Conditioned Responses in Crows

Abstract

The following experiments were designed to determine the role of traditions in the well-known mobbing behavior of the Common Crow, Corvus brachyrhynchos, toward owls. The extensive literature on enemy recognition in birds has been reviewed by Nice (1943) and need not be reviewed here. It is sufficient to note that since the experiments of Thorndyke (1899) somes tudents have held to the position that the inherent fear responses of birds are generalized. Others, such as Lashley (1938), have taken the position that just as birds have an innate perceptory pattern of the nest characteristic of the species so they may also have an inherent pattern of certain enemies. Lorenz (1935) found that his Jackdaws, Corvus monedula, had to learn what to fear from their parents or from other members of the social group. Nice and ter Pelkwyk (1941) reported that Song Sparrows, Melospiza melodia, showed moderate alarm at all the mounted birds used, including Hornbills, Bucerotidae, and Grouse, Bonasa umbellus, and strong alarm at the Barred Owl, Strix varia. They also found that Song Sparrows had to learn to recognize cats and Cowbirds, Molothrus ater, as enemies. Rand (1941) found that his hand-reared Thrashers, Toxostomac urvirostre, regarded owls as objects of curiosity until they moved. From such extensive experiments Rand (1942) was led to suggest that mobbing behavior represents a conflict between two opposing tendencies: the tendency to flee (fear) and the tendency to approach (curiosity). Lack (1941) made essentially the same suggestion with the exception that he emphasized the tendency to attack as one of the conflicting impulses.