MCCLEARY, R. J. R. *; LILLYWHITE, H. B.; MCCUE, M. D. ; University of Florida, Gainesville; University of Florida, Gainesville; University of Arkansas, Fayetteville: Foraging and Water Requirement in Terrestrial Cottonmouth Snakes

Cottonmouth snakes (Agkistrodon piscivorus conanti) inhabiting the Cedar Keys of Florida are terrestrial and dependent on condensation or rainfall for drinking water. Field studies indicate that snakes lose body water between rainfall events and are active at deficits up to 12 % of body mass. These snakes feed on marine fish that are dropped or regurgitated by nesting sea birds, which compounds the osmotic problem related to dehydration. During a prolonged drought when snakes were inactive, we found individuals in holes beneath ground with body water deficits averaging 16% of hydrated body mass. In the laboratory, we determined the critical water deficit at which snakes exhibited sluggish movement and flaccid skin on the posterior body, nearing death if the dehydration had continued. The mean critical deficit measured in 9 snakes was 33.8 � 2.4 % of initially hydrated body mass. Snakes refused to eat fish at a mean water deficit of 22.9 � 4 % of initial mass, but did so following drinking and recovery of water balance. Measurements of oxygen consumption suggest there is no significant depression of standard rates of metabolism during dehydration to critical water deficit. We conclude that during drought conditions both energy and water are conserved primarily by inactivity and seclusion below ground. However, inactivity separates snakes from food resources (fish carrion) that are ephemeral in these insular habitats. In the wild, snakes drink water from several sources including pools or wet surfaces on leaves, water from rainfall that collects on the head while it is held upright, and body surfaces that collect rainwater when a snake is coiled. Condensation appears to provide an additional sporadic source of fresh water.