Pronounced daily heterothermy in the White-throated Treecreeper Cormobates leucophaea

Torpor, a controlled reduction in metabolism and body temperature, reduces energy expenditure substantially. However, torpor expression in wild passerines is currently understudied. We show that skin temperature (T s ) of resting White-throated Treecreepers ( N = 4) fell by ~ 5 °C on average in both summer and winter, independent of ambient temperature, but we could not confirm torpor use (T s reduction > 5 °C). It is possible that roosting in tree hollows provides sufficient insulation to minimise energy loss, or torpor is used only during extreme conditions. Further studies are needed to characterise the physiological flexibilities of species and, therefore, their capability to cope with changing environmental conditions.