From Opus

This section is aimed at explaining the bird and biology specific vocabulary you are likely to meet in other threads in Birdforum.

This page is divided into four sections: Dictionary A-F, Dictionary G-L, Dictionary M-S and Dictionary T-Z.

[edit] A

Allopatric: word used to describe that two populations (often species or subspecies) have non-overlapping ranges.

Alternate plumage: usually synonymous with breeding plumage (nuptial plumage). In most non-tropical species, this plumage is worn during spring and summer, but in Anas ducks, northern hemisphere male ducks will wear this plumage during winter to late spring. Some species have only one annual molt and really show only one plumage year round; if so, they are going to be considered to be in basic plumage (which see) year round. In some birds, the change from basic to alternate plumage is the result of wearing off disguising feather tips to reveal inner more strongly patterned feather parts instead of partial or complete moult leading to alternate plumage.

Alula: see Wings

Auriculars: see Heads

Axillaries: the feathers found in the armpit of a bird when seen from below. These are sometimes important for correct identification, for example in American Wigeon and Grey Plover. See Wings

[edit] B

Bare parts: in bird descriptions, a collective designation for legs, bill, cere, and if applicable, of other bare skin areas such as bare skin around the eyes in for example Bare-crowned Antbird

Basic plumage: mostly synonymous with non-breeding plumage (non-nuptial plumage). In most non-tropical species this is the plumage worn during winters, but in Anas ducks, this is named the Eclipse plumage (which see) and is worn in summer and fall. Opposite is Alternate plumage.

Bristles: see Heads

[edit] C

Cere: see Heads

Clinal variation, Cline: variation within one taxonomic unit (either species or subspecies) that is correlated with geography, so that for example birds living in colder climates are larger than members of the same species living in a warmer climate (many species, Bergmans's rule) or north-eastern birds are brighter colored than south-western (e.g., Chestnut Woodpecker). The important part of this concept is that the shift from one type to another is gradual, not abrupt.

Crepuscular: about a bird that is more active at dawn and dusk than at other times of the day or night. See also diurnal and nocturnal.

Culmen: see Beak

CY = calender year: one of the systems used to tell the age of a bird. In this system, a bird is 1cy from the day it hatches until midnight, December 31, it is 2cy (second calender year) for the next 12 month, etc. In some ways this is more intuitive than a system like "first summer" (see this), but is also has some disadvantages: the switch in designation is not coupled to moult, so to give a description of a photo, one would have to know the date at which it was taken.

[edit] D

Diffraction: structural colors that are produced by the light being reflected in different directions depending on color or some being reflected while other colors of light is allowed to pass through the surface of a structure such as a feather. A feather producing colors due to diffraction does not contain any pigment and in low intensity, diffuse light will look black.
-Iridescence is very similar except that the color produced changes with the angle to the light source.

Diurnal: about a bird that is active during daytime. The activity pattern a bird shows at one time of the year might not hold true at other times of the year; for example, old world warblers have diurnal feeding habits but many species migrate at night.

[edit] E

Eclipse plumage: the non-breeding plumage of male dabbling ducks that looks very similar to female plumage. The eclipse plumage is often replaced by the next breeding plumage well before winter is over, so that the male duck can have attracted the attention of a female before breeding season starts. A similar switch into a non-breeding plumage of brightly colored birds are also known for other groups, including some shorebirds (Ruff and Phalaropes), Sunbirds, Fairywrens, and Weavers.

Endemic (there are two usages of this term):

• 1: a species or other taxon which is only found within the geographic area described; can be a continent (Pavonine Quetzal is found in several countries in South America but not outside), country (Happy Wren is found in several states in Mexico), state (Yellow-billed Magpie is only found in California) or island (Barbuda Warbler is only found on the island of Barbuda).
• 2: an infection, parasite or similar (normally not causing significant consequences) that is persistent in a population such that a percentage of all birds (or other animals) at any given time does carry that infection

Established population: a population that is self-maintaining, not relying on input from the outside to maintain itself. This expression is most often used in the context of a feral population that only becomes tickable if it becomes established (no longer requires continued addition of birds through released or escaped individuals).

[edit] F

Feral population, feral: a population that originated through release/escape of domesticated birds, such as the populations of Rose-ringed Parakeet outside their native range. A feral bird is one that originates in such a feral population.

First Adult Summer: This term does not indicate the age of a bird, it merely indicates that the bird is in its first adult summer plumage. In smaller birds, it is usually moulted into during the year after hatching (when the bird is in second CY), however with many large birds (for example gulls, eagles, albatrosses) this may be up to 3-5 years after hatching. Normally the bird moults into this plumage from first winter plumage. Also known as first breeding plumage, first alternate plumage, or first nuptial plumage. Some species are able to (or at least can attempt to) breed before they reach the full adult plumage.

First Summer (there are two usages of this term):

• 1: synonymous with First Adult Summer
  
• 2: the plumage a bird is wearing in the summer of its second calender year (see CY). For a female passerine, this is probably indistinguishable from full adult plumage, some male passerines the same (others take one additional year), but for gulls, eagles, and several other groups, this is one of several immature plumages.

First Adult Winter: Not indicative of the bird's age but rather bird's first full set of adult winter feathers, usually reached during the year of hatching although with some birds it may be up to 2 -3 years before the bird moults into this plumage. This plumage is reached after moulting from juvenile plumage (but see remarks under First Winter, usage 2, below). Also known as first non-breeding plumage or first basic plumage

First Winter (there are two usages of this term):

• 1: synonymous with First Adult Winter
  
• 2: the plumage a bird is wearing during its first winter, i.e., the plumage that is reached moulting from juvenile plumage. In passerines, that moult normally is incomplete, so some juvenile feathers are retained (for example primary coverts, tertials and sometimes other feathers). Therefore, it is in principle always possible to distinguish first winter birds from later age classes (especially on shape of feather tips but not necessarily on color, even though the older feathers have a tendency to be duller than the fresh ones).

This page is divided into four sections: Dictionary A-F, Dictionary G-L, Dictionary M-S and Dictionary T-Z.