The desert rain frog, a unique amphibian native to a narrow coastal strip of south-west Africa, has been classified as vulnerable on the International Union for Conservation of Nature (IUCN) red list. Without conservation efforts, its population is expected to decline by 20% in the next decade, the IUCN warns.
A unique species adapted to desert life
The desert rain frog (Breviceps macrops) lives only in the north-west coast of South Africa and south-western Namibia. It cannot be found anywhere else on the planet, according to experts. With a rotund body and stumpy legs that dig rather than jump, it has evolved to survive in the unforgiving dunes of the southern African desert.
“It’s a completely unique species and it’s just amazing that it has managed to evolve and adapt to this harsh environment,” says Dr Jeanne Tarrant, executive director of Anura Africa and co-chair of the IUCN Amphibian Specialist Group. “It [exhibits] the least typical frog kind of behaviour that you can get. Frogs like it where it’s moist and tropical – and this thing is living in the desert.”
Threats from mining and development
The IUCN warns that diamond mining and development projects, such as the Boegoebaai port and rail project, are expected to affect a third of the frog’s range in South Africa and two-thirds of its range in Namibia over the next 20 years. Increased urbanisation also poses a threat.
There are added concerns that the frog may be a growing target for the pet trade, after social media videos featuring its famous squeak were shared widely online. The high-pitched noise, which sounds like a dog toy, is actually a distress call, usually made in response to predators, says Tarrant: “Someone would have been poking it with a stick or traumatising it a bit to get it to make that call.”
Unique biology and behaviour
The frog spends much of its time burrowed in sand dunes, emerging at night to snack on termites and other insects. “Their back feet are their little shovels and they will burrow down and disappear within seconds,” says Tarrant. The sand on the surface is bone dry, so the frog tunnels down backwards about 30cm until it finds a damp layer.
Louis du Preez, professor of zoology at North-West University in South Africa and leader of the African Amphibian Conservation Research Group, says the frogs can remain underground for months, living off oxygen in the soil. When they resurface, they search for patches of water formed by condensed fog and absorb moisture through their stomach, which has a highly vascularised pink patch that acts like blotting paper.
“If it had a long, thin body like a snake, this would mean a bigger surface area, increasing the risk of moisture loss through evaporation,” says Du Preez. “This little fat froggy can survive better.”
Reproduction and conservation
To reproduce, the male frog secretes a glue on his chest and forearms and attaches himself to the female. The female then digs into the soil to deposit eggs, which the male fertilises. On top of the fertilised eggs, the female lays unfertilised eggs that later liquefy, and the tadpoles whip this liquid into a foam that traps oxygen.
“Among all the frogs in the world, this one has got really unique breeding, biology, physical features, morphology,” says Du Preez, adding that conserving sand dunes is the best way to protect the species. “They don’t occur anywhere else in the world.”
