To Forage, Mate or Thermoregulate? Influence of Food Supplementation on an Imperiled Rattlesnake (Sistrurus Catenatus)

Due to low energy demands and infrequent feeding, little is known about potential fitness trade-offs for temperate pitvipers which must balance remaining stationary to acquire and digest food while traversing large areas to procure mating opportunities. We radio-tracked 16 male easterm massasauga rattlesnakes Sistrurus catenatus from May to August 2014 in northern Michigan, half of which were fed a supplement diet of mice. We compared body condition, space and habitat use as well as thermoregulatory behavior between the two treatments. Fed snakes had higher post-reproductive body condition scores than naturally foraging controls by the end of the study. Microhabitat selection and movement patterns of fed snakes did not differ from controls during the breeding period. Controls had higher diurnal body temperatures than fed snakes, but neither group differed in their accuracy or effectiveness of thermoregulation. Our results suggest the behavioral demands of finding mates exerts substantial pressure on males, causing them to largely forgo stationary digestion in exchange for increasing the prospect of reproducing. Given the infrequent reproductive rates of female massasaugas in northern latitudes, intense mate searching by males may be a fixed behavior in these populations, regardless of food intake