Bird Vocabulary
| ALTRICIAL | Birds which hatch helpless, unfeathered, and with eyes closed. |
| BARBULE | The part of the feather that branches off from the barb (which, in turn, is a branch from the main rachis) |
| CAMOUFLAGE | Protective coloration (often combined with posture and behavior) which helps make a bird difficult to detect in its environment |
| CLUTCH | The complete number of eggs laid by a single female and incubated together |
| CONE CELLS | Visual cells on the retina associated with color vision and visual acuity at high light levels |
| DRAG | The resistance caused by the body's forward motion in flight |
| ENDANGERED | Species (or other taxonomic units) whose population sizes have fallen to critically low levels and are therefore in immediate danger of extinction without human intervention |
| EXTINCT | A taxonomic unit (such as a species) in which no living individuals remain -- they are gone forever; the concept of extinction may also be applied t populations within species. |
| FOLLICLE | A specialized group of cells in the epidermis (skin) from which feathers grow |
| GENUS | A grouping of closely related species within a family; the genus name is the first part of a species' two-part scientific name. |
| GIZZARD | The muscular portion of the stomach which grinds up food |
| INCUBATION | The care of the clutch of eggs by an adult, usually involving the transfer of body heat to the eggs through the brood patch |
| LEK | A communal display area within which many males gather to attract mates |
| LIFT | The net upward force (counter to gravity) experienced during bird flight, created by the shape of the wing |
| MONOGAMOUS | A mating system involving a simple pair bond formed between one male and one female |
| ORDER | A major taxonomic grouping within a Class (such as Class Aves, or birds) uniting related families. Birds are divided into some 27 to 30 orders (the exact number depends on the viewpoint of the scientist) |
| OVARY | The female reproductive organ within which the reproductive cells (eggs) are formed; most birds have only a single developed ovary |
| POLYGAMOUS | A mating system in which a bird of one sex may have two or more mates of the opposite sex |
| PRECOCIAL | Birds which hatch in advanced state of development, with a covering of feathers, open eyes, and the ability to be active. |
| RACHIS | The central shaft of the contour (body and flight) feathers, from which the barbs originate |
| ROD CELLS | Visual cells on the retina that are sensitive in low light situations and are typical of birds that are active at night |
| SPECIES | A "kind" of bird, usually referring to a group of interbreeding natural populations which are reproductively isolated from other such groups; a species represents a unique evolutionary lineage |
| TESTES | The male reproductive organs within which the reproductive cells (sperm) are formed; birds possess paired testes |
| THERMALS | Rising currents of warm air (usually forming over ground rather than water); soaring birds make use of thermals for lift |
| UROPYGIAL GLAND | The "preen gland" which secretes an oil used for feather hygiene and waterproofing |
| VANE | The surface area of a contour feather, formed by all the collective side branches off the rachis (central shaft) |