GLOSSARY OF TECHNICAL TERMS 
69 
GLOSSARY OF TECHNICAL TERMS NOT ON TOPOGRAPHY 
OF A BIRD 1 
[After Ridgway’s Nomenclature of Colors, First Edition, pp. 61-1 IS, 1886.] 
Adult: A bird which has reached fully mature or final plumage. 
Asymmetry: Lack of symmetry on opposite sides, as in the skulls of some owls. 
Axillaries: A more or less distinct tuft of feathers, usually soft and elongated, 
growing from the armpit or axilla. 
Bars: Lines across the body (see Stripes). 
Bend of the Wing: The front projection of the folded wing. 
Cere: The naked skin, membrane, or wax-like swelling, in which the nostrils are 
situated, as in birds of prey and pigeons. 
Crepuscular: Birds which become active during twilight, as nighthawks and whip- 
poor-wills. 
Crest: A more or less lengthened, erectile, or permanently erect tuft of feathers on 
top of the head. 
Crissum: The feathers between the lower tail coverts and the anal region. 
Dichromatism: Two color forms of one bird, as the rufous and gray screech owls, 
or white, blue, or dusky forms of some herons. 
Disc \ 
Disk | : ^ se ^ ra di a ting feathers surrounding the eye, as in the owls. 
Dorsal: Pertaining to the back. 
Down: Small, soft, decomposed feathers which clothe the nestlings of many birds, 
and which also grow between and underneath the true feathers in many adults, 
especially waterfowl. 
Ear-tufts: Erectile tufts of elongated feathers on each side of the crown, suggesting 
the external ears of many mammals; especially characteristic of the owls. 
Edge of the Wing: The anterior border of the wing. 
Ferruginous: Rust-red. 
Gape: The opening of the mouth. 
Gorget: An ornamental throat patch, distinguished by color or texture, as the gorget 
of a hummingbird. 
Hooded: Having the head conspicuously different in color from the rest of the plu¬ 
mage; as in some gulls. 
Immaculate: Without spots or markings. 
Immature: Not adult. 
Insectivorous: Feeding upon insects. 
Interscapulars: The feathers between the scapulars—on the back. 
Iridescent: With changeable colors which vary according to the light. 
Iris: The colored circle surrounding the black center or pupil of the eye. 
Juvenal: In plumage, that following the nestling down. 
Topography of a Bird, p. 72. 
