The Columbia, Missouri chapter of the Audubon Society — serving Audrain, Boone, Cooper, Howard, Monroe & Randolph Counties

Definitions for the January 2013 Tips for Tyros

Irruption: In irregular migration (most migrations are regular), in North American, often a spectacular mass movement of birds that normally live year-round in parts of Alaska and Canada. Recent examples... Red Crossbills, Pine Siskins, Snowy Owl

Invasion: The periodic southward influx into the U.S. from Canada and Alaska of birds that usually live year-round in the North. Some authorities, however, prefer the term irruption, and use the term invasion for movement of a bird species into new territory in rapid expansion of its range.

Radiation: In the context of bird distribution, used to describe the movement over time of species, families, etc., out from the regions in which they originally evolved: or in the shorter-term range expansion such as Northern Cardinal, north of breeding limits defined previously. (from The Birdwatchers Companion by Christopher Leahy)

Brood Patch: also incubation patch This is a featherless area of bare skin on the underpart, or belly area, of a bird's body which during the breeding season is thickened and develops a rich supply of blood vessels just under the skin. By pressing this bare, warm area—the incubation patch—against the eggs, the bird helps transfer heat to them from its body.

Distraction: as distraction display—Term of behaviorists for a special display by birds in which they often appear to be sick or crippled and cannot fly strongly—"the broken wing trick." Its function directs the attention of a predator away from the nest or young and toward the adult bird. It is usually most elaborate in birds that nest in the open on the ground.

Ethology: Term used in human sociology for the study of manners, customs, and mores, their growth, decay, and effectiveness, and now used also for the study of animal behavior. The study of functions, biological significance, causation, and evolution of species-typical behavior. Ethologists study almost any kind of undomesticated animal...

Cryptic: That which conceals or is adapted to conceal...see colors of feathers. Many kinds of birds are cryptically marked in that some match so well the ground, shrubbery, or trees in which they live that, when motionless they are difficult or impossible to see; this is called protective coloration. example Northern Bobwhite.

Accidental: or accidental visitor Term for a bird seen in area far outside its normal and/or seasonal range. Birds may ride with storms and strong winds that carry them to regions strange to them or may be transported by alighting on ships. Peterson describes accidentals as "the rarest of rarities—birds that should not occur in your region at all."

Split/Lump: The terms used when scientists/ornithologists determine that a subspecies of bird is actually a separate distinct species and thus split the birds into separate species. The opposite occurs when it is determined that two species are actually not different but are the same and are lumped into a single species (Blue Goose now known to be a different color phase of the Snow Goose and not a different species.)

Brood Parasitism: Birds themselves may have parasitic roles in relation to other species of birds. One of these is called brood parasitism in which females of some species lay their eggs in the nests of other species of birds which then hatch the eggs and raise the young as though they were their own. example Brown-headed Cowbird...known as an obligate parasite because it does not raise its own progeny and is completely dependent on other species of birds to do so.

Diving Duck: Diving ducks often dive deeply for their food. Diving ducks feed underwater aided in their swimming by large feet and short legs which are farther to rear of their bodies than in dabbling ducks; that is why diving ducks are awkward on land and seldom visit crop fields.

Bay Ducks: They are diver ducks that have smaller wings relative to their body weight, resulting in a longer take-off from the surface of the water. To take flight, bay ducks run atop the water, patting their feet on the surface, as they gain speed and lift until they are airborne. (from Enjoying Missouri Birds by Brad Jacobs)

Juvenal: Term applied in ornithology to the plumage of a young bird that comes in immediately after, or succeeding, its natal down. In birds which have no natal down, the term also applies to the first plumage which succeeds the naked nestling stage characteristic of some species. The juvenal plumage is the first in the life of a bird that is composed of true contour feathers.

Juvenile: A juvenile is a young bird that is out of the nest and able to care for itself but has not completed its post juvenal molt.

Something extra to consider: An immature is, in general, a young bird during its first year of life, before it has acquired its adult plumage. However, some birds, such as gulls, may require several years to acquire their adult plumage; during this time, in their various immature plumages, they are called subadults.

Piracy: Refers to the stealing of food from one bird to another, more technically known as kleptoparasitism. The practice has been recorded in many species, including a variety of songbirds. Some raptors and seabirds obtain a significant proportion of their diet by harassing other birds food they have caught, but all avian pirates are fully capable of catching or finding their own food. (from The Birdwatchers Companion, by Christopher Leahy)

The above definitions are quoted from The Audubon Society ENCYCLOPEDIA OF NORTH AMERICAN BIRDS, by John K. Terres, 1996 edition. Exceptions are definitions for Split/Lump, or as noted.

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