American Ornithologists' Union Annual Meeting, Minneapolis, MN, August 1997.
Routes to breeding in Eastern American Crows. KEVIN J. MCGOWAN, Ecology & Systematics, Cornell Univ., Ithaca, NY.
American Crows, Corvus brachyrhynchos, are long-lived birds with complicated social relationships. In a nine-year study in central New York, young crows marked in the nest were followed during subsequent years to gather information on dispersal, survival, and age at first breeding. Most crows act as helpers before breeding; 80% of observed nests were attended by three or more crows. Helpers usually were offspring of the breeding pair from previous years. Crows may remain as helpers for up to six years, although some individuals wander and never help at home. No crow in the study bred before the age of two, and most became breeders only at the age of four years or older. Females tended to breed at an earlier age than males. Dispersal from the natal territory to a breeding site ranged from 0 to 64 km, with females tending to travel further distances. Strategies to obtain breeding spots include inheriting the home territory on the death of the parents, budding off a piece of the natal territory, replacing a breeder near the natal territory, replacing a breeder at a distance from the natal territory, dispersing with a sibling to act as helper at that territory, and joining an unrelated family group and waiting for the breeder to die.
Kevin J. McGowan
Section of Ecology & Systematics
Corson Hall, Cornell University
Ithaca, NY 14853-2708
McGowan, K J