Highway Crossing Rates of Wild Felids Before, During, and After Wildlife Crossing Structure Installation

Area of Science:

• Wildlife ecology
• Conservation biology
• Road ecology

Background:

• Roads fragment wildlife habitats and increase mortality, particularly for endangered species like the ocelot.
• Wildlife crossing structures (WCS) are implemented to mitigate these impacts and maintain habitat connectivity.
• South Texas faces significant ocelot mortality due to vehicle collisions on roads like Farm-to-Market Road 106 (FM106).

Purpose of the Study:

• To assess the effectiveness of eight newly installed WCS and associated fencing in reducing wildlife-road interactions.
• To evaluate the usage rates of WCS by GPS-collared ocelots and bobcats before, during, and after construction.
• To analyze factors influencing on-roadway crossings versus WCS usage in an endangered species habitat.

Main Methods:

• GPS-collared ocelots (Leopardus pardalis) and bobcats (Lynx rufus) were tracked between 2013 and 2021.
• Camera traps verified WCS usage, supplementing GPS data.
• On-roadway and WCS crossing rates were compared, controlling for proximity to FM106, time of day, and traffic levels.

Main Results:

• A general decline in total and on-roadway crossings of FM106 was observed for both species over the study period.
• Bobcats documented 37 crossings using WCS, but on-roadway crossings remained more frequent post-construction.
• Animals crossed roads faster than WCS, especially on bright nights, and slowed in high traffic, indicating behavioral adjustments.

Conclusions:

• Wildlife crossing structures may require extended periods for animals to acclimate, suggesting usage could increase over time.
• While WCS show promise, on-roadway crossings persist, highlighting the need for comprehensive mitigation strategies.
• Additional fencing may be crucial to further reduce high-risk road encounters for ocelots in this critical habitat.