Determining optimal incubation temperature for a head-start program: the effect of incubation temperature on hatchling Burnett River snapping turtles (Elseya albagula)

This study monitored natural nest temperatures and examined the effect of incubation temperature on hatchling phenotype of the freshwater turtle Elseya albagula to determine the optimal temperature for a potential head-start program. Eggs were incubated at constant temperatures (26°C, 28°C and 30°C) to determine the influence of temperature on incubation period, hatchling morphology, swimming performance and post-hatching growth rate. Hatchlings incubated at 26°C had longer plastrons than hatchlings from 30°C and swam faster, three days after hatching, than did hatchlings incubated at either 28°C or 30°C. Incubation temperature also provided a source of variation in hatchling scute patterns. Clutch of origin influenced hatchling mass and size, growth at 184 days after hatching, and the swimming performance of 3-day and 75-day post-hatch hatchlings. Constant temperatures of 26°C and 28°C produced the highest hatching success and highest-quality hatchlings and are therefore recommended for incubation of eggs in a head-start program. In the field, unshaded nests experienced greater daily fluctuations in temperature and higher temperatures overall compared with shaded nests, such that unshaded nest temperatures approached the upper thermal limit to development.