Wintering Raptors of the Great Basin

Principal Investigator(s):

Alan Hinde, HawkWatch International, Inc.


Salt Lake City, UT

Project Term:

2008 - 2009

Since 1985, Principal Investigator (PI) Al Hinde has conducted a roadside census and banding study of wintering raptors in the Great Basin. Initially, this project was limited to northeastern Nevada and was intended to augment knowledge of regional raptor ecology derived from HawkWatch International’s (HWI) long-term migration study in the Goshute Mountains of northeastern Nevada (on-going annually since 1983; Hoffman and Smith 2003, Smith et al. 2008, Smith and Neal 2009a). By 1989, further exploration throughout Utah and Nevada had revealed eight major concentration areas for wintering raptors, with each roughly 50-mi2 area consistently containing 100–200+ individuals of 18 species (13 diurnal species and 5 owl species). One such area, Lovelock, Nevada, contained a previously undocumented communal roost of 200+ buteos (Rough-legged Hawks [Buteo lagopus], Red-tailed Hawks [B. jamaicensis], and Ferruginous Hawks [B. regalis]) and several Great Horned Owls (Bubo virginianus). Continuing each January, with field assistance from experienced HWI raptor biologists, other ornithologists, and local and state wildlife officials, Mr. Hinde focused on these eight areas, including the Lovelock roost. All sites have continued to sustain similar large numbers of wintering raptors each year. The Lovelock roost routinely contained dozens of mixed-species buteos until this past year. This long-term study suggests that these areas are among the most significant winter ranges for raptors in western North America, and the censuses provide a means of monitoring population changes in relation to habitat, land-use, and climatic changes in the study regions.

The capture and banding of 384 raptors (12 species) over the course of the study—including 112 Rough-legged Hawks, the focal species—also has yielded morphometric, genetic, and photographic data used in several other studies and publications. Following the 2006/2007 season, the project contributed feather and saliva samples to two studies, one examining endocrine disruptors and the other comparing Harlan’s Hawks (B. jamaicensis harlani) with other subspecies of Red-tailed Hawks. In addition, following the past two winter field seasons, the project contributed feather samples to another study examining toxins, pollutants, and heavy metals in raptors. Each of three buteos analyzed thus far showed mercury concentrations below the level above which adverse effects are predicted; however, one Harlan’s Hawk showed a much higher concentration than the others.

This report summarizes the results of winter 2008/2009 roadside census and banding activities conducted in nine primary, known concentration areas in Utah and Nevada, with supplementary information derived from several other areas in the two states.

Project Report: Wintering Raptors of the Great Basin

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