Summer Habitat Used by American Kestrels in Santa Clara County, California

Abstract

Urbanization can be a primary source of the loss of native species populations by causing habitat loss, fragmentation and land conversion (Tilman et al., 2001; Krauss et al., 2010; Marzluff, 2001). Birds of prey, which are mid or top carnivores, are especially at risk from the loss of habitat that can occur on both the breeding and wintering grounds. Raptors can be considered environmental indicators of habitat degradation because of their small populations, low population densities, and high position in local food webs. This research investigated the habitat preference of the American Kestrel (Falco sparverius) (kestrel), a widely distributed raptor, whose populations have been declining in the U.S. and may be declining in Santa Clara County in northern California. The land cover and habitat features with which kestrels associated were identified by collecting in situ records of habitat features and conducting point counts of kestrels. Results showed an association between kestrel presence with grassland/shrub/scrub and pasture/hay/crops land cover, especially in open space conditions, indicating that conservation of these habitats could help protect American kestrel populations. Installing more kestrel nest boxes in grassland/shrub/scrub and pasture/hay/crops conditions with strategic monitoring of reproductive success may benefit populations in this region.