Prey Selection in the American Kestrel: Experiments with Two Species of Prey

Abstract

Each of seven American kestrels was offered a single white mouse for 10 consecutive captures each day. On the eleventh trial the birds were offered a choice between a mouse and a young domestic chick. This procedure was repeated daily for 16 days or for 15 days after the first chick was selected. The entire series was then replicated offering 10 chicks, and then a choice. Three birds showed a significant preference for chicks throughout both parts of the experiment; this was interpreted as selection for "easy" prey. Four birds preferred chicks in the first part of the experiments and mice in the second part, indicating a preference for odd prey. I conclude that oddity influences prey selection in multispecies prey systems, but that this influence can be obscured by other factors, such as the difficulty of prey capture.