Additional Funding Sources

This research, conducted at the Raptor Research Experiences for Undergraduates site, was supported by the National Science Foundation and Department of Defense under Grant No. DBI-1852133 and by Boise State University.

Abstract

The Morley Nelson Snake River Birds of Prey National Conservation Area (NCA) of southern Idaho is an important area for raptors and scavengers. Recreational shooting is popular in the NCA, and intensity of shooting varies throughout the area. Recreational shooting includes target shooting of inanimate objects as well as shooting of unprotected mammals, especially Piute ground squirrels (Urocitellus mollis). Ground squirrel carcasses are typically left on the landscape, where they are then scavenged by many raptor species, as well as other avian and mammalian scavengers. Differences in raptor and scavenger abundance may impact nesting success of prey species including the Long-billed Curlew (Numenius americanus), a species of conservation concern, as well as the abundant but declining Horned Lark (Eremophila alpestris). We investigated the relationship between recreational shooting and the abundance of raptors and Common Ravens (Corvus corax), predicting that these species would be attracted to the carcasses left by ground squirrel shooting, and therefore be more abundant in areas where recreational shooting occurs. From May to July 2021, we conducted eight replicates of walking surveys on ten 1 km2 grids within the NCA that experience varying recreation intensity. Preliminary analyses with approximately half of the season’s data suggest a significant difference in raptor abundance between high and low recreation grids, with higher abundance at high recreation grids. Final analysis will be done with an even sample size at each grid, and we will use a ranking system for recreational shooting intensity instead of the binary high versus low recreation classifications. We will also examine other characteristics of each grid, including ground squirrel abundance, habitat type, and proximity to roads, power lines, and human development, to explore the relative importance of recreational activity in shaping the distribution of raptors and scavengers.

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Impacts of Recreation on Raptor and Scavenger Abundance in the Morley Nelson Snake River Birds of Prey National Conservation Area of Southern Idaho

The Morley Nelson Snake River Birds of Prey National Conservation Area (NCA) of southern Idaho is an important area for raptors and scavengers. Recreational shooting is popular in the NCA, and intensity of shooting varies throughout the area. Recreational shooting includes target shooting of inanimate objects as well as shooting of unprotected mammals, especially Piute ground squirrels (Urocitellus mollis). Ground squirrel carcasses are typically left on the landscape, where they are then scavenged by many raptor species, as well as other avian and mammalian scavengers. Differences in raptor and scavenger abundance may impact nesting success of prey species including the Long-billed Curlew (Numenius americanus), a species of conservation concern, as well as the abundant but declining Horned Lark (Eremophila alpestris). We investigated the relationship between recreational shooting and the abundance of raptors and Common Ravens (Corvus corax), predicting that these species would be attracted to the carcasses left by ground squirrel shooting, and therefore be more abundant in areas where recreational shooting occurs. From May to July 2021, we conducted eight replicates of walking surveys on ten 1 km2 grids within the NCA that experience varying recreation intensity. Preliminary analyses with approximately half of the season’s data suggest a significant difference in raptor abundance between high and low recreation grids, with higher abundance at high recreation grids. Final analysis will be done with an even sample size at each grid, and we will use a ranking system for recreational shooting intensity instead of the binary high versus low recreation classifications. We will also examine other characteristics of each grid, including ground squirrel abundance, habitat type, and proximity to roads, power lines, and human development, to explore the relative importance of recreational activity in shaping the distribution of raptors and scavengers.

 

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