A NEW ROAD CROSSING STRUCTURE FOR SMALL ANIMALS: CASE STUDY WITH THE YOSEMITE TOAD.
Cheryl S. Brehme; US Geological Survey; 4165 Spruance Road, San Diego, CA, 92101; (619) 225-6427; cbrehme@usgs.gov; Stephanie L. Barnes, Robert N. Fisher, Cheryl S. Brehme and Stephanie Barnes
Many small animal populations, especially amphibians that must migrate between aquatic and terrestrial habitats, are susceptible to negative impacts from roads within their habitat. Over a 4-month period in 2017, Sierra National Forest recorded 92 Federally threatened Yosemite toad (Anaxyrus canorus) mortalities along a single forest service road. Narrow tunnels with directional barriers are a standard mitigation solution to reduce amphibian road mortality. However, these systems may act to filter migratory movements of populations that disperse over large areas. In 2018 we tested a new and novel passage prototype, an 8-inch high elevated road segment using road mats designed for use by heavy equipment at construction sites. The prototype was installed on top of the road along a toad mortality "hotspot" with directional barrier fencing, and provides a safe crossing nearly 100 feet wide while allowing both light and rain to pass through. We monitored toad activity along fencing and under the passage using specialized cameras and conducted regular road mortality surveys. Initial results show that toads used the passage and mortality was greatly reduced. This study supports a broader research program to inform best management practices for barrier and crossing systems for sensitive amphibians and reptiles in California.
Ecology and Conservation of Amphibians and Reptiles I