Refuge Use in a Patagonian Nocturnal Lizard, Homonota darwini: The

AGUILAR, ROCÍO; CRUZ, FÉLIX BENJAMÍN

JOURNAL OF HERPETOLOGY

SOC STUDY AMPHIBIANS REPTILES

Año: 2010 vol. 44 p. 236 - 241

0022-1511

ABSTRACT.—The thermal quality of diurnal refuges is important to the performance and survival ofnocturnal reptiles. We studied refuge use on both slopes of an east–west-oriented hill by the thigmothermicgecko Homonota darwini, the southernmost-distributed nocturnal lizard in the world, in the vicinity ofBariloche, Rio Negro, in the Patagonia of Argentina. Because of the harsh climatic conditions in Patagonia,suitable refuges are limited, and retreat-site use is important for these geckos. Homonota darwini usedrefuges significantly more frequently on the warmer western slope in our study site. Geckos on the westernslope used those refuges with higher temperatures regardless of size and thickness of rocks that acted asretreats. We tested whether refuge temperature affected locomotor performance of these lizards. Performanceexperiments showed that maximum sprint speed was affected by the temperature of the refuges. Refuges at22.5uC allowed lizards to achieve their fastest sprint performance. Unexpectedly, sprint performance oflizards that used refuges with temperatures .32uC was the lowest among all tested refuge temperatures (18u,22.5u, 27.5u, and 33uC). Our data illustrate the importance of the thermal quality of refuges for reptiles livingin extreme environments.