Singin’ in the rain: The song of the Cape rain frog

For DAVE PEPLER, there’s no more evocative sound than the song of the Cape rain frog heralding the approach of autumn.

“When disturbed or angry, rain frogs blow themselves up into
a nearly round ball, eyes popping and limbs flailing.
This is an attempt to scare off potential predators, but the result is
merely comical, a cruel caricature of the soprano of the soil.”

In a fit of pique, the normally mild-mannered scientist and systematist Carolus (Carl) Linnaeus described frogs thus in 1758: “These foul and loathsome animals are abhorrent because of their cold body, pale colour, cartilaginous skeleton, filthy skin, fierce aspect, calculating eye, offensive smell, harsh voice, squalid habitation and terrible venom; and so their Creator has not exerted his powers to make many of them.”

Poor old Carolus. How patently clear it is now that he never travelled from his home in Sweden to the Cape, since if he had, he would surely have commented on the sweet voice of the Cape rain frog. But he did describe the species, also in 1758, from a specimen that in all likelihood was collected by Ryk Tulbagh, who regularly sent parcels of flora and fauna from the Cape to the great man in Uppsala. The frog’s scientific name, Breviceps gibbosus, is an apt description of a creature with a short (brevi) head (ceps) and a hump (gibbosus). 

How blessed we are in South Africa to have 169 frog species, varying from the platannas – widely used in pregnancy tests in days gone by – to the pallid ghost frogs of mountain streams. Even the Western Cape, not known for its animal biodiversity, has a healthy frog population, whose calls range from the clicking of stream frogs to the typically loud croaking of the raucous toad. But my all-time favourite is the rain frog, that plaintive underground singer heard at the approach of a cold front.

The Cape rain frog is classified as Vulnerable on the IUCN’s Red List, since most of its natural habitat of renosterveld has been converted into oceans of monoculture. Its range is now restricted to fragmented islands of natural vegetation and, luckily for us, suburban gardens. Here, if the soil is friable and well drained and has enough organic material, you will find this elusive amphibian.

With the seasons…

All summer long the rain frogs sleep. In a state known as aestivation, they buffer themselves from desiccation by secreting a mucous cocoon around themselves, including little plugs in their noses. They hardly breathe, their heartbeat slows down dramatically and for months on end they are in suspended animation, waiting for the autumn rains. Then, the day before a cold front arrives, their summer sleep is broken, prompted by the sudden change in air pressure. They move towards the surface and from beneath the shelter of fallen leaves they begin to call. These calls are highly ventriloquial and it is practically impossible to find the frogs simply by trying to trace them. You can pinpoint the call station, however, by cupping your ears with your hands and if you move very quickly, you may surprise the little chorister.

The frogs burrow backwards with their hind legs and the dark tunnels they create are where they spend their lives. They are thus extremely important creatures of the soil, aerating it to deeper levels and providing passage to other fossorial organisms. During mating – known as amplexus in frogs – the male glues himself to the back of the female and fertilises the eggs as they appear. She then deposits a clump of pearly eggs into a special chamber she has prepared and the tadpoles develop there without any standing water. When disturbed or angry, rain frogs blow themselves up into a nearly round ball, eyes popping and limbs flailing. This is an attempt to scare off potential predators, but the result is merely comical, a cruel caricature of the soprano of the soil.

I know that some people are irritated by a loud chorus of frogs in the garden, especially when there is a pond close to a bedroom. But the rain frog is in a totally different class when it comes to singing. I am reminded of birds rather than frogs when I hear its croup-croup-croup call and I find it immensely soothing, knowing the rains are coming.

Should you wish to have Cape rain frogs in your garden, prepare a sheltered corner by digging it over well and then mulching the surface with leaves, especially oak. Ask your neighbours for a frog donation, especially if they own properties with swimming pools, where these amphibians tend to get trapped. Gently transfer the frogs to the prepared spot – and wait. Then, as leaves begin to scuttle in the warm wind of an approaching cold front, your garden choir will start up. Forget the bullfrogs, forget the stream frogs, for you will now have your own hidden choir, singing a nocturne to your dark garden.

Dave Pepler is a specialist tour guide for Live the Journey. To join him on his one of a kind and fascinating travels, contact Live the Journey at info@livethejourney.co.za.


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