Thermal environment, behavior, and body condition of wild Pseudemydura umbrina (Testudines: Chelidae) during late winter and early spring

Pseudemydura umbrina is active only during winter and spring when environmental temperatures are relatively low and the ephemeral swamps that it inhabits contain water. We used operative environmental temperature thermometers to define the microclimates available to P. umbrina in its natural habitat during late winter and early spring, and we monitored the use of these microclimates by seven adult tortoises using radio-telemetry. Although air and water temperatures may be as low as 12-14 C during the day, we found that microclimates available to the animals have operative temperatures of up to 35-44 C out of water and 27 C in water. All animals increased in body mass during this study and females increased in body mass faster than males. Tortoises that spent more time in warm water increased their body mass faster than those that spent more time in cold water. During the cool time of the year, P. umbrina enhances its physiological condition by using warmer microclimates in the range of potential available microclimates.