By Susan Milius
During Australia’s dry season, green tree frogs apparently can pull a drink out of thin air.
Even on chilly nights, green tree frogs (Litoria caerulea) unexpectedly turn up outside the warm, cozy tree cavities where they take shelter. Experimenting with frogs in a real tree as well as in a lab version made of PVC pipe shows that chilled frogs get welcome water condensing on them when they hop back inside from the cold, Christopher Tracy of the University of Melbourne in Australia and his colleagues report in the October American Naturalist.
“It’s a mechanism where they can get a little bit of water, and that little bit of water might be very important,” Tracy says. Researchers found that frogs air-cooled below 15° Celsius accumulated 0.03 percent to 0.54 percent of their body mass in condensation. Every drop of water helps during the dry season in the northern part of Australia’s Northern Territory, where from June through August it typically doesn’t rain at all.