A Comparison of Cawing in the European Carrion Crow (Corvus Corone) and the American Common Crow (Corvus Brachyrhynchos)

Abstract

AbstractThe American common crow (Corvus brachyrhynchos) has a complex communication system in which the meaning of its sound units ("caws") is determined in part by the temporal format in which they are uttered. Among the subsystems of the crow's communication is "ordinary" or "structured" cawing, in which the caws are uttered in sequences of similar caws, organized in discrete bursts. A comparable cawing format appears to exist in the European carrion crow (Corvus corone). 49 sequences of structured carrion crow cawing were recorded in Somerset, England, during the period from September 1976 to June, 1977. These are similar in organization to 20 sequences of American crow cawing which were re-analyzed for comparison, but the carrion crowbursts are significantly longer in the duration of their caws and in the duration of the pauses between caws within a burst and have significantly fewer caws in an average burst. Carrion crow structured cawing displays the same contextual ambiguities as have been reported for structured cawing in the American crow. Some evidence is developed which suggests that in carrion crow structured cawing as in American crow structured cawing, the variations in caw pattern are related to individuality, although the relationship is not a simple one. The distinction between structured cawing and unstructured cawing seems to be related in a loose way to the more general distinction made with oscine vocalizations between songs and calls. The situation is complicated by the fact that in corvids the term song is traditionally applied to a third class of vocalizations with properties quite distinct from structured and unstructured cawing.