Date of Award
8-2025
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Forestry and Environmental Conservation
Committee Chair/Advisor
David S. Jachowski
Committee Member
Erin K. Buchholtz
Committee Member
Michael J. Childress
Abstract
Road networks are a major driver of habitat fragmentation and wildlife mortality. Wildlife crossing structures (WCS) are a common mitigation strategy with the goal of maintaining landscape connectivity, reducing wildlife-vehicle collisions, and facilitating safe passage across highways. Most research on WCS prioritize large ungulates or carnivores, leaving potential gaps in our understanding of how diverse mammalian communities interact with these features. We investigated spatial, temporal, and behavioral patterns of small-, medium-, and large-bodied mammals using WCS in the southern Blue Ridge Mountains of North Carolina and Tennessee. Using remote camera data from structures on I-40 and I-26 collected from 2018 to 2023, we assessed visitation and successful crossings across a range of carnivore species. We then monitored a subset of WCS (including US-276) from 2024 to early 2025 and examined how fear-based behaviors (e.g., flight, pausing) varied with traffic, structure features, and natural disturbance events, like Hurricane Helene. We first evaluated interspecific interactions and modeled visitation intensity using N-mixture models for focal carnivore species (black bear, bobcat, coyote, red fox). We then modeled successful crossing events using generalized linear mixed models (GLMMs) and included river otter, American mink, and long-tailed weasel. We conducted behavioral analyses using video footage categorized into fear-based (pausing, fleeing) and neutral (foraging, non-reluctance) behaviors for black bear, white-tailed deer, raccoon, and coyote with univariate linear models and beta GLMMs. We observed no strong evidence of spatial or temporal avoidance between carnivores at crossing structures, though carnivores used different structures from large ungulates. Visitation and crossing patterns, however, were strongly species-specific: black bears visited WCS near forest cover, bobcats were associated with prey activity, and red foxes selected WCS farther from water. Successful crossings were more likely when animals traveled in groups and were less likely in structures inundated with water and with higher human activity. Fear-based behaviors were associated with traffic for bears and deer consistent with the Risk Disturbance Hypothesis. Raccoons and deer showed fewer fear-based responses at both the highest- and lowest-trafficked roads, consistent with the Predation Risk Allocation Hypothesis. Coyotes did not exhibit significant behavioral shifts, reflecting their unique adaptability and behavioral plasticity. Following Hurricane Helene, when roadways were temporarily closed, we observed increases in fear-based behaviors among deer and raccoons indicating that extreme climate events can also shift behavior. Collectively, these findings highlight the complex and context-dependent nature of wildlife behavior on roadsides. Structural design, landscape features, social behaviors, and external stimuli all influence species’ use of structures. Broadening WCS evaluation beyond large target species and incorporating behavior can improve the effectiveness of highway mitigation strategies, making roads safer for both people and wildlife.
Recommended Citation
Horton, Chloe E., "Mammal Use of Crossing Structures on Highways In the Southern Blue Ridge Mountains" (2025). All Theses. 4590.
https://open.clemson.edu/all_theses/4590