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Nest-site characteristics and linear abundance of cliff-nesting American kestrels on San Clemente Island, California

Journal of Raptor Research

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Abstract

American Kestrels( Falco sparverius) are typically secondary-cavity nesters, and use of natural cliff cavities for nest sites is less-commonly reported. On San Clemente Island (SCI), California, however, American Kestrels nest primarily on cliffs in major canyons(93%), to a lesser extent on seacliffs(4%), as well as in man-made structures (3%). We located and mapped 99 American Kestrel territories on SCI, and recorded 11 nest-site characteristics at 40 cliff nests during 2001-02. Nest cliffs were typically fractured igneous rock with mean height of 16.1 m +_ 1.8 SE. Mean slope of nest cliffs was vertical (x=91 degrees). Nest cliffs and cavities were significantly oriented to the southeast, away from the prevailing wind direction(NW). In eight canyons, where we believe that we found all occupied American Kestrel territories, the mean linear abundance was 2.1 pairs/km, greater than most published estimates. Contrary to most previous studies, no American Kestrels nested in tree cavities despite their presence in SCI canyons. The absence of cavity-excavating breeding birds from the island likely restricts kestrels to nesting in naturally-formed cavities and man-made structures.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Nest-site characteristics and linear abundance of cliff-nesting American kestrels on San Clemente Island, California
Series title:
Journal of Raptor Research
Volume
37
Issue:
4
Year Published:
2003
Language:
English
Contributing office(s):
Forest and Rangeland Ecosystem Science Center
Description:
p. 323-329
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Raptor Research
First page:
323
Last page:
329
Number of Pages:
7