Date of Award

Spring 2012

Project Type

Dissertation

Program or Major

Psychology

Degree Name

Doctor of Philosophy

First Advisor

Brett M Gibson

Abstract

A great deal of research suggests that the cognitive abilities of birds in the family Corvidae (crows and jays) are comparable in many aspects to that of apes. Scientists have posited competing hypotheses to explain how complex cognitive abilities arise in a species or group of animals. One such hypothesis, the social-intelligence hypothesis, states that the demands of living in a large, dynamic group drive an animal's need for complex cognitive skills. The ecological-intelligence hypothesis, predicts that generalist foragers develop more highly flexible behaviors and a wider cognitive repertoire than specialist foragers. To date, cognitive research on corvids has focused on corvids that are highly social and are generalist foragers. From a comparative standpoint, I examined the cognitive abilities of a corvid that is relatively asocial and a specialist forager. The Clarks' nutcracker (Nucifraga columbiana) is thought to be perhaps the least social corvid, and it largely specializes on the seeds of one species of pine (Pinus edulis). I tested nutcrackers using several tasks in three broad areas of cognition: inferential reasoning, numerical discrimination, and social intelligence. These experiments represent novel tests of cognitive abilities in this species. I found that the nutcrackers performed in a similar manner as social mammals and corvid birds, in all three areas of cognition. This suggests that social group size may not have a large impact on the development of a broad range of problem solving skills. Rather, ecological pressures associated with finding, extracting, caching and protecting seeds from pilferage may have influenced the development of complex cognition in this species.

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