Joint meeting of the American Ornithologists' Union, the Cooper Ornithological Society, and the Wilson Ornithological Society, Missoula, MT, June 1994.
Cities: opportunities or traps for the American Crow? Kevin J. McGowan, Section of Ecology & Systematics, Cornell University, Ithaca, NY 14853.
American Crows (Corvus brachyrhynchos) have become common urban birds, both roosting and breeding in cities and towns. Their presence in urban areas is a relatively recent phenomenon, having become common perhaps only in the last 30 years. With an increase in gun laws and a changing public attitude toward crows, urban areas could be newly available breeding opportunities. Fewer nest predators and dependable food supplies could even make cities preferred nesting localities. Another possibility exists, however, that cities could be ecological traps: attractive nesting areas that do not allow breeders to replace themselves in the population. This study examined nesting biology of urban and rural crows around Ithaca, New York. Comparisons were made of timing of nesting, nest density, helper presence, nest success, chick growth, and fledgling survival. Urban American Crows nested significantly earlier and at higher densities than rural crows. Nest success was equal between the areas, but rural nests produced significantly larger young. Crows produced in town had high survival and some eventually were able to gain breeding opportunities. Urban nesting appears to be an opportunity, not a trap.