2024 Undergraduate Research Showcase

Prairie Falcon Predation Continues on Dwindling Prey Populations

Document Type

Student Presentation

Presentation Date

4-19-2024

Faculty Sponsor

Dr. Jen Cruz

Abstract

Human influences can have dire consequences on ecosystems both directly and indirectly. Hotter conditions due to climate change, increased fire frequency, intensive grazing, and invasive plant species have reshaped the sagebrush ecosystem of southwest Idaho, impacting small mammals. Small mammals provide many ecosystem services while being a crucial prey item for raptors. One such species: the Piute ground squirrel (Urocitellus mollis) historically reached population highs of 52.5 individuals per hectare; however, recent surveys suggest these populations reduced to 1.7-3.8 per hectare. We sought to find how this change impacted Prairie Falcon (Falco mexicanus) diets. We placed nest cameras at four Prairie Falcon nests in southwest Idaho during 2023 to quantify prey deliveries and compared them against diet studies from the early 1990s. We found that ground squirrels made up 33 to 79% of prey deliveries, which matched findings during times of far greater squirrel abundance. These results support prior research classifying Prairie Falcons as specialist predators, but coupled with low ground squirrel numbers, imply there is a more drastic reliance on them as a food source. Ongoing declines of ground squirrel populations may result in a delayed density response for Prairie Falcons--potentially slashing their abundance.

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