© 1991 International Society for Behavioral Ecology
research-article |
Utilization of different prey type patches in the Ural owl(Strix uralensis): a sit-and-wait predator
Graduate School of Agricultural Science, University of Tsukuba, Ibaraki 305, Japan
Institute of Biological Sciences, University of Tsukuba, Ibaraki 305, Japan.
ABSTRACT
To quantify the pattern of allocation of foraging activity of a sit-and-wait forager among feeding sites of different profitability, I conducted an experimental study of patch utilization behavior of Ural owls (Strix uralensis) in an experimental flight cage. The owls were allowed to search among four patches containing equal numbers of mice, two with the large Japanese field mouse (Apodemus speciosus) and two with the small Japanese field mouse (A. argenteus). Patches with A. speciosus were more profitable than those with A. argenteus, and owls visited more profitable patches more frequently. Visiting frequency to richer patches did not increase with experience; however, owls changed search time according to experience. Search time in a patch became longer in later visits than in earlier visits during a given night according to an owl’s sampling experience among patches. Furthermore, owls stayed longer in richer patches than in poor ones if they had caught mice in both types of patches. Search time had great variance. Mean search time that ended with attack was longer than that ended without attack (give up). In effect, Ural owls improved their resource utilization pattern as they accumulated experience in the environment. [Behav Ecol 1991;2:99–105J]