Predatory Efficiency of American Kestrels Wintering in Northwestern California
Journal
Raptor Research
Volume
7
Issue
2 (Summer)
Year
1973
Pages
25-31
Section
Scientific Papers
Online Text
Abstract
A study of foraging behavior of the American Kestrel (Falco sparperius) wintering in Humboldt County, California was undertaken from October 1972 to February 1973. An analysis of predatory efficiency and prey selection is presented on the basis of numbers of species taken relative to the number of capture attempts, and the relative frequency with which they occur in the Kestrel's diet. A total of 498 capture attempts was observed; of these, 233 (46.8%) were successful, 221 (44.4%) were unsuccessful, and 44 (8.8%) were undetermined. Of the 233 successful captures 199 (85.4%) were invertebrates (beetles, grasshoppers, earthworms, butterflies and other insects) and 34 (14.6%) were vertebrates (mice, shrews and birds).
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