James Cook University researchers have tested frog housing and nursery preferences in the Wet Tropics rainforest of North Queensland, with frogs finding the thermal regulation of concrete shelters to be the perfect tropical retreat.
New research published in the journal Ecology and Evolution, describes the use of artificial concrete and wooden homes by tiny elusive ground dwelling native Robust Whistling frogs (Austrochaperina robusta).
Hundreds of the wild frogs used their new homes throughout their whole life-cycle, from egg to juvenile to adult, demonstrating new ways to monitor and conserve frogs.
Lead author and JCU PhD candidate Jordy Groffen described designing the new frog homes to match the types of natural habitats these frogs would typically use.
"We knew they normally live under rocks and logs … so we found fallen trees on-site and chopped them into the right size," he said.
"The concrete ones were made here at the University. They're boulder-sized and have six chambers with multiple passages … like six-pack apartments. Some of them had beautiful moss growing over them.
"The frogs liked the shelters more than we expected. It's a new non-invasive way to monitor and help frog populations".
Mr Groffen said they had over 800 observations of frogs, with the highest being 45 frogs in a single survey.
"Although they used them straight away, it still took two years before they bred in them … they had to settle in a bit. But when they did breed in them, they loved it," he said.
"We found both males and females and we also found eggs in them. We had one male with three nests in a single season. That was great because we know very little about their egg stage."
Frog monitoring is usually done by listening to mating calls, which are only made by adult male frogs. This makes studying frog life cycles and egg laying challenging.
"Normally you only find eggs by flipping things over, which can damage the micro habitat. There's a chance you might hurt the frogs or their eggs," Mr Groffen said.
"These frogs are only two centimetres long and brown, living in the leaf litter. We thought that if we make something they actually enjoy, they might come to us instead."
Mr Groffen explained how the researchers used tiny micro-temperature loggers to better understand the influence of weather conditions on frog housing preferences.
"In the winter or dry season in Paluma it can still get below 10 degrees. The concrete shelters warm up bit more and stay warmer for longer, a bit like passive housing," he said.
"Previously we didn't even know where they were in the dry season. Now we know there are more frogs under the concrete shelters in the dry season than in the hotter wet season."
While the frogs in this study are not threatened, other species of ground frog face threats from climate change, pig disturbance and habitat restrictions.
"The endangered Bellenden Kerr nursery frog lives in similar habitats, but only on top of one mountain," explained Mr Groffen.
"This gives us new tools to help protect them."
