Size and winter survivorship in neonatal western rattlesnakes (Crotalus viridis)

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Abstract
The interaction between size at birth and early survivorship has received considerable theoretical attention in a variety of taxa. However, collecting empirial data to test these hypotheses has proved difficult, especially among ectotherms such as snakes. In this study, I examined winter survivorship of neonatal western rattlesnakes (Crotalus viridis) with respect to size at birth and site of hibernation. I collected 115 neonatal C. viridis in the fall of 1985, divided the sample into two groups, and released them to hibernate at two winter dens. Recaptures suggest that minimum survivorship during the winter of 1985 – 1986 was about 55% and that survivorship was independent of both weight and condition at birth. Young released at the two dens differed in both the pattern and amount of weight loss but not in survivorship. My results suggest that any survival advantage conferred by size at birth either varies annually or occurs during the first active season when food for small snakes may be difficult to obtain.