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  • Glossary
| Last Updated:08/04/2020



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Term applied to coloration important in aerial display

Aspect ratio

In birds, the ratio of wing length to wing breadth

Alternate plumage

The spring plumage which is also referred to as the breeding plumage; the basic plumage is the plumage the bird has during the winter or the non-breeding time.


A special physical or behavioral ability that has allowed a species adjust to a particular way of life.


having a protective role applied particularly to coloration. 'Proaposematic'means that the protection is in the form of a warning (e.g. of unpalatability) ; 'pseudaposematic 'means that the warning is a bluff (protective mimicry) ; 'synaposematic' means that the warning signal is shared in common with other species.


the community of birds (species) found in a given region


Preening of one individual (usually of head plumage)by another; offen serves to strengthen pair bond.


Bunch of ornamental plumes over the breast and back of some speciesof egrets seen during the breeding season


refers to species occurring in geographically seperated areas, i.e. range not overlapping


Term for a vesicle, among other things the dilated end of a semicircular canal in the labryinth of the ear


Without olfactory sense (smell blind)


A paired bone of the lower jaw

Applide ornithology

The application of ornithological knowledge to human activities concerned with birds

Alular quills

Three feathers attached to the alula originating from the base of the primaries. They are essential for low speed flight and aid in coordinated landing and take-off

Alar bar

Wing bar formed by upperwing-coverts if different in colourfrom surrounding feathers, as in some frigatebirds

Altitudinal distribution

Distribution in accordance with height above sea-level in a particular area


Structure adaptively similar to another but of basically different nature

Amniotic closure

Term for the protective sealing of the eyes and ears during the first few days of life in some birds, the function being analogous to that earlier performed for the embryo by the amnion


Term applied to the practice of keeping birds of wild species in aviaries or enclosures, with the object of studying their habits and, if possible, inducing them to breed successfully under conditions as nearly as practicable approaching those found in nature; an educational purpose is also served when the birds are exhibited to the public in zoological gardens


Young that are helpless for a substantial period affer hatching


tree-dwelling (may also frequent bushes)

Altitudinal migrant

A species fround at different altitudes at different times of the year, especially breeding higher in the mountains and wintering lower down


Ear-coverts, cheek


Abnormal absence of pigment causing white areasin plumage; full albinos are all white with pink eyes and soft parts


A collective noun for a number of birds (or other animals) of one kind together; some of these words are of general application, while others have restricted meanings.The usual term for an assemblage of birds is 'flock'; sometimes 'flight' if they are on the wing; sometimes 'party' if the number is quite small. Other ordinary English words can of course be used for descriptive purposes in appropriate circumstances, e.g. 'assemblage', 'congregation', 'multitude', 'horde', 'host', and (on the water) 'raft'. The word 'brood' is used for the chicks or nestlings hatched from a 'clutch' or 'set' of eggs laid by one hen bird for simultaneous incubation. Birds breeding gregariously are referred to as a 'colony'. 'Pair' means a male and a female, presumably united. 'Brace' means two birds, usually dead-a measure used in counting the sportsman's 'bag' .


the feathers in the armpit at the base of the underwing

Antiphonal duetting

Alternate singing, usually by members of a pair


pertaining to birds

Alarm Call

A call expresses by a wild bird to signal danger

Activity Range

The area over which a bird regularly carries on its affairs.


Inner wing, part of wing from carpal joint inward, including secondariesand their coverts


Numbering system for primaries, from outermost to innermost(opposite of descendant)


Terminal; refers to the apex or outer end


living or groing on or in water


Pertaining to the elbow; sometime used with refference to the whole dorsal surface of the wing

Antiphonal song



An area of skin from which no feathers grow


The bird-life of an area


change of colour (hypothetical) in a fully developed feather


Small group of feathers attached to carpal joint, overlying primarycoverts

Abdominal air sacs

A pair of air sacs in the abdominal region of birds that may have connections into the bones of the pelvis and femur; their position within the abdominal cavity may shift during the day to maintain the bird’s streamlined shape during digestion and egg laying

Anting (passive)

 Positioning oneself among a swarm of ants, permitting them to run all over the body and to move in and out among the feathers, presumably to deter ectoparasites

  Open Video

Anting (active)

 Picking up an ant or other chemically potent object, such as a millipede, and deliberately rubbing it in the feathers—presumably to deter ectoparasites

 Open Video

Age-specific survival rate

 The proportion of individuals in a particular age group in a population that survive a particular interval of time—usually a year

Adherent cup nest

 A cup nest made of mud or saliva that relies on chemical forces to hold it to a vertical surface; built by many swifts, including the Edible-nest Swiftlets of Southeast Asia, whose nests are used in the Asian delicacy bird’s-nest soup


 The changes in the curvature of the lens (and cornea, in birds) of the eye brought about by the action of the ciliary muscles. These changes allow the eye to focus on objects at different distances.


 Adventitious concealing coloration, as distinct from ‘cryptic’ coloration adapted to the purpose


 Describes young birds that hatch undeveloped and in many cases naked or with sparse down; such help­less young require complete parental care

Arrested moult

The situation where the progress of a bird's moult is suspended for a period, to be resumed later. An example of a species which normally arrests its moult is the Common TernSterna hirundo, which begins its moult prior to the autumn migration, suspends it during the migration itself and then continues to moult after arrival in its winter quarters

Allen’s rule

 That among the forms of a polytypic species, extensions of the body (in birds, chiefly bill) tend to be longer in the warmer parts of the total range and shorter in the cooler parts. It is generally accepted that the adaptive basis for this rule is reduction of heat loss in cold climates

Asynchronous hatching

 The situation in which all the eggs in a clutch do not hatch at (more or less) the same time, as is more usual among birds, but have their hatching spread over several days. It is well seen in the various types of raptor, and is an adaptation to a type of food supply which may fluctuate. During seasons when food is short the later hatched young will probably starve as the earlier hatched young, being larger and stronger, deprive them of food, and so the size of the brood is reduced to a level in balance with the available food supply. In years of plenty all the young may be able to survive. In 'synchronous hatching' all the eggs hatch at more or less the same time