Comparative Ecology of the Mottled Rock Rattlesnake, Crotalus lepidus, in Big Bend National Park

Beaupre, Steven

Environmental factors that influence geographic variation in life history have both direct and indirect effects on time-energy budgets of individuals. The exact relationships between environmental factors and time-energy budgets of snakes remain relatively unexplored. I studied two populations (Boquillas: area B, and Grapevine Hills: area G) of the mottled rock rattlesnake (Crotalus lepidus) in Big Bend National Park, Texas. Area B is hotter, drier, and less productive than area G. I used mark-recapture and radio telemetry to study age specific size, reproduction, surface use, movements, diet, and body temperatures of snakes from these sites. Adult snakes from area B had smaller age specific body masses and snout-vent lengths, lower frequency of surface use, higher average body temperature, and lower probability of defecation than snakes from area G. These observations suggest that resources for growth may be limited to a greater extent at area B. High environmental temperatures at area B may limit foraging time (therefore energy harvesting) and increase body temperatures (which influence maintenance metabolism) to a greater degree than at area G. Ongoing tests of these hypotheses may clarify relationships between environmental factors, time-energy budgets, and life history traits of snakes in these populations.

Comparative Ecology of the Mottled Rock Rattlesnake, Crotalus lepidus, in Big Bend National Park

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