Temperature and humidity in egg incubation mounds of Varanus rosenbergi

Abstract

Rosenberg’s goanna, Varanus rosenbergi, use the mounds of the termite, Nasutitermes exitiosus, to incubate their eggs on Kangaroo Island. The termite mounds show seasonal temperature cycles both with and without the presence of goanna eggs. Superficially the overall seasonal temperature cycle of a mound resembles that of the ambient temperature (Ta), but mound temperatures are not correlated to daily Ta rhythms. Seasonal temperature variation in a mound containing Varanus rosenbergi eggs was less promounced than without eggs. A mound with eggs had significantly higher temperature during most of the winter (June – August) than in the previous year with no eggs. Mound temperatures fluctuated up to 10.5°C in a six-day period during egg incubation, however temperatures rarely varied more than 2°C within 24-hours. Humidity measured over three consecutive days each month of the year in two mounds showed daily rhythms in 11 out of 12 months for each mound. Humidity in the mounds was not correlated to mound temperature and no daily or seasonal rhythm was detected.