Papers in the Biological Sciences


Date of this Version



Published in Ethology 88, 128—144 (1991) Copyright © 1991 Paul Parey Scientific Publishers, Berlin and Hamburg.


Kea are omnivorous parrots endemic to the high mountains of the South Island of New Zealand. Over a two-year period, we recorded quantitative behavioral data from 38 banded male kea foraging at a refuse dump outside Arthur's Pass National Park and analyzed the effects of social factors on the ontogeny of foraging. Members of the four distinguishable age classes — fledglings, juveniles, subadults, and adults — displayed characteristic differences in foraging ability and in the social behavior used to obtain access to resources. Adults performed most of the excavation that uncovered new food resources. Fledglings explored and manipulated objects almost continuously, but they discovered little food on their own and were commonly fed directly by adults. Juveniles obtained the highest foraging yields for the amount of time spent searching of any age class, aided by appeasement behavior that gave them preferential access to foods discovered by adults. Kleptoparasitism served as a primary foraging strategy for subadults, who were otherwise poor at discovering and retaining food resources. Social factors influence the acquisition of foraging expertise in the Kea in different ways at different stages of development.