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Long-term prairie falcon population changes in relation to prey abundance, weather, land uses, and habitat conditions

The Condor

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Abstract

We studied a nesting population of Prairie Falcons( Falco mexicanus) in the Snake River Birds of Prey National Conservation Area (NCA) from 1974-1997 to identify factors that influence abundance and reproduction. Our sampling period included two major droughts and associated crashes in Townsenda??s ground squirrel (Spermophilus townsendii) populations. The number of Prairie Falcon pairs found on long-term survey segments declined significantly from 1976-1997. Early declines were most severe at the eastern end of the NCA, where fires and agriculture have changed native shrubsteppe habitat. More recent declines occurred in the portion of canyon near the Orchard Training Area (OTA), where the Idaho Army National Guard conducts artillery firing and tank maneuvers. Overall Prairie Falcon reproductive rates were tied closely to annual indexes of ground squirrel abundance, but precipitation before and during the breeding season was related inversely to some measures of reproduction. Most reproductive parameters showed no significant trends over time, but during the 199Os, nesting success and productivity were lower in the stretch of canyon near the OTA than in adjacent areas. Extensive shrub loss, by itself, did not explain the pattern of declines in abundance and reproduction that we observed. Recent military training activities likely have interacted with fire and livestock grazing to create less than favorable foraging opportunities for Prairie Falcons in a large part of the NCA. To maintain Prairie Falcon populations in the NCA, managers should suppress wildfires, restore native plant communities, and regulate potentially incompatible land uses.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Long-term prairie falcon population changes in relation to prey abundance, weather, land uses, and habitat conditions
Series title:
The Condor
Volume
101
Issue:
1
Year Published:
1999
Language:
English
Contributing office(s):
Forest and Rangeland Ecosystem Science Center
Description:
p. 28-41
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
The Condor
First page:
28
Last page:
41
Number of Pages:
14