Skip to main content
Open Access Publications from the University of California


The International Journal of Comparative Psychology is sponsored by the International Society for Comparative Psychology. It is a peer-reviewed open-access digital journal that publishes studies on the evolution and development of behavior in all animal species. It accepts research articles and reviews, letters and audiovisual submissions.

Volume 9, Issue 2, 1996

Research Article

Numerical Competence in Ferrets

Ferrets were tested in a free feeding situation that required them to eat only three pieces of food from a randomly sized larger array containing between 15-20 items. Controls were established to preclude discrimination based on spatial or volumetric cues, or cuing by the experimenter. This demonstration represents the first evidence of numerical competence in a mustelid species, and replicates the results of pioneering research by Koehler and his associates with budgerigars (Marold, 1939), as well as more recent work with rats (Davis & Bradford, 1991). Although the performance of ferrets reached comparable levels to those reported with other species, extended training yielded a deterioration in performance. These results are discussed in terms of the role of consequences to suppress competing responses, a problem that has been reported to underlie a variety of learning situations with ferrets.

Book review - Inidivdual Development and Evolution: The Genesis of Novel Behavior

Individual Development and Evolution: The Genesis of Novel Behavior,by Gilbert Gottlieb, Oxford University Press, N.Y., 1992,231pp.