Emergence behaviour of yacare caimans (Caiman Crocodiles yacare) in the Brazilian Pantanal

Abstract

We studied the emergence and basking behaviour of Pantanal caimans (Caiman crocodilus yacare) in relation to temperature. In the cold season, caimans were exposed to the sun, and air temperatures higher than water temperatures suggest that emergence behaviour may be due to thermoregulation. In the dry season, most (66%) emergent caimans were found in the shade between 1000 and 1500, and body temperatures rarely exceeded water temperatures. Caimans also emerged at night, although body temperatures were highly correlated (r=0.974, P<0.001) with water temperatures, suggesting that emergence is related to factors other than thermoregulation.