Date of Graduation

12-2023

Document Type

Thesis

Degree Name

Master of Science in Biology (MS)

Degree Level

Graduate

Department

Biological Sciences

Advisor/Mentor

DeGregorio, Brett A.

Committee Member

Roberts, Caleb P.

Second Committee Member

Mortensen, Jennifer L.

Third Committee Member

Sasse, Blake

Keywords

Gray Fox; Landscape Configuration; Species Distribution Model; Spotted Skunk

Abstract

Much of the landscape of the United States has been altered by humans, leading to the eradication of most populations of large mammalian predators. Consequently, many species of mammalian mesopredators (medium-sized mammalian predators) have come to dominate the landscape. Species such as the gray fox (Urocyon cinereoargenteus) may appear to be on the rise and doing well due to their widespread range, but at a local scale may need monitoring and less is known in areas of its range. Others such as the plains spotted skunk have a wide range across the plains but are on the decline even with the lack of dominant apex predators. Unpacking the trends of these mesopredators in a changing environment can be complicated, but necessary. In my first chapter I look at the plains spotted skunk (Spilogale interrupta) as it is in decline range-wide. We developed a presence-only species distribution model using only occurrence records from Great Plains and adjacent prairie ecoregions. We found most scales of response to be at the 100m scale, except for water cover which occurred at the 6km scale. Water cover was the strongest predictor of spotted skunk occurrence. We found non-linear relationships between spotted skunk presence and anthropomorphic variables such as open space and development where skunks were positively associated with these landcovers at lower levels but would become negatively associated when both landcovers became more prevalent. When we projected our results across the region, our predictive map showed strong predicted habitat suitability in areas with heterogenous landscapes and abundant riparian areas. This may indicate that the plains spotted skunk may be a habitat generalist and distribution may be driven more by fine scale resources such as prey density or shelter rather than landcover alone. For my second chapter, I examined a more common, charismatic, furbearer species: the gray fox (Urocyon cinereoargenteus). To address a gap in our understanding of the gray fox we initiated a large-scale camera trapping effort to understand how this species responds to forest types and forest configuration across multiple spatial scales. Specifically, we sought to explore how the gray fox responds to the configuration of forest patches, and density of forest edge habitat. We found across spatial scales, gray foxes were negatively associated with evergreen forest cover and positively associated with deciduous forest cover. The negative association with evergreen forest is likely due to the type of evergreen forest in this area which is mainly pine plantations. We also found the top models selected at all scales included some form of landscape configuration metric such as edge or patch density. We also note that even though the patterns did not change between scales the configuration metrics may depend on the scale of investigation. When investigated at a small scale, deciduous forest patch density best explained gray fox occupancy whereas at a medium scale, evergreen forest edge and deciduous forest edge density best explained gray fox occupancy and finally at large scales we saw evergreen forest edge density as the best model.

Download

Available for download on Friday, February 06, 2026

Share

COinS