Movement and Reproductive Biology of Female Midget Faded Rattlesnakes, Crotalus viridis concolor, in Wyoming
We studied three populations of the midget faded rattlesnake (Crotalus viridis concolor) in Wyoming to obtain data on reproduction and movements of pregnant females. Pregnant females emerged from hibernation, moved a short distance to a rookery, then moved very little for the remainder of gestation. During this time, females were not observed to forage or mate. Offspring were born between 20 August and 18 September. Mean litter size was 4.7 and was significantly related to female snout–vent length (SVL). Mean offspring SVL = 193 mm, mean offspring mass = 8.0 g; neither was related to female SVL. Litter mass was significantly related to female SVL, suggesting females invest energy into more offspring as opposed to larger offspring. Females appear to reproduce every two to three years. Sex ratio was 1:1 for data collected in 1997 but was significantly female biased for data collected before 1995. These data are compared to those reported for other populations of this species.Abstract
Range of parturition dates and mean annual temperature (C, in parentheses) for five populations of Crotalus viridis. Mean annual temperatures were obtained from the Western Regional Climatic Center (National Oceanic and Atmospheric Administration, U.S. Department of Commerce), the Atmospheric Environment Service (1972), and were estimated from data in Macartney and Gregory (1988). Citations corresponding to these mean annual temperatures are 6.0 C, this study; 6.3 C, Graves and Duvall (1993); 9.9 C, Diller and Wallace (1984); 11.4 C, Diller and Wallace (1996); 12.7 C, Macartney and Gregory (1988)