If you build it, will they come? A comparative landscape analysis of ocelot roadkill locations and crossing structures

Abstract

Wildlife-vehicle collisions can have a substantial influence on the mortality rates of many wildlife populations. Crossing structures are designed to mitigate the impact of road mortality by allowing safe passage of wildlife above or below roads, and connect to suitable areas on both sides of the road. Ocelots (Leopardus pardalis) are a federally endangered felid in the United States, with remnant populations of <80 individuals remaining in the Lower Rio Grande Valley of South Texas. Vehicle collisions are the greatest known source of mortality for ocelots in Texas. Crossing structures designed for ocelot use have been implemented throughout South Texas since the 1990s, however, ocelots rarely use them. We compared landscape characteristics between ocelot crossing structures and ocelot-vehicle collision sites. We quantified the spatial distribution of woody and herbaceous cover types surrounding ocelot crossing structures (n = 56) and ocelot-vehicle collision sites (n = 26) at multiple spatial extents and compared landscape metrics between these location types. The landscape surrounding ocelot crossing structures had 17–22% more open herbaceous cover >1,050 m from the road, and 1.2–5.8 ha larger herbaceous patches >450 m from the road compared to ocelot-vehicle collision sites. Additionally, many crossing structures installed during the 1990’s are situated >100 km away from an extant ocelot population. Results from this study can guide conservation planners to place future road crossing structures in areas more likely to be used by ocelots. Our results also emphasize that reliable scientific data must be used for effective mitigation efforts. In the absence of data, post-installation assessments can improve the placement of future structures.

Multiscale habitat relationships of a habitat specialist over time: The case of ocelots in Texas from 1982 to 2017

“…Roads influenced home range placement, with ocelots demonstrating a consistent temporal trend to use and select for areas farther from medium‐ and high‐traffic roads. However, ocelots used and selected for areas closer to low‐traffic roads; this is likely because of proximity of low‐traffic roads to high‐quality habitat (Blackburn et al, 2022; Grilo et al, 2015). These patterns in habitat relationships could have been a function of where animals were trapped in combination with a saturation of territories, where territorial interactions affected behavioral patterns.…”