Herpetological Review 50, Natural History Notes: Gopherus Polyphemus Predation

Authors: Danielle, K. Walkup, Toby J. Hibbitts, Wade A. Ryberg, Roel R. Lopez, Bruce W. Hagedorn, Jeremy R. Preston, Wayne Pittman and Justin T. Johnson

GOPHERUS POLYPHEMUS (Gopher Tortoise). PREDATION.

Gopherus polyphemus is listed as a threatened species by the Florida Fish and Wildlife Commission (Florida Wildlife Code Chap. 68A-27 F.A.C), and the eastern population (including Florida) is under consideration for listing as threatened by the US Fish and Wildlife Service (USFWS 2011. Federal Register 74:46401–46406). Canis latrans (Coyote) are invasive in Florida, and have been expanding their range across the state (Hill et al. 1987. Wildl. Soc. Bull. 15:521–524; Thornton et al. 2004. J. Mammal. 85:973–982). Here we report on the predation of an adult G. polyphemus by C. latrans. At 2031 h on 4 April 2018, a camera trap (Reconyx PC800 Professional) set to trigger on motion detection captured an image of an adult C. latrans carrying an adult G. polyphemus in its mouth (Fig. 1). The camera was set to capture bursts of three pictures 5 seconds apart, with the C. latrans and G. polyphemus captured only in the first picture of the three. This camera was located on the fence-line of a soft-release enclosure for translocated G. polyphemus in Okaloosa County, Florida (30.47535°N, 86.76312°W; WGS 84), as part of a paired design of cameras located inside, on the fence, and outside of the enclosure, to capture images of potential predators. Although we have no direct proof that the G. polyphemus in the picture was killed by the C. latrans, we suspect this tortoise was a female that had been encountered in late February at a burrow near the fence camera that captured the picture. In early May, the remains of that female were found on the outside of the enclosure between the fence camera and the paired outer camera. Canis latrans are considered predators of hatchling and juvenile G. polyphemus (Smith et al. 2013. J. Wildl. Manag. 77:352–358; Dziadzio et al. 2016. J. Wildl. Manag. 80:1314–1322). Previous reports of predation by C. latrans on G. polyphemus include finding the gular projection of the plastron from a two to three-year-old G. polyphemus in C. latrans scat (Moore et al. 2006. Herpetol. Rev. 37:78–79). While many other predators are thought to prey on eggs, hatchlings, and juveniles (e.g. snakes, birds, mammals; Butler and Sowell 1996. J. Herpetol. 30:455– 458), there are fewer known predators of adult G. polyphemus, although predation on an adult G. polyphemus by feral dogs has been reported (Causey and Cude 1978. Herpetol. Rev. 9:94–95). The effect of predation on translocated G. polyphemus is not well documented, but long-lived, slow growing species like G. polyphemus are particularly impacted by the loss of adults in the population, so predator management is likely important for at least the initial maintenance of these populations (Ashton and Burke 2007. J. Wildl. Manag. 71:783–783; Tuberville et al. 2008. Biol. Conserv. 141:2690–2697).