Circadian Metabolic Cycles in Eastern Cottonmouths and Brown Water Snakes

During a review of recent literature on respiratory metabolism of snakes, we found that less than 50% (11/24) of published studies reported the time of day or phase of the photoperiodic cycle within which metabolism was measured and one-third of these studies did not report the photoperiod under which experimental animals were kept. As part of preliminary studies for analyses of metabolism of several species of snakes, we found significant daily variations in standard metabolic rates (the energy used by "fasting animals resting in the dark in the inactive phase of their diurnal cycle") of the brown water snake (Nerodia taxispilota), and eastern cottonmouth (Agkistrodon piscivorus). Here we report those findings.