CAMERA TRAP MONITORING OF CULVERT USAGE UNDER VASCO ROAD WITH EMPHASIS ON CALIFORNIA RED-LEGGED FROGS AND CALIFORNIA TIGER SALAMANDERS.
Travis WC McCleary; Sapere Environmental; 135 Glasgow Circle, Danville, CA, 94526; (925) 719-1916; tmccleary@sapereenv.com; Jerry Roe

Culverts are an effective tool to decrease the effects of habitat fragmentation posed by busy roads and provide a means for safe passage for a variety of wildlife species. Eight culverts were installed under a one-mile segment of Vasco Road in eastern Contra Costa County, California in conjunction with a Caltrans Local Assistance road safety improvement project to increase road permeability and decrease road mortality. Various box and pipe culvert designs were constructed with variable angles and line of sight configurations. Time-lapse and passive infrared trail cameras were deployed on seven selected culverts to evaluate wildlife usage and efficacy with an emphasis placed on California red-legged frogs (Rana draytonii) and California tiger salamander (Ambystoma californiense). Trail cameras were deployed during two consecutive wet seasons, from January 27, 2017 to July 4, 2017, and November 2, 2017 to May 31, 2018, for a total of 2,979 trap nights. Data were analyzed to quantify capture events, images, and culvert crossings; frequency of use by species; and performance of camera configurations (time lapse vs. motion detection) across taxa. A total of 4.41 million photos recorded resulted in 7,208 total capture events, including 47 California red-legged frog capture events (1,035 images) and 14 California tiger salamander capture events (173 images). Thirty-two species were documented using the culverts with 9.86% of non-rodent capture events resulting in successful crossings. No crossing events were recorded for California red-legged frogs or California tiger salamanders; however, behavioral responses exhibited by reptile and mammal species suggest individuals spend little time within culverts during crossing events, and images indicate wildlife utilize culverts for other functions. Further study is needed to determine how amphibians use culverts and how culvert design can be improved to facilitate amphibian crossings.

Wildlife Techniques and Technologies