A test of the use of gray wolf (Canis lupus) urine to reduce coyote (Canis latrans) depredation rates on loggerhead sea turtles (Caretta caretta) nests

Abstract

Loggerhead sea turtles (Caretta caretta) are currently listed as vulnerable, with a decreasing population trend, by the International Union of Conservation of Nature. From 2015 to 2019, coyotes (Canis latrans) depredated 24.12% of loggerhead nests on the night they were laid on South Island beach at the Tom Yawkey Wildlife Center, near Georgetown, SC, resulting in an estimated 3816 eggs lost each year. Over that time, a South Carolina Department of Natural Resources Turtle Technician Team patrolled the beach at dawn every morning to cage and catalog loggerhead nests and eggs but were unable to cost-effectively protect the nests the night the eggs were laid. To test a new method to dissuade coyote depredation, we used dispensers filled with gray wolf (Canis lupus) urine to simulate wolf activity on seven sections of the beach and left seven sections untreated as controls. We observed a significant reduction in depredation rates where urine was present relative to control areas (G-test adjusted with the Williams correction, G = 5.749, df = 1, p = 0.0165). The results suggest this may be an example of exploitative competition in the absence of interference competition. With daily teams already patrolling the beaches, using wolf urine as a deterrent could be an inexpensive, non-invasive way to reduce coyote depredation on loggerhead and other sea turtle nests elsewhere.