580: 6578: 6575: 6573: 6570: 6568: 6565: 6563: 6560: 6558: 6555: 6554: 6552: 6548: 6542: 6539: 6537: 6534: 6532: 6529: 6527: 6524: 6522: 6521:Pigeon racing 6519: 6517: 6514: 6512: 6509: 6507: 6504: 6502: 6499: 6497: 6494: 6490: 6487: 6486: 6485: 6482: 6480: 6477: 6475: 6472: 6470: 6467: 6465: 6462: 6461: 6459: 6457: 6451: 6445: 6442: 6440: 6437: 6435: 6432: 6430: 6427: 6425: 6422: 6420: 6417: 6415: 6412: 6410: 6407: 6405: 6402: 6400: 6397: 6395: 6392: 6390: 6387: 6385: 6382: 6380: 6377: 6375: 6372: 6370: 6367: 6365: 6364: 6363:Archaeopteryx 6360: 6359: 6357: 6355: 6351: 6345: 6342: 6340: 6337: 6335: 6332: 6330: 6327: 6323: 6320: 6318: 6315: 6314: 6313: 6310: 6309: 6307: 6305: 6301: 6295: 6292: 6290: 6287: 6285: 6282: 6280: 6277: 6275: 6272: 6270: 6267: 6265: 6262: 6260: 6257: 6255: 6252: 6250: 6247: 6245: 6242: 6240: 6237: 6236: 6234: 6232: 6228: 6222: 6219: 6217: 6214: 6212: 6209: 6207: 6204: 6202: 6199: 6197: 6194: 6192: 6189: 6185: 6182: 6181: 6180: 6177: 6175: 6172: 6170: 6167: 6166: 6164: 6162: 6158: 6152: 6149: 6148: 6145: 6140: 6136: 6129: 6124: 6122: 6117: 6115: 6110: 6109: 6106: 6097: 6091: 6087: 6082: 6078: 6072: 6067: 6066: 6059: 6055: 6049: 6045: 6040: 6036: 6030: 6026: 6021: 6017: 6011: 6007: 6002: 5998: 5992: 5988: 5983: 5979: 5973: 5969: 5964: 5960: 5954: 5950: 5945: 5941: 5935: 5931: 5926: 5922: 5916: 5912: 5907: 5903: 5899: 5895: 5891: 5890: 5884: 5880: 5874: 5870: 5865: 5861: 5857: 5852: 5851: 5844: 5843: 5838: 5830: 5826: 5821: 5816: 5812: 5808: 5804: 5800: 5796: 5794: 5785: 5782: 5777: 5773: 5768: 5763: 5759: 5755: 5751: 5744: 5741: 5728: 5724: 5720: 5713: 5710: 5697: 5693: 5692:Pet Education 5689: 5682: 5679: 5674: 5668: 5664: 5657: 5655: 5651: 5646: 5639: 5636: 5631: 5625: 5621: 5616: 5615: 5606: 5603: 5598: 5594: 5590: 5586: 5582: 5578: 5571: 5568: 5563: 5559: 5555: 5551: 5547: 5543: 5539: 5532: 5529: 5524: 5518: 5514: 5507: 5504: 5498: 5495: 5490: 5484: 5480: 5475: 5474: 5465: 5462: 5457: 5451: 5447: 5446: 5438: 5435: 5423: 5422: 5417: 5410: 5407: 5394: 5393:Science Daily 5390: 5384: 5381: 5376: 5372: 5368: 5364: 5360: 5356: 5349: 5346: 5341: 5337: 5333: 5326: 5323: 5318: 5314: 5310: 5306: 5302: 5298: 5294: 5290: 5286: 5282: 5275: 5272: 5267: 5263: 5259: 5255: 5251: 5247: 5243: 5239: 5232: 5229: 5224: 5220: 5216: 5212: 5207: 5202: 5198: 5194: 5190: 5186: 5179: 5172: 5169: 5164: 5160: 5155: 5150: 5146: 5142: 5138: 5134: 5130: 5126: 5122: 5115: 5112: 5107: 5103: 5097: 5089: 5085: 5081: 5077: 5070: 5067: 5062: 5058: 5052: 5044: 5040: 5036: 5029: 5026: 5021: 5017: 5011: 5003: 4999: 4995: 4991: 4987: 4983: 4979: 4975: 4971: 4964: 4961: 4950:on 2018-02-19 4946: 4942: 4938: 4937:British Birds 4931: 4924: 4921: 4916: 4912: 4906: 4892:on 2020-09-12 4888: 4884: 4880: 4876: 4872: 4868: 4864: 4859: 4854: 4850: 4846: 4842: 4838: 4831: 4823: 4821: 4819: 4817: 4813: 4808: 4804: 4798: 4795: 4790: 4786: 4779: 4776: 4770: 4767: 4762: 4758: 4753: 4748: 4744: 4740: 4735: 4730: 4726: 4722: 4718: 4714: 4710: 4703: 4700: 4695: 4691: 4687: 4683: 4679: 4675: 4671: 4667: 4663: 4659: 4655: 4648: 4645: 4640: 4636: 4632: 4628: 4624: 4620: 4616: 4612: 4608: 4604: 4600: 4596: 4592: 4585: 4583: 4579: 4574: 4570: 4566: 4562: 4558: 4554: 4550: 4546: 4542: 4538: 4534: 4530: 4526: 4519: 4517: 4513: 4508: 4504: 4500: 4496: 4492: 4488: 4484: 4480: 4476: 4469: 4466: 4461: 4455: 4451: 4444: 4441: 4435: 4432: 4427: 4421: 4417: 4410: 4407: 4402: 4396: 4392: 4388: 4387: 4379: 4376: 4371: 4365: 4361: 4357: 4356: 4348: 4345: 4340: 4336: 4331: 4326: 4322: 4318: 4314: 4307: 4305: 4303: 4299: 4294: 4288: 4283: 4282: 4273: 4271: 4269: 4265: 4260: 4254: 4250: 4242: 4240: 4238: 4236: 4232: 4227: 4223: 4219: 4215: 4210: 4205: 4201: 4197: 4193: 4186: 4183: 4178: 4172: 4168: 4161: 4158: 4153: 4147: 4143: 4136: 4133: 4129:(3): 268–278. 4128: 4124: 4117: 4110: 4107: 4102: 4096: 4092: 4085: 4083: 4079: 4074: 4070: 4066: 4062: 4058: 4054: 4050: 4046: 4039: 4037: 4035: 4031: 4026: 4022: 4018: 4014: 4010: 4006: 3999: 3992: 3990: 3986: 3982:(2): 193–197. 3981: 3977: 3970: 3963: 3961: 3957: 3951: 3948: 3943: 3937: 3933: 3926: 3923: 3917: 3914: 3909: 3905: 3901: 3894: 3891: 3886: 3880: 3876: 3869: 3866: 3861: 3855: 3851: 3844: 3841: 3836: 3832: 3828: 3827: 3819: 3817: 3813: 3807: 3804: 3799: 3792: 3789: 3784: 3778: 3774: 3770: 3769: 3761: 3758: 3753: 3749: 3744: 3739: 3735: 3731: 3727: 3723: 3719: 3712: 3709: 3704: 3700: 3695: 3690: 3686: 3682: 3678: 3674: 3670: 3663: 3661: 3657: 3652: 3646: 3642: 3641: 3633: 3630: 3625: 3619: 3615: 3614: 3606: 3603: 3600: 3595: 3592: 3587: 3580: 3574: 3571: 3563: 3559: 3555: 3551: 3547: 3540: 3538: 3529: 3526: 3521: 3515: 3511: 3506: 3505: 3496: 3493: 3488: 3482: 3478: 3474: 3473: 3465: 3462: 3457: 3453: 3448: 3443: 3439: 3435: 3431: 3424: 3421: 3416: 3412: 3408: 3407: 3399: 3396: 3391: 3385: 3381: 3377: 3376: 3368: 3365: 3360: 3354: 3350: 3346: 3345: 3337: 3334: 3329: 3323: 3319: 3312: 3309: 3304: 3298: 3294: 3290: 3289: 3281: 3279: 3275: 3263: 3256: 3253: 3248: 3244: 3240: 3237:(5): 461–64. 3236: 3232: 3228: 3226: 3225:Cuculus fugax 3217: 3214: 3209: 3205: 3201: 3197: 3193: 3189: 3185: 3178: 3175: 3159: 3154: 3149: 3145: 3141: 3134: 3132: 3123: 3120: 3115: 3111: 3107: 3103: 3099: 3095: 3091: 3087: 3080: 3077: 3072: 3068: 3063: 3058: 3054: 3050: 3046: 3042: 3038: 3031: 3028: 3020: 3016: 3012: 3008: 3004: 3000: 2996: 2992: 2988: 2981: 2974: 2971: 2966: 2962: 2957: 2952: 2947: 2942: 2938: 2934: 2931:(5): e10509. 2930: 2926: 2925: 2920: 2913: 2910: 2899:on 2016-04-08 2895: 2891: 2887: 2883: 2879: 2875: 2871: 2867: 2863: 2856: 2849: 2846: 2841: 2835: 2831: 2830: 2822: 2819: 2814: 2808: 2804: 2797: 2794: 2788: 2786: 2782: 2776: 2773: 2767: 2764: 2759: 2755: 2751: 2747: 2743: 2739: 2735: 2731: 2724: 2717: 2715: 2711: 2706: 2700: 2696: 2689: 2687: 2685: 2681: 2676: 2670: 2666: 2659: 2656: 2652:(3): 703–710. 2651: 2647: 2640: 2633: 2630: 2626:(2): 316–324. 2625: 2621: 2614: 2612: 2603: 2600: 2595: 2589: 2581: 2577: 2573: 2567: 2563: 2556: 2553: 2548: 2542: 2538: 2531: 2528: 2523: 2517: 2513: 2506: 2503: 2498: 2494: 2490: 2486: 2479: 2476: 2470: 2465: 2461: 2457: 2453: 2446: 2444: 2442: 2438: 2433: 2429: 2425: 2421: 2417: 2413: 2406: 2403: 2398: 2394: 2390: 2386: 2382: 2378: 2374: 2367: 2364: 2359: 2355: 2351: 2347: 2343: 2339: 2332: 2325: 2322: 2317: 2313: 2309: 2305: 2301: 2297: 2293: 2286: 2283: 2278: 2277: 2269: 2266: 2261: 2257: 2253: 2249: 2245: 2241: 2234: 2227: 2224: 2218: 2215: 2209: 2206: 2201: 2195: 2191: 2183: 2181: 2179: 2177: 2175: 2173: 2171: 2169: 2167: 2165: 2163: 2161: 2159: 2157: 2155: 2153: 2151: 2149: 2147: 2143: 2138: 2132: 2128: 2121: 2118: 2113: 2109: 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: 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1387: 1383: 1379: 1375: 1371: 1367: 1363: 1359: 1355: 1351: 1347: 1343: 1339: 1331: 1326: 1321: 1314: 1295: 1293: 1291: 1287: 1282: 1278: 1274: 1271: 1267: 1263: 1259: 1255: 1249: 1247: 1239: 1237: 1235: 1231: 1227: 1223: 1219: 1215: 1210: 1208: 1204: 1200: 1196: 1191: 1187: 1178: 1173: 1166: 1164: 1162: 1158: 1154: 1149: 1145: 1140: 1138: 1134: 1129: 1125: 1120: 1117: 1113: 1109: 1105: 1101: 1093: 1091: 1089: 1085: 1081: 1077: 1073: 1067: 1065: 1061: 1057: 1053: 1049: 1045: 1041: 1035: 1027: 1022: 1015: 1013: 1011: 1007: 1002: 997: 996:insectivorous 989: 987: 985: 981: 978: 974: 970: 966: 965:greater scaup 961: 959: 954: 950: 946: 942: 938: 930: 925: 918: 916: 914: 910: 905: 903: 899: 895: 891: 886: 882: 878: 875: 871: 864: 856: 854: 852: 844: 842: 840: 836: 835: 830: 825: 821: 819: 813: 812:cartilaginous 809: 805: 797: 792: 785: 783: 780: 776: 771: 766: 763: 759: 755: 751: 747: 743: 739: 735: 731: 727: 719: 716:have a small 715: 711: 704: 702: 700: 695: 693: 689: 685: 681: 677: 676:common cuckoo 673: 669: 665: 661: 657: 652: 650: 646: 642: 638: 633: 625: 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: 18:Culmen (beak) 7713: 7701: 7689: 7677: 7587:(mousebirds) 7585:Coliiformes 7455:Gaviiformes 7447:Aequornithes 7355:Apodiformes 7316:Otidiformes 7292:Otidimorphae 7239:(sandgrouse) 7161:Phasianinae 7127: 7120: 7113: 7108:Odontophorus 7106: 7099: 7092: 7085: 7078: 7071: 7051: 7044: 7037: 7030: 7010: 7003: 6996: 6989: 6982: 6975: 6968: 6946:Oreophasinae 6892: 6872: 6865: 6770:(waterfowls) 6766:Anseriformes 6516:Cockfighting 6501:Conservation 6496:Bird feeding 6484:Birdwatching 6474:Ornithomancy 6414:Gansuiformes 6361: 6354:Fossil birds 6244:Intelligence 6168: 6085: 6064: 6043: 6024: 6005: 5986: 5967: 5948: 5929: 5910: 5888: 5868: 5849: 5839:Bibliography 5802: 5798: 5792: 5784: 5757: 5753: 5743: 5731:. Retrieved 5722: 5712: 5700:. Retrieved 5696:the original 5691: 5681: 5662: 5644: 5638: 5613: 5605: 5583:(3): 82–88. 5580: 5576: 5570: 5548:(2): 197–9. 5545: 5541: 5537: 5531: 5513:Sociobiology 5512: 5506: 5497: 5472: 5464: 5444: 5437: 5425:. Retrieved 5419: 5409: 5397:. Retrieved 5392: 5383: 5358: 5354: 5348: 5331: 5325: 5284: 5280: 5274: 5241: 5237: 5231: 5188: 5184: 5171: 5128: 5124: 5114: 5096:cite journal 5079: 5075: 5069: 5051:cite journal 5042: 5039:Bird-Banding 5038: 5034: 5028: 5010:cite journal 4980:(1): 56–84. 4977: 4973: 4969: 4963: 4952:. Retrieved 4945:the original 4940: 4936: 4923: 4905:cite journal 4894:. Retrieved 4887:the original 4840: 4836: 4806: 4797: 4789:Reed College 4778: 4769: 4716: 4712: 4702: 4661: 4657: 4647: 4598: 4594: 4532: 4528: 4482: 4478: 4468: 4449: 4443: 4434: 4415: 4409: 4385: 4378: 4354: 4347: 4330:10.1650/7512 4320: 4316: 4280: 4248: 4199: 4195: 4185: 4166: 4160: 4141: 4135: 4126: 4122: 4109: 4090: 4048: 4044: 4008: 4004: 3979: 3975: 3950: 3931: 3925: 3916: 3899: 3893: 3874: 3868: 3849: 3843: 3825: 3806: 3797: 3791: 3767: 3760: 3725: 3721: 3711: 3676: 3672: 3639: 3632: 3612: 3605: 3594: 3585: 3573: 3562:the original 3549: 3545: 3536: 3528: 3503: 3495: 3471: 3464: 3437: 3433: 3423: 3405: 3398: 3374: 3367: 3343: 3336: 3317: 3311: 3287: 3266:. Retrieved 3255: 3247:the original 3234: 3230: 3224: 3216: 3191: 3187: 3183: 3177: 3165:. Retrieved 3158:the original 3146:(1): 16–22. 3143: 3139: 3133:) nestlings" 3130: 3122: 3089: 3085: 3079: 3044: 3040: 3030: 3019:the original 2990: 2986: 2973: 2928: 2922: 2912: 2901:. Retrieved 2894:the original 2865: 2861: 2848: 2828: 2821: 2802: 2796: 2775: 2766: 2733: 2729: 2694: 2664: 2658: 2649: 2645: 2632: 2623: 2619: 2610: 2602: 2561: 2555: 2536: 2530: 2511: 2505: 2491:(2): 42–50. 2488: 2484: 2478: 2459: 2455: 2415: 2411: 2405: 2380: 2376: 2372: 2366: 2341: 2337: 2324: 2302:(1): 90–98. 2299: 2295: 2291: 2285: 2275: 2268: 2243: 2239: 2226: 2217: 2208: 2189: 2126: 2120: 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: 7715:WikiProject 7625:Piciformes 7508:Australaves 7487:Suliformes 7405:Gruiformes 7260:(flamingos) 7169:Tetraoninae 7140:Phasianidae 7129:Rhynchortyx 7094:Dactylortyx 6961:Megapodidae 6951:Penelopinae 6909:Galliformes 6651:Rheiformes 6645:(ostriches) 6595:individuals 6469:Ornithology 6456:interaction 6211:Preen gland 5930:Ornithology 4807:LiveScience 4658:Development 2383:: 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 7465:(penguins) 7318:(bustards) 7156:Perdicinae 7101:Dendrortyx 7073:Callipepla 7005:Megapodius 6970:Aepypodius 6848:Tadorninae 6830:true geese 6661:(tinamous) 6620:Neornithes 6531:Pheasantry 6506:Aviculture 6274:Incubation 6264:Lek mating 5206:1808/16618 5185:The Condor 5082:: 93–110. 5035:Mallophage 4954:2018-02-18 4896:2019-09-05 4803:"Platypus" 4317:The Condor 4005:The Condor 3268:2010-06-25 2903:2013-10-31 2580:1099968357 2240: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, 7534:(parrots) 7378:(hoatzin) 7329:Strisores 7310:(turacos) 7302:(cuckoos) 7231:(mesites) 7150:(turkeys) 7122:Philortyx 7039:Agelastes 7032:Acryllium 7023:Numididae 7012:Talegalla 6922:gamebirds 6915:landfowls 6894:Anseranas 6858:Anhimidae 6817:Anserinae 6600:fictional 6322:dinosaurs 6317:Theropoda 6304:Evolution 6249:Migration 6231:Behaviour 5902:263166207 5332:Ecography 5266:1600-0706 5215:0010-5422 5145:0962-8452 5045:: 23, 24. 4867:1537-5323 4743:0027-8424 4678:1477-9129 4623:0028-0836 4557:0036-8075 4507:205124061 4479:Evolution 3908:646859135 3188:Behaviour 3106:0003-3472 2609:"Scopate 2588: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 7731:Category 7679:Category 7553:Afroaves 7481:(storks) 7283:Passerea 7268:(grebes) 7204:Columbea 7115:Oreortyx 7087:Cyrtonyx 6977:Alectura 6941:Cracinae 6933:Cracidae 6810:Oxyurini 6800:Aythyini 6795:Anatinae 6779:Anatidae 6526:Falconry 6489:big year 6344:Seabirds 6254:Foraging 6201:Feathers 5860:64013457 5829:21525059 5776:85254980 5733:16 April 5727:Archived 5702:16 April 5597:21323655 5399:12 March 5317:42756257 5309:19628866 5223:32708877 5163:15888414 5002:14825028 4875:10506542 4761:21368127 4694:10925294 4686:12975342 4631:16885984 4573:17226774 4565:15353802 4499:25964090 4339:85776106 4073:20407444 4065:21069752 3835:98001121 3752:19864276 3703:17148356 3415:11031934 3114:53170955 3071:12952627 3015:44030487 2965:20463902 2924:PLoS ONE 2758:86597085 2665:Wildfowl 2432:18430834 2397:38791844 2316:85982302 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 7691:Commons 7195:Neoaves 7080:Colinus 7046:Guttera 6984:Eulipoa 6805:Mergini 6669:(kiwis) 6653:(rheas) 6464:Ringing 6289:Hybrids 6284:Nesting 6239:Singing 6216:Plumage 6191:Dactyly 6161:Anatomy 6151:Outline 6141:: Aves) 5820:3203496 5754:The Auk 5562:6052126 5363:Bibcode 5289:Bibcode 5281:Science 5246:Bibcode 5154:1599863 4994:3273522 4883:4369897 4752:3053969 4721:Bibcode 4639:2416057 4603:Bibcode 4537:Bibcode 4529:Science 4226:5362278 4218:3881820 4047:(PDF). 4025:1367580 3743:2865047 3694:1618910 3546:Seabird 3456:3883510 3208:4535638 3167:27 June 3062:1698012 2995:Bibcode 2956:2865545 2933:Bibcode 2890:1940542 2870:Bibcode 2862:Ecology 2750:4514529 2646:The Auk 2412:The Auk 2358:1366249 2260:1369622 2100:Bibcode 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 7703:Portal 7579:(owls) 7053:Numida 6991:Leipoa 6874:Chauna 6867:Anhima 6562:Genera 6536:Imping 6454:Human 6294:Colony 6221:Vision 6206:Flight 6092: 6073: 6050: 6031: 6012: 5993: 5974: 5955: 5936: 5917: 5900: 5875: 5858: 5827: 5817: 5774: 5669: 5626: 5595: 5560: 5519: 5485: 5452: 5427:6 June 5315: 5307: 5264: 5221: 5213: 5161: 5151: 5143: 5000: 4992: 4881: 4873: 4865: 4759: 4749: 4741: 4692: 4684: 4676: 4637: 4629: 4621: 4595:Nature 4571: 4563: 4555: 4505: 4497: 4456: 4422: 4397: 4366: 4337: 4289: 4255: 4224: 4216: 4173: 4148: 4097: 4071: 4063: 4023: 3938: 3906: 3881: 3856: 3833: 3779: 3750: 3740: 3701: 3691: 3647: 3620: 3516: 3483: 3454: 3413: 3386: 3355: 3324: 3299: 3206: 3112: 3104: 3069: 3059: 3013: 2963: 2953: 2888: 2836: 2809: 2756: 2748: 2701: 2671: 2578: 2568: 2543: 2518: 2430: 2395: 2356: 2338:Condor 2314: 2258: 2196: 2133: 2032: 1988: 1943: 1899:1 July 1890:"Beak" 1872: 1742:, and 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