Green tree frogs remain active in northern Australia during winter, despite a seasonal lack of rain and surface water. It seems that the frogs (Litoria caerulea) get around this by absorbing water that condenses on their skin — increasing their body mass by up to 0.93%.

Christopher Tracy and his colleagues at Charles Darwin University in Darwin, Australia, used ice water to cool frogs to 7–16 °C. They then moved the chilled animals into humid, warm (up to 30 °C) natural and artificial tree hollows, where they observed droplets of condensation on the creatures' dorsal skin, especially on their heads (pictured).

The authors suggest that when the frogs leave their warm shelters on cool nights, they gain more water on their return than they lose through evaporation while they are outside.

Credit: C. R. TRACY

Am. Nat. 10.1086/661908 (2011)