Wintering Raptor Philopatry Study October 2001 - March 2002

Publication Type:

Unpublished

Authors:

Mattox, W. G.; McKinley, J. O.

Source:

Conservation Research Foundation, Boise, p.5 p. + tables (2002)

Call Number:

U02MAT01IDUS

Keywords:

aves, buteos, southwestern Idaho, species of concern, winter raptor surveys

Abstract:

This report presents the fourth season results of a study gathering field data on the occurrence of winter philopatry of individual raptors, based on capture-recapture and identification through the reading of color alpha-numeric tarsal bands. The study site included the Orchard Training area (OTA) and Marsing-Homedale area (H/T) in southwestern Idaho. From the end of October 2001 to early March 2002, 2,819 individuals of 15 species (including 25 unidentified Buteos) were documented during road surveys. The most abundant species observed was the Red-tailed Hawk (971), followed by the American Kestrel (845), Northern Harrier (617), and Rough-legged Hawk (252). These four species made up 90 per cent of all raptors noted. Because of the potential for duplication of species observations, the totals reflect the relative occurrence of species within the study area. In addition to the raptors observed, 15 individual raptors were captured and banded. Further study is recommended due to the variable nature of some raptor species’ abundance and the constant abundance of others. The Prairie Falcons and Red-tail Hawks are of particular concern, which showed evidence of possible poisoning.