Thermal ecology of the Rattlesnake Crotalus catalinensis from Santa Catalina Island, Gulf of California

Abstract

The body temperature of the Santa Catalina Island rattlesnake (Crotalus catalinensis) is reported for the first time. C. catalinensis presented a broad range of body temperature (13.6 °C - 38.2 °C;  = 25.9 °C; N = 65). The interval substrate temperature associated with the snakes is between 14.8 °C and 37.9 °C, while the ambient temperature ranges from 16.4 °C to 36.2 °C. A higher correlation was found between body temperature and substrate. No significant differences between sexes were observed. The lower active temperature recorded was during March (14.0 °C - 23.7 °C), while the highest temperature occurred in November (19.4 °C - 39.6 °C). The relative humidity recorded was between 53.15% and 77.32%. The open ground habitat without vegetation was the most frequented by snakes. It had been reported that C. catalinensis presented diurnal and nocturnal habits; however, we found that it exhibited only nocturnal habits, even during winter periods. C. catalinensis exhibited, like other rattlesnakes, thermo-conformist behavior, its body temperature correlating with soil temperature; however, the question about whether other rattlesnakes’ pattern of activity is also influenced by relative humidity as it did with C. catalinensis (which is an island species) arises.