Choice of Opponents during Competition for Food among American Goldfinches


Department of Biological Sciences, University of Wisconsin-Milwaukee, P.O. Box 413, Milwaukee, Wisconsin 53201, U.S.A.


Captive American goldfinches (Carduelis tristis) were observed competing over access to a feeder. The goldfinches did not approach the feeder at random. Individuals could determine the rank of a bird on the feeder relative to their own rank and could also distinguish between the ranks of two birds on the feeder. This ability allowed individuals to approach perches occupied by subordinate birds and avoid dominant ones. Individuals could, therefore, avoid aggressive encounters with dominant birds and gain access to the feeder with the least risk. The ability to determine the rank of a potential opponent was probably facilitated by individual recognition.