Early Ontogeny of the Behavior of Young in Large-Billed Crows (Corvus macrorhynchos) in Their Natural Habitat

Abstract

The early ontogeny of behavior of corvid juveniles in their natural habitat was studied, and the large-billed crow (Corvus macrorhynchos) taken as an example. Research was carried out from May to October, 2012, in a wildlife area (Malye Kurily Reserve, part of the Kuril’skii State Nature Biosphere Reserve, Shikotan Island) on a free-living population of these birds. Twenty-five individually marked chicks from ten broods were observed from the moment of their hatching (early June) to the beginning of September (the time when fledglings became independent). The results obtained allowed us to follow not only the development of individual forms of behavior in chicks, but also the process of their incorporation into the population’s social structure. The development of the behavioral repertoire in large-billed crows in their natural habitat was shown to be identical to that of hooded crows. But in contrast to hooded crows, large-billed crows continue looking after their young even after the latter leave their nest territory. This may expand the capacities of social learning and skill transfer. Unlike the large-billed crow adults of the Shikotan population, in which aggression to their kin is very high, the young show no aggression to other juveniles. Moreover, we observed the formation of positive contacts between fledglings from different families during their play. This feature of fledgling behavior probably plays an important role in the incorporation of the young into the social structure of the population.