Thermoregulation of captive Caiman latirostris (Alligatoridae)

Abstract

We investigate if thermoregulatory patterns of captive broad snouted caiman, Caiman latirostris, changes in response to different thermal situations. We implanted subcutaneous dataloggers on eight adult females and distributed four copper models filled with water to measure operative environmental temperatures exposed to the sun (T<inf>s</inf>), at the shadow (T<inf>sh</inf>), at the water (T<inf>w</inf>) and at the water ponds (T<inf>p</inf>) located inside the caiman pen. Maximum Tb correlated inversely to body mass, implying a social hierarchy. Tb presented a sinusoidal pattern during sunny and rain days. In sunny days, Tb ranged from 21 to 36.2ºC and changed mainly following T<inf>w</inf>or T<inf>p</inf>. Whenever T<inf>w</inf>or T<inf>p</inf>started to decrease before Tb reached about 34°C, caimans moved to sun exposure to bask, mostly during the hottest hours of the day (beTween 12:00 and 15:00h) until Tb reached 34ºC, when it returned to water. During the night, Tb varied according to T<inf>w</inf>or T<inf>p</inf>. During rainy days, Tb ranged beTween 22.1 and 28.6 °C and followed T<inf>w</inf>or T<inf>p</inf>, indicating that caimans spent most of the time into water. These data demonstrate that C. latirostris behaves as an active thermoregulator during periods with abundant heat source, and as a thermoconformer when it is scarce.