GOPHERUS AGASSIZII (Desert Tortoise). Predation

James L. Boone
SAIC, 1180 Town Center Drive, Las Vegas, NV 89134

Danny L. Rakestraw
SAIC, 1180 Town Center Drive, Las Vegas, NV 89134

Kurt R. Rautenstrauch
Nevada Division of Wildlife, 4747 Vegas Drive, Las Vegas, NV 89108

Natural History Notes: Testudines

GOPHERUS AGASSIZII (Desert Tortoise). Predation. A variety of predators, most notably coyotes (Canis latrans) and common ravens (Corvus corax), have been reported to prey on hatchling desert tortoises (Ernst et al. 1994. Turtles of the United States and Canada. Smithsonian Institution Press, Washington, D.C. 578 pp.). Here, we report an observation of a hatchling tortoise, fitted with a radiotransmitter, that was preyed upon by native fire ants (Solenopsis sp.) in the eastern Mojave Desert at Yucca Mountain, Nevada (36 degrees 50 minutes N, 116 degrees 25 minutes E). On 27 August 1993, we found a live, 5 day-old, desert tortoise (carapace length = 45 mm) with the eyes, chin, and parts of the head and legs being eaten by ants. The tortoise was lethargic and responded little when touched. The ants were removed, and the tortoise was released near the site of capture. When relocated the next day, the tortoise was dead. This specimen was deposited at University of California at Berkeley, Museum of Vertebrate Zoology (#MVZ 223521). Eight of 74 other radiomarked hatchlings (aged 3-7 days) monitored at Yucca Mountain during 1992-1994 were found dead with fire ants scavenging their carcasses. We do not know if the ants killed these tortoises or if the ants were simply scavenging. These specimens were also deposited at the Museum of Vertebrate Zoology. While imported fire ants (S. invicta) have long been known to kill hatchling gopher tortoises (G. polyphemus; Mount 1981. J. Alabama Acad. Sci. 52:71-78), native fire ants have previously not been implicated as predators of desert tortoises.

Submitted by James L. Boone, Danny L. Rakestraw, and Kurt R. Rautenstrauch, Science Applications International Corporation (SAIC), 1180 Town Center Dr., Las Vegas, Nevada 89134, U.S.A. eMail address of senior author: jim_boone@ymp.gov

Tortoises were handled under permits PRT-683011 and PRT-781234 from the U.S. Fish and Wildlife Service, and S-0446, S-1595, S-3108, S-5041, S-6941, and S-9060 from the Nevada Division of Wildlife. This research was supported and managed by the U.S. Department of Energy, Yucca Mountain Site Characterization Office, as part of the Civilian Radioactive Waste Management Program under contracts DE-AC08-88NV1067, DE-AC08-93NV11267, DE-ACO1-91RW00134, and DE-ACO8-91RW00134.