Cats, cars, and crossings: The consequences of road networks for the conservation of an endangered felid

• Main Authors: AnnMarie Blackburn, Levi J. Heffelfinger, Amanda M. Veals, Michael E. Tewes, John H. Young, Jr.
• Format: Article
• Language: English
• Published: Elsevier 2021-06-01
• Series: Global Ecology and Conservation
• Subjects: Anthropogenic encroachment; Cox proportional hazards; Demographics; Endangered species; Kaplan-Meier; Ocelot
• Online Access: http://www.sciencedirect.com/science/article/pii/S2351989421001323

Encroaching urban development is a leading cause of habitat loss, replacing natural areas with anthropogenic infrastructure and road networks. Roadways can influence the spatial ecology and survival of mammalian carnivores, particularly felids, thereby threatening long-term persistence and conservation of sensitive populations. Ocelots (Leopardus pardalis) are a federally endangered felid in the United States with breeding populations restricted to the Lower Rio Grande Valley of South Texas, an area of extensive anthropogenic expansion. We evaluated the influence of road networks on ocelot survival using a long-term telemetry dataset (1982–2001, n = 59) and draw comparisons with a spatially referenced historical dataset of ocelot-vehicle collisions in the same area (1982–2020, n = 54). Vehicle collisions accounted for 40% of radio-collared ocelot fatalities. Annual survival rates were 0.90 (95% CI = 0.84–0.95) for resident ocelots and 0.66 (95% CI = 0.45–0.97) for transient ocelots. We evaluated biological and road-related factors that may influence ocelot survival using Cox proportional hazards regression. The top model included density of unpaved, low-volume, and high-volume roads within home ranges and resident-transient status. Mortality risk increased 16% with every 0.07 km/km2 increase of high-volume roads within annual home range, decreased 45% with every 1.12 km/km2 increase of unpaved roads, and decreased 276% for residents compared to transients. Further, probability of mortality specifically from vehicle collision increased with greater density of low-volume roads within ocelot home ranges. Within the historical dataset of ocelot-vehicle collisions, 46% occurred on low-volume roads while 39% occurred on high-volume roads. Our results highlight the necessity for mitigation strategies on low-volume roads which cause the most ocelot-vehicle collisions. In addition, continued attention towards high-volume roads is necessary to ocelot conservation. Understanding how road attributes affect the survival of species sensitive to urbanization and habitat fragmentation can aid in their conservation.