Sex-related Differences in Habitat Use in Wintering American Kestrels

Abstract

AbstractWe investigated sex-related differences in habitat use in wintering American Kestrels (Falco sparverius) at two scales: within a 10 m radius and within a 100 m radius of perch sites. Female kestrels used areas containing a higher percentage of short vegetation (<0.25 m high) suitable for foraging than did males at both scales (100 m radius females 80%, males 69%; 10 m radius females 80%, males 73%). At both scales, females had more pasture (a high-quality foraging substrate) available than did males; areas within a 100 m radius of male perch sites contained more woodlot than did female perch sites. Logistic regression models indicated greater overlap between male and female habitat use on a 10 m radius scale than on a 100 m radius scale, suggesting that males may preferentially select smaller areas devoid of woody vegetation relative to what is available within 100 m radius of perch sites. Our results suggest that males may be constrained to winter in areas with lower overall foraging opportunities and possibly higher predation risk than areas used by females. Our work supports the hypothesis that males and female kestrels prefer open areas as wintering habitat.