METABOLIC ACCLIMATION IN 3 SPECIES OF SYMPATRIC, SEMIAQUATIC SNAKES

1. 1. Metabolic rates of brown water snakes (Nerodia taxispilota), northern water snakes (N. sipedon), and eastern cottonmouths (Agkistrodon piscivorus), acclimated to 22 and 32°C, were measured over ambient temperatures of 4-36°C and at 32°C during acclimation from 22 to 32°C. 2. 2. There was statistically significant variation in metabolic rate between acclimation temperatures and among species even though metabolic rate was adjusted for the effects of body mass and ambient temperature and all snakes were collected in the same area. 3. 3. Northern water snakes acclimate more rapidly and to a greater degree than do brown water snakes and eastern cottonmouths. 4. 4. Rate of acclimation in these three species of snakes is a significant function of body mass with small snakes acclimating more rapidly than large ones. 5. 5. Interspecific differences in rate and degree of acclimation suggest that acclimational capability is related to these species' geographic distributions and seasonal variations in behavior. © 1990.