Food-caching in timber wolves, and the question of rules of action syntax

This report presents data on the sequence of motor operations used by captive timber wolves to cache food. Videotapes were obtained of 151 caching episodes by 8 wolves. The vast majority of these episodes contained 3 distinct phases, each composed of movements unique to that phase. The excavation of the cache site was always done with the forefeet, and burying of the food was always done with the snout. Both the identity of the movements, and the serial order of phases were independent of the sex of the animal, the season in which the observations were made, and the nature of the substrate. A comparison of the temporal sequencing of these actions with the temporal stereotypy seen in rodent motor patterns (e.g. grooming) revealed a striking phenomenological similarity. The factors shaping the temporal sequencing in the two behaviors are, however, probably very different. This is because much, though not all, of the temporal stereotypy in the sequence of movements used by the wolf in caching is constrained by the logistics of the cache operation, while this is not the case for the phases of facial grooming in rodents. The implications of our data for the kinds of behavioral evidence required for ascription of such stereotypy to a central pattern generator are discussed.