The beak, bill, and/or rostrum is an external anatomical structure of birds that is used for eating and for preening, manipulating objects, killing prey, fighting, probing for food, courtship and feeding young. The terms beak and rostrum are also used to refer to a similar mouth part in some ornithischians, pterosaurs, turtles, cetaceans, dicynodonts, anuran tadpoles, monotremes (i.e. echidnas and platypuses, which have a beak-like structure), sirens, pufferfish, billfishes and cephalopods.
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 known as nares lead to the respiratory system.
Although the word beak was, in the past, generally restricted to the sharpened bills of birds of prey, in modern ornithology, the terms beak and bill are generally considered to be synonymous. The word, which dates from the 13th century, comes from the Middle English bec, which itself comes from the Latin beccus.
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 upper mandible (or maxilla) and lower mandible (or mandible). The upper, and in some cases the lower, mandibles are strengthened internally by a complex three-dimensional network of bony spicules (or trabeculae) seated in soft connective tissue and surrounded by the hard outer layers of the beak. The avian jaw apparatus is made up of two units: one four-bar linkage mechanism and one five-bar linkage mechanism.
The upper mandible is supported by a three-pronged bone 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 skull. 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 upwards and downwards.
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 ratites. Here, the vomer 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.
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 rami), which can be U-shaped or V-shaped, join distally (the exact location of the joint depends on the species) but are separated proximally, 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 Huia, which have well-developed digastric muscles 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.
The outer surface of the beak consists of a thin horny sheath of keratin called the rhamphotheca, which can be subdivided into the rhinotheca of the upper mandible and the gnathotheca of the lower mandible. This covering arises from the Malpighian layer of the bird's epidermis, growing from plates at the base of each mandible. There is a vascular layer between the rhamphotheca and the deeper layers of the dermis, which is attached directly to the periosteum of the bones of the beak. The rhamphotheca grows continuously in most birds, and in some species, the color varies seasonally. In some alcids, 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.
While most extant birds have a single seamless rhamphotheca, species in a few families, including the albatrosses and the emu, 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.
The tomia (singular tomium) 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. Granivorous (seed-eating) birds, for example, have ridges in their tomia, which help the bird to slice through a seed's outer hull. Most falcons 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 kites, principally those that prey on insects or lizards, also have one or more of these sharp projections, as do the shrikes. Some fish-eating species, e.g., the mergansers, have sawtooth serrations along their tomia, which help them to keep hold of their slippery, wriggling prey.
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 insectivores (preferring hard-shelled prey) or snail eaters, and the brush-like projections may help to increase the coefficient of friction between the mandibles, thereby improving the bird's ability to hold hard prey items. Serrations on hummingbird 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 nectar thieves, as they can more effectively hold and cut through long or waxy flower corollas. In some cases, the color of a bird's tomia can help to distinguish between similar species. The snow goose, for example, has a reddish-pink bill with black tomia, while the whole beak of the similar Ross's goose is pinkish-red, without darker tomia.
The culmen is the dorsal ridge of the upper mandible. Likened by ornithologist Elliott Coues 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 bird banding (ringing) 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 raptors and owls)—and scientists from various parts of the world generally favor one method over another. In all cases, these are chord measurements (measured in a straight line from point to point, ignoring any curve in the culmen) taken with calipers.
The shape or color of the culmen can also help with the identification of birds in the field. For example, the culmen of the parrot crossbill is strongly decurved, while that of the very similar red crossbill is more moderately curved. The culmen of a juvenile common loon is all dark, while that of the very similarly plumaged juvenile yellow-billed loon is pale towards the tip.
The gonys is the ventral 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 gonydeal angle or gonydeal expansion. 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 gonydeal spot near the gonydeal expansion. This spot triggers begging behavior in gull chicks. The chick pecks at the spot on its parent's bill, which in turn stimulates the parent to regurgitate food.
Depending on its usage, commissure 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.
In bird anatomy, the gape is the interior of the open mouth of a bird, and the gape flange is the region where the two mandibles join together at the base of the beak. The width of the gape can be a factor in the choice of food.
Gapes of juvenile altricial 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 families Viduidae and Estrildidae, 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 passerine species found that the gapes were conspicuous in the ultraviolet 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.
Red gape color has been shown in several experiments to induce feeding. An experiment in manipulating brood size and immune system with barn swallow nestlings showed the vividness of the gape was positively correlated with T-cell–mediated immunocompetence, and that larger brood size and injection with an antigen led to a less vivid gape. Conversely, the red gape of the common cuckoo (Cuculus canorus) did not induce extra feeding in host parents. Some brood parasites, such as the Hodgson's hawk-cuckoo (C. fugax), have colored patches on the wing that mimic the gape color of the parasitized species.
When born, the chick's gape flanges are fleshy. As it grows into a fledgling, 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.
Most species of birds have external nares (nostrils) located somewhere on their beak. The nares are two holes—circular, oval or slit-like in shape—which lead to the nasal cavities within the bird's skull, and thus to the rest of the respiratory system. In most bird species, the nares are located in the basal third of the upper mandible. Kiwis are a notable exception; their nares are located at the tip of their bills. A handful of species have no external nares. Cormorants and darters have primitive external nares as nestlings, but these close soon after the birds fledge; adults of these species (and gannets and boobies of all ages, which also lack external nostrils) breathe through their mouths. There is typically a septum 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 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.
Species in the bird order Procellariformes 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 falcons, have a small bony tubercule 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 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.
The nares of some birds are covered by an operculum (plural opercula), a membraneous, horny or cartilaginous 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 Attagis seedsnipe help to keep dust out. The nares of nestling tawny frogmouths 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 as the birds age, disappearing completely by the time they reach adulthood. In pigeons, 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 cere, this is a different structure. Tapaculos are the only birds able to move their opercula.
Birds from a handful of families—including raptors, owls, skuas, parrots, turkeys and curassows—have a waxy structure called a cere (from the Latin cera, which means "wax") or ceroma which covers the base of their bill. This structure typically contains the nares, except in the owls, where the nares are distal 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 Montague's harrier's cere, for example, correlates to its body mass and physical condition. The cere color of young Eurasian scops-owls has an ultraviolet (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 wavelength 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.
The color or appearance of the cere can be used to distinguish between males and females in some species. For example, the male great curassow has a yellow cere, which the female (and young males) lack. The male budgerigar's cere is blue, while the female's is pinkish or brown.
All birds of the family Anatidae (ducks, geese, and swans) have a nail, a plate of hard horny tissue at the tip of the beak. This shield-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 diving ducks use theirs to pry molluscs from rocks. There is evidence that the nail may help a bird to grasp things; 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 mechanoreceptors, nerve cells that are sensitive to pressure, vibration or touch, are located under the nail.
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 greater scaup has a wider black nail than does the very similar lesser scaup. Juvenile "grey geese" have dark nails, while most adults have pale nails. The nail gave the wildfowl family one of its former names: "Unguirostres" comes from the Latin ungus, meaning "nail" and rostrum, meaning "beak".
Rictal bristles are stiff hair-like feathers that arise around the base of the beak. They are common among insectivorous 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 empirical evidence 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 vegetation. There is also evidence that the rictal bristles of some species may function tactilely, in a manner similar to that of mammalian whiskers (vibrissae). Studies have shown that Herbst corpuscles, 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.
Full-term chicks of most bird species have a small sharp, calcified projection on their beak, which they use to chip their way out of their egg. 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 tooth, as the similarly-named projections of some reptiles are; instead, it is part of the integumentary system, as are claws and scales. 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. 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. Megapode chicks have an egg tooth while still in the egg but lose it before hatching, while kiwi 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 petrels keep theirs for nearly three weeks and marbled murrelets have theirs for up to a month. Generally, the egg tooth drops off, though in songbirds it is reabsorbed.
The color of a bird's beak results from concentrations of pigments—primarily melanins and carotenoids—in the epidermal layers, including the rhamphotheca. Eumelanin, 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. Phaeomelanin 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 responsible for the coloration of most red, orange, and yellow beaks. The hue of the color is determined by the precise mix of red and yellow pigments, while the saturation 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 concentrations. Beak coloration helps to make displays using those beaks more obvious.
Birds are capable of seeing colors in the ultraviolet 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. King and emperor penguins, 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 conspecifics. For instance, the very similarly-plumaged king and emperor penguins have UV-reflective spots in different positions on their beaks.
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 intraspecific competition. For example, females of nearly all shorebirds have longer bills than males of the same species, and female American avocets 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 hornbills show sexual dimorphism in the size and shape of both beaks and casques, and the female huia's slim, decurved bill was nearly twice as long as the male's straight, thicker one.
Color can also differ between sexes or ages within a species. Typically, such a color difference is due to the presence of androgens. For example, in house sparrows, melanins are produced only in the presence of testosterone; castrated male house sparrows—like female house sparrows—have brown beaks. Castration also prevents the normal seasonal color change in the beaks of male black-headed gulls and indigo buntings.
Birds may bite or stab with their beaks to defend themselves. Some species use their beaks in displays of various sorts. As part of his courtship, for example, the male garganey touches his beak to the blue speculum feathers on his wings in a fake preening display, and the male Mandarin duck 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. The platypus uses its bill to navigate underwater, detect food, and dig. 
The beak of birds plays a role in removing skin parasites (ectoparasites) 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.
This overhang of the beak is thought to be under stabilising natural selection. 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.
Additionally, because of the role beaks play in preening, this is evidence for coevolution 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 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.
Studies have shown that some birds use their beaks to rid themselves of excess heat. The toco toucan, which has the largest beak relative to the size of its body of any bird species, is capable of modifying the blood flow to its beak. This process allows the beak to work as a "transient thermal radiator", reportedly rivaling an elephant's ears in its ability to radiate body heat. Measurements of the bill sizes of several species of American sparrows found in salt marshes along the North American coastlines show a strong correlation with summer temperatures recorded in the locations where the sparrows breed; latitude 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 ratites, including the common ostrich, the emu and the southern cassowary, 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.
During courtship, mated pairs of many bird species touch or clasp each other's bills. Termed billing (also nebbing in British English), this behavior appears to strengthen pair bonding. 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.
Gannets raise their bills high and repeatedly clatter them, the male puffin nibbles at the female's beak, the male waxwing puts his bill in the female's mouth and ravens hold each other's beaks in a prolonged "kiss". Billing can also be used as a gesture of appeasement or subordination. Subordinate gray jay routinely bill more dominant birds, lowering their body and quivering their wings in the manner of a young bird food begging as they do so. A number of parasites, including rhinonyssids and Trichomonas gallinae are known to be transferred between birds during episodes of billing.
Usage of the term has spread beyond avian behavior; "billing and cooing" in reference to human courtship (particularly kissing) has been in use since Shakespeare's time, and derives from the courtship of doves.
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 poultry flocks, particularly laying and broiler breeder flocks, because it helps reduce the damage the flocks inflict on themselves due to a number of stress-induced behaviors, including cannibalism, vent pecking and feather pecking. 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 neuromas 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 adrenal glands weigh less, and their plasma corticosterone levels are lower than those found in untrimmed poultry, indicating that they are less stressed overall.
A similar but separate practice, usually performed by an avian veterinarian 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. Amongst raptor keepers, this practice is commonly known as "coping".
The bill tip organ 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 corpuscles of Herbst. 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' includes members of ibisis, shorebirds of the family Scolopacidae, and kiwis.
There is a suggestion that across these species, the bill tip organ is more well 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 parrots, who are known for their dextrous extractive foraging techniques. Unlike probing foragers, the tactile pits in parrots are embedded in the hard keratin (or rhamphotheca) 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.
An aquiline nose (also called a Roman nose or hook nose) is a human nose with a prominent bridge, giving it the appearance of being curved or slightly bent. The word aquiline comes from the Latin word aquilinus ("eagle-like"), an allusion to the curved beak of an eagle. While some have ascribed the aquiline nose to specific ethnic, racial, or geographic groups, and in some cases associated it with other supposed non-physical characteristics (e.g., intelligence, status, personality, etc., see below), no scientific studies or evidence support any such linkage. As with many other phenotypical expressions (e.g., "widow's peak", eye color, earwax type) it is found in many geographically diverse populations.Barnell Bohusk
Barnell Bohusk, currently known as Blackwing, formerly known as Beak, is a fictional character, a superhero appearing in American comic books published by Marvel Comics. The character is usually depicted as being associated with the X-Men and its spinoff the Exiles. Beak first appeared in New X-Men #117 and was created by Grant Morrison and Ethan Van Sciver.Bec de corbin
A bec de corbin is a type of pole weapon and war hammer that was popular in medieval Europe. The name is Old French for "raven's beak" or "beak of the crow". Similar to the Lucerne hammer, it consists of a modified hammer's head and spike mounted atop a long pole. Unlike the Lucerne hammer, the bec de corbin was used primarily with the "beak" or fluke to attack instead of the hammer head. The hammer face balancing the beak was often blunt instead of the multi-pronged Lucerne, and the beak tended to be stouter; better designed for tearing into thinner plate armor, mail or padded jacks. The spike mounted on the top of the head was also not nearly as long and thin as in the Lucerne. "Bec de corbin" occasionally becomes a catchall for any type of warhammer, such as a maul or a horseman's pick.
A similar name, bec de faucon (meaning "falcon's beak"), refers to a related weapon called a pollaxe or, more specifically, to the hook on its reverse side.Bird anatomy
Bird anatomy, or the physiological structure of birds' bodies, shows many unique adaptations, mostly aiding flight. Birds have a light skeletal system and light but powerful musculature which, along with circulatory and respiratory systems capable of very high metabolic rates and oxygen supply, permit the bird to fly. The development of a beak has led to evolution of a specially adapted digestive system. These anatomical specializations have earned birds their own class in the vertebrate phylum.Cephalopod beak
All extant cephalopods have a two-part beak, or rostrum, situated in the buccal mass and surrounded by the muscular head appendages. The dorsal (upper) mandible fits into the ventral (lower) mandible and together they function in a scissor-like fashion. The beak may also be referred to as the mandibles or jaws.Fossilised remains of beaks are known from a number of cephalopod groups, both extant and extinct, including squids, octopuses, belemnites, and vampyromorphs. Aptychi – paired plate-like structures found in ammonites – may also have been jaw elements.Cloaca
In animal anatomy, a cloaca kloh-AY-kə (plural cloacae kloh-AY-see or kloh-AY-kee) is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals, opening at the vent. All amphibians, birds, reptiles, and a few mammals (monotremes, tenrecs, golden moles, and marsupial moles) have this orifice, from which they excrete both urine and feces; this is in contrast to most placental mammals, which have two or three separate orifices for evacuation. Excretory openings with analogous purpose in some invertebrates are also sometimes referred to as cloacae. Mating by cloaca is known as cloacal copulation, mostly referred to as cloacal kiss.
The cloacal region is also often associated with a secretory organ, the cloacal gland, which has been implicated in the scent-marking behavior of some reptiles, marsupials, amphibians, and monotremes.Darwin's finches
Darwin's finches (also known as the Galápagos finches) are a group of about fifteen species of passerine birds. They are well known for their remarkable diversity in beak form and function. They are often classified as the subfamily Geospizinae or tribe Geospizini. They belong to the tanager family and are not closely related to the true finches. The closest known relative of the Galápagos finches is South-American Tiaris obscurus. They were first collected by Charles Darwin on the Galápagos Islands during the second voyage of the Beagle. Apart from the Cocos finch, which is from Cocos Island, the others are found only on the Galápagos Islands.
The term "Darwin's finches" was first applied by Percy Lowe in 1936, and popularised in 1947 by David Lack in his book Darwin's Finches. Lack based his analysis on the large collection of museum specimens collected by the 1905–06 Galápagos expedition of the California Academy of Sciences, to whom Lack dedicated his 1947 book. The birds vary in size from 10 to 20 cm and weigh between 8 and 38 grams. The smallest are the warbler-finches and the largest is the vegetarian finch. The most important differences between species are in the size and shape of their beaks, which are highly adapted to different food sources. The birds are all dull-coloured.
A long term study carried out for more than 40 years by the Princeton University researchers Peter and Rosemary Grant has documented evolutionary changes in beak size affected by El Niño/La Niña cycles in the Pacific.Debeaking
Debeaking is the partial removal of the beak of poultry, especially layer hens and turkeys although it may also be performed on quail and ducks. Most commonly, the beak is shortened permanently, although regrowth can occur. The trimmed lower beak is somewhat longer than the upper beak.
Beak trimming is most common in egg-laying strains of chickens. In some countries, such as the United States, turkeys routinely have their beaks trimmed. In the UK, only 10% of turkeys are beak trimmed. Beak trimming is a preventive measure to reduce damage caused by injurious pecking such as cannibalism, feather pecking and vent pecking, and thereby improve livability. Commercial broiler chickens are not routinely beak trimmed as they reach slaughter weight at approximately 6 weeks of age, i.e. before injurious pecking usually begins. However, broiler breeding stock may be trimmed to prevent damage during mating. In some countries, beak trimming is done as a last resort where alternatives are considered not to be possible or appropriate.
Opponents of beak trimming state that the practice reduces problem pecking by minor amounts compared to the trauma, injury, and harm done to the entire flock by beak trimming. Reduction is in single digit percentiles, whereas improvement of conditions especially in layer colonies will cease problematic behavior entirely.Beak trimming has been banned in Switzerland since 1992 and has been phased out in Germany in 2017.In close confinement, cannibalism, feather pecking and aggression are common among turkeys, ducks, pheasants, quail, and chickens of many breeds (including both heritage breeds and modern hybrids) kept for eggs. The tendency to cannibalism and feather pecking varies among different strains of chickens, but does not manifest itself consistently. Some flocks of the same breed may be entirely free from cannibalism, while others, under the same management, may have a serious outbreak. Mortalities, mainly due to cannibalism, can be up to 15% in egg laying flocks housed in aviaries, straw yards, and free-range systems.Because egg laying strains of chickens can be kept in smaller group sizes in caged systems, cannibalism is reduced leading to a lowered trend in mortality as compared to non-cage systems. Cannibalism among flocks is highly variable and when it is not problematic, then mortalities among production systems are similar.Grosbeak
Grosbeak is a form taxon containing various species of seed-eating passerine birds with large beaks. Although they all belong to the superfamily Passeroidea, these birds are not part of a natural group but rather a polyphyletic assemblage of distantly related songbirds. Some are cardueline finches in the family Fringillidae, while others are cardinals in the family Cardinalidae; one is a member of the weaver family Ploceidae. The word "grosbeak", first applied in the late 1670s, is a partial translation of the French grosbec, where gros means "large" and bec means "beak".The following is a list of grosbeak species, arranged in groups of closely related genera. These genera are more closely related to smaller-billed birds than to other grosbeaks. The single exception are the three genera of "typical grosbeak finches", which form a group of closest living relatives and might thus be considered the "true" grosbeaks.Northern cardinal
The northern cardinal (Cardinalis cardinalis) is a bird in the genus Cardinalis; it is also known colloquially as the redbird, common cardinal or just cardinal (which was its name prior to 1985). It can be found in southern eastern Canada, through the eastern United States from Maine to Minnesota to Texas, and south through Mexico, Belize, Guatemala and Big Island of Hawai’i. Its habitat includes woodlands, gardens, shrublands, and wetlands.
The northern cardinal is a mid-sized songbird with a body length of 21–23 cm (8.3–9.1 in). It has a distinctive crest on the head and a mask on the face which is black in the male and gray in the female. The male is a vibrant red, while the female is a reddish olive color. The northern cardinal is mainly granivorous, but also feeds on insects and fruit. The male behaves territorially, marking out his territory with song. During courtship, the male feeds seed to the female beak-to-beak. A clutch of three to four eggs is laid, and two to four clutches are produced each year. It was once prized as a pet, but its sale as a cage bird was banned in the United States by the Migratory Bird Treaty Act of 1918.Pico de gallo
In Mexican cuisine, pico de gallo (Spanish pronunciation: [ˈpiko ðe ˈɣaʎo], lit. beak of rooster), also called salsa fresca or salsa cruda, is traditionally made from chopped tomato, onion, and cilantro, with lime juice mixed in.
Pico de gallo can be used in much the same way as other Mexican liquid salsas, but since it contains less liquid, it can also be used as a main ingredient in dishes such as tacos and fajitas.
The tomato-based variety is widely known as salsa picada (minced/chopped sauce). In Mexico it is normally called salsa mexicana (Mexican sauce). Because the colours of the red tomato, white onion, green chili and cilantro are reminiscent of the colours of the Mexican flag, it is also sometimes called salsa bandera (flag sauce).
In many regions of Mexico the term refers to any of a variety of salads (including fruit salads), salsa, or fillings made with tomato, tomatillo, avocado, orange, jícama, cucumber, papaya, or mild chilis. The ingredients are tossed in lime juice and optionally with either hot sauce or chamoy, then sprinkled with a salty chili powder.Plague doctor
A plague doctor was a medical physician who treated victims of the bubonic plague. In times of epidemics, such physicians were specifically hired by towns where the plague had taken hold. Since the city was paying their salary, they treated everyone: both the wealthy and the poor. However, some plague doctors were known to charge patients and their families additional fees for special treatments or false cures. Typically they were not professionally trained nor experienced physicians or surgeons, but rather they were often either second-rate doctors unable to otherwise run a successful medical practice or young physicians seeking to establish themselves. These doctors rarely cured their patients; rather, they served to record a count of the number of people contaminated for demographic purposes.
Plague doctors by their covenant treated plague patients and were known as municipal or "community plague doctors", whereas "general practitioners" were separate doctors and both might be in the same European city or town at the same time. In France and the Netherlands, plague doctors often lacked medical training and were referred to as "empirics". In one case, a plague doctor had been a fruit salesman before his employment as a physician.In the 17th, 18th, and 19th centuries, some doctors wore a beak-like mask which was filled with aromatic items. The masks were designed to protect them from putrid air, which (according to the miasmatic theory of disease) was seen as the cause of infection. The design of these clothes has been attributed to Charles de Lorme, the chief physician to Louis XIII.Plague doctor costume
The clothing worn by plague doctors was intended to protect them from airborne diseases. The costume, used in France and Italy in the 17th century, consisted of an ankle length overcoat and a bird-like beak mask, often filled with sweet or strong smelling substances (commonly lavender), along with gloves, boots, a wide-brimmed hat, and an outer over-clothing garment.Poultry farming
Poultry farming is the process of raising domesticated birds such as chickens, ducks, turkeys and geese for the purpose of farming meat or eggs for food. Poultry – mostly chickens – are farmed in great numbers. Farmers raise more than 50 billion chickens annually as a source of food, both for their meat and for their eggs. Chickens raised for eggs are usually called layers while chickens raised for meat are often called broilers.In the United States, the national organization overseeing poultry production is the Food and Drug Administration (FDA). In the UK, the national organisation is the Department for Environment, Food and Rural Affairs (Defra).Puffin
Puffins are any of three small species of alcids (auks) in the bird genus Fratercula with a brightly coloured beak during the breeding season. These are pelagic seabirds that feed primarily by diving in the water. They breed in large colonies on coastal cliffs or offshore islands, nesting in crevices among rocks or in burrows in the soil. Two species, the tufted puffin and horned puffin, are found in the North Pacific Ocean, while the Atlantic puffin is found in the North Atlantic Ocean.
All puffin species have predominantly black or black and white plumage, a stocky build, and large beaks. They shed the colourful outer parts of their bills after the breeding season, leaving a smaller and duller beak. Their short wings are adapted for swimming with a flying technique under water. In the air, they beat their wings rapidly (up to 400 times per minute) in swift flight, often flying low over the ocean's surface.
A significant decline in numbers of puffins on Shetland is worrying scientists.Rhynchospora
Rhynchospora (beak-rush or beak-sedge) is a genus of about 400 species of sedges with a cosmopolitan distribution. The genus includes both annual and perennial species, mostly with erect 3-sided stems and 3-ranked leaves. The achenes bear a beak-like tubercule (hence the name “beak-rush”, although the plants are sedges, not rushes) and are sometimes subtended by bristles. Many of the species are similar in vegetative appearance, and mature fruits are needed to make a positive identification.
The infloresences (spikelets) are sometimes subtended by bracts which can be leaf-like or showy.Rostrum (anatomy)
In anatomy, the term rostrum (from the Latin rostrum meaning beak) is used for a number of phylogenetically unrelated structures in different groups of animals.The Beak of the Finch
The Beak of the Finch: A Story of Evolution in Our Time (ISBN 0-679-40003-6) is a 1994 nonfiction book about evolutionary biology, written by Jonathan Weiner. It won the 1995 Pulitzer Prize for General Non-Fiction. In 2014, a substantially unchanged 20th-anniversary edition e-book was issued with a preface by the author.