cere v : wrap us in a cerecloth; "cerecloth a corpse"
- Plural of cera
EtymologyFrom quaerere#Latin, present active infinitive of quaero#Latin
- a ruga
The beak, bill or rostrum is an external anatomical structure of birds which, in addition to eating, is used for grooming, manipulating objects, killing prey, probing for food, courtship and feeding their young. The term also refers to a similar mouthpart in some cephalopods, cetaceans, turtles, Anuran tadpoles and sirens.
AnatomyBeaks can vary significantly in size and shape from species to species. The beak is composed of an upper jaw called the maxilla, and a lower jaw called the mandible. The jaw is made of bone, typically hollow or porous to conserve weight for flying. The outside surface of the beak is covered by a thin horny sheath of keratin called the rhamphotheca. Between the hard outer layer and the bone is a vascular layer containing blood vessels and nerve endings. The rhamphotheca also includes the knob which is found above the beak of some swans, such as the Mute Swan, and some domesticated Chinese geese (pictured).
The beak has two holes called nares (nostrils) which connect to the hollow inner beak and thence to the respiratory system. The nares are usually located directly above the beak. In some birds, they are located in a fleshy, often waxy structure at the base of the beak called the cere (from Latin cera). Hawks, parrots, doves, skuas and budgerigars are among the birds that have ceres. Budgerigars are dimorphic in that the males' ceres turn bright blue upon maturity, while the females' ceres turn tan. The female budgies' ceres also appear wrinkled, to a greater extent during periods of fertility. Immature budgies have pale pinkish ceres which are smooth and shiny.
On some birds, the tip of the beak is hard, dead tissue used for heavy-duty tasks such as cracking nuts or killing prey. On other birds, such as ducks, the tip of the bill is sensitive and contains nerves, for locating things by touch. The beak is worn down by use, so it grows continuously throughout the bird's life.
Unlike jaws with teeth, beaks are not used for chewing. Birds swallow their food whole, which is broken up in the gizzard.
In the mallard, and perhaps in other ducks, there is no cere, and the nostrils are in the hard part of the beak, as a soft cere would be liable to injury when the duck dredges for food among submerged debris and stones.
During courtship, mated pairs of a variety of bird species touch and clasp each other's bills. This is called billing, and appears to strengthen the pair bond (Terres, 1980). Gannets raise their bills high and repeatedly clatter them (pictured); 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".
TerminologyThe term decurved refers to a downward curving beak.
- Gilbertson, Lance; Zoology Lab Manual; McGraw Hill Companies, New York; ISBN 0-07-237716-X (fourth edition, 1999)
- Terres, John. K. The Audubon Society Encyclopedia of North American Birds, New York: Alfred A. Knopf, 1980. ISBN 0-394-46651-9
cere in Catalan: Bec
cere in Czech: Zobák
cere in Danish: Næb
cere in German: Schnabel
cere in Spanish: Pico (zoología)
cere in Esperanto: Beko
cere in French: Bec
cere in Western Frisian: Snaffel
cere in Korean: 부리
cere in Croatian: Kljun
cere in Italian: Becco
cere in Hebrew: מקור
cere in Georgian: ნისკარტი
cere in Latin: Rostrum (beccus)
cere in Lithuanian: Snapas
cere in Hungarian: Csőr
cere in Dutch: Snavel
cere in Japanese: くちばし
cere in Norwegian: Nebb
cere in Norwegian Nynorsk: Nebb
cere in Occitan (post 1500): Bèc
cere in Polish: Dziób (zoologia)
cere in Portuguese: Bico
cere in Quechua: Chhukruna
cere in Russian: Клюв
cere in Sicilian: Pizzu (mascidda)
cere in Simple English: Beak
cere in Slovak: Zobák
cere in Finnish: Nokka
cere in Swedish: Näbb
cere in Turkish: Kuş gagası
cere in Ukrainian: Дзьоб
cere in Chinese: 喙