Frog hotels: scientists build creative urban shelters to draw species back to Australian cities
Tadpoling is a thing of the past in many suburban creeks, as humans encroach on frogs’ territory. But there is a way to lure them back – frog hotels.
Herpetologist Dr Jodi Rowley, from the Australian Museum, says frogs are the “canary in the coalmine” that suffer first when the environment is toxic.
“Most frog species – not all, but most – are a really great barometer of environmental change. They’re canaries, or bellwethers,” she said.
“Really quite slight changes in their environment can have massive implications.
“I often hear from older generations how much more common frogs used to be … it’s been a slow, gradual decline. Back in the day every cow hoofprint had tadpoles and eggs … that’s not the case any more.”
Rowley is the lead scientist on the museum’s citizen science project, FrogID. The project has collected data on frogs, whose populations are declining rapidly around the world.
The number of frog species in urban areas affected by habitat destruction, pollution, climate change and disease are now less than half than those in adjacent, more natural areas.
“The green tree frog is only just hanging on in the fringes of Sydney,” Rowley said.
“They like messy, flooded areas that we don’t want to look at or deal with.”
In May, Australian National University researchers published an article on how climate change and the spread of chytrid fungus (which causes a deadly disease) affected Australian frogs’ distribution. Amphibians are “disproportionately at risk in the global extinction crisis”, they wrote in the journal Diversity and Distributions. Overall, many species are at risk, although the modelling showed southern frogs at a higher risk than those in the north.
In other recent news, frog populations have been increasing by leaps and bounds thanks to the recent floods in Queensland.
Rowley said there are more than 240 known species in Australia. Six were first described last year, while a new mountain frog that was only discovered this year is already on the endangered list.
Last year, people started reporting dead and dying frogs, mostly in suburban areas in Victoria, New South Wales, and Queensland.
Rowley said the chytrid fungus is involved, but not every frog had it. “It’s a complex murder mystery,” she said. “We’re investigating chemicals, pesticides, fungus … ruling in or out various things.”
People have been saving and freezing frog corpses for the FrogID team, and they’ll be heading out themselves to continue their investigations.
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Meanwhile, she said, it’s easy to make frog hotels, friendly little habitats that will make the amphibians feel safe. Some would even hang out in a dog bowl, she said.
PVC pipes work well arranged on their ends, but only for tree frogs that can climb in and out.
A fish pond or old bath might do, as long as there are ways for frogs to get in and out easily. An old log in a moist place could be a shelter. There must be water, and protection from the sun.
Plants and river stones are optional, according to Wildlife Queensland.
Rowley has made small, dark ponds that appeal to striped marsh frogs, which she said make a noise like a tennis ball “thwocking” against a wall.
“It blows my mind,” she said. “How did they realise that I just put a pond in? Can they smell it?”
“You can build frog ponds and dams and things like that, maybe you can revegetate your local creek or make sure a certain bit of bush is protected.
“Frog hotels are great way to give frogs a sheltered place … not just to breed in but to hang out in.”
There are different rules and advice around tadpoling, she said, because you can easily kill the delicate fledgling frogs and you might spread disease. But making a frog hotel is a way, particularly for children, to safely reconnect with wildlife.
“If you build it, they will come,” she said.