Abstract
The Carrion Crow Corvus corone has two distinct social types: territorial pairs and flocks of non-territorial individuals. The foraging area and roost utilization of territorial and non-territorial individuals were studied in Ina Basin from 20 March 1992 to 31 December 1993. To study behavior at the individual level, I banded 96 non-territorial birds (1 year old=30, over 2 years old=66) and in addition attached radio transmitters to 10 of them. Territorial individuals defended their territories with their partners. The teeritorial pattern was stable throughout the year. Non-territorial individuals formed flocks and foraged in areas of farmlands and riverbed which were not occupied by territorial pairs, and shifted foraging areas seasonally. Territorial birds could become non-territorial if their territory was taken over by other crows. Radio-tracking studies showed that non-territorial birds changed roost sites during the study period. Most non-territorial individuals were sexually immature. I conclude that young birds of both sexes change foraging areas and roosts to increase the chance of becoming territory owners and live in flocks only until they can acquire a breeding territory.
