American Kestrel Breeding Habitat: The Importance of Patch Size

Document Type

Article

Publication Date

12-1-2009

Abstract

Previous studies have examined vegetative cover and land use immediately surrounding American Kestrel (Falco sparverius) nest sites. However, the relationship of landscape-level habitat structure to nest-site selection has received little attention. Between 1995 and 2007, we erected nest boxes in pastures and meadows in northwestern New Jersey. The number of breeding pairs in boxes ranged from 2 in 1995 to 59 in 2002. We used a Geographic Information System to model habitats used by kestrels (open areas dominated by herbaceous vegetation) and delineated patches of contiguous suitable habitat within the study area and statewide. Nest boxes available in large (>1000 ha) patches of suitable habitat were occupied by kestrels at rates significantly higher than those in medium (250-1000 ha) or small (<250 ha) patches. Large patches exhibited relatively high occupancy rates every year, medium patches were most likely to be occupied during years when kestrels were abundant in the study area, and small patches were used infrequently, regardless of how many breeding pairs were present in the study area. That kestrels disproportionately select nest sites in contiguous patches sufficiently large to include many breeding territories has important implications for conservation strategies. We currently are using information on patch size to implement a statewide nest-box program for kestrels in New Jersey.

DOI

10.3356/JRR-08-67.1

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