Nick Evans, a Durban snake rescuer, encountered the rare spotted shovel-nosed frog during a survey in Zimbali Estate on the KZN north coast. | Nick Evans
Image: Nick Evans
FROG watching might not be as popular as birding, but that might soon change following the launch of a new app designed to help users identify the amphibians croaking outside.
The app, known as Frogs of Southern Africa, was developed by Professor Louis du Preez in collaboration with herpetologist Vincent Carruthers.
Du Preez says the app grew out of his book, Field Guide to the Frogs of Southern Africa, which took four and a half years of research to complete.
“Amphibians were the first animals to colonise land 350 million years ago and now they are in trouble. They are the most threatened vertebrate group. I just felt compelled to do something and reach out to the public,” he said.
You can download the free version of the frog app by clicking on the QR code.
Image: Supplied.
The “lite version” of the app is free to download, while the extended version is available for R300.
From the croaky “kwaark” of the Common River Frog to the duck-like quack of the Raucous Toad (Sclerophrys capensis), Du Preez says each entry is presented in English, Afrikaans, and scientific terminology. The app also features geo-referenced tools that allow users to identify which frogs occur where, whether in their back garden or at a planned destination. A photographic key further assists identification, making it valuable to both researchers and amateurs.
Du Preez says a major advantage of the app is that it allows for an unlimited number of photographs, especially useful for frogs with colour variation. It also includes the ability to play the call of each frog.
“Each frog has a species-specific unique call,” he said.
The app includes video clips of frogs, a complete catalogue of all frog species in Southern Africa, and a GPS function that lets users generate a list of frogs they can expect in their area.
“It's just a way to reach out to the general public and sensitise them about frogs,” said Du Preez.
He acknowledges that frogging may never rival birding in popularity. “Frogging will never be at the same level as birding. Because birding you can do in the daytime and late afternoon, where you can sit with your binoculars. To really study frogs you have to go out at night and sometimes in muddy areas and so on. You can't expect an elderly person to suddenly start frogging but you can hear the frogs and with the app, identify them and then get to know them.”
There are currently 173 known frog species in Southern Africa, with 132 found in South Africa. However, recent discoveries are expected to bring the total to 180.
“To put it in perspective, there are less than 10 frogs native to the UK and they have a few that came in from Europe, but we sit with 180, all of which are native to this area and the majority of them don't occur anywhere else in the world, they’re endemic to this area,” Du Preez said.
Known as “the frog professor,” Du Preez notes that the most endemic frogs are often found in the smallest geographical areas, particularly in the Western Cape. The diversity increases along the East Coast into KwaZulu-Natal, with the highest diversity in Zululand, northern KZN, and parts of Mpumalanga and Limpopo.
“In Namakwaland, you might find three species of frogs that are common there, whereas in parts of Zululand, you will find 40 and more at a single location.”
Habitat destruction, he says, is the main reason frog numbers are in decline.
“We find quite a number of frogs that are restricted to very small geographical areas. For example, we have a frog that you only find on one side of Table Mountain, and nowhere else in the world. There's a frog that's only present on Caledon Mountain. There's a frog that you only find in the Elandsberg Mountain near Port Elizabeth.”
Chemical pollution, pesticides, and herbicides also threaten frogs.
“In some parts of the world, frogs are being eaten in vast numbers. Luckily, it's not a huge problem for us in South Africa. There are frogs that have been eaten, but not in the numbers of Indonesia and parts of Europe like north-eastern France,” said Du Preez.
He encourages people to appreciate frogs and look out for them, and says one way of doing so is to create a small water garden at home.
“But then, don't go and collect frogs and bring them there. The frogs will find it on their own. But if you create a little garden pot with some vegetation, very soon, there will be frogs there and it's been shown to have a calming, soothing effect if you hear a chorus of frogs at night, provided that it's not under your bedroom window.”
Du Preez who is based at the North-West University, is a parasitologist and herpetologist who focuses his research on amphibians and their parasites. Recently he was honoured for his work when a parasitic flatworm found in the eye of an alligator was named after him, following decades of research. The name which made him laugh: Latergator louisdupreezi.
In 2023, a newly discovered Malagasy frog species was named after him. The honour was bestowed by a group of German scientists, in recognition of du Preez’s substantial contributions to understanding the flatworm parasites of Malagasy anurans. The new species is now formally named and described as Blommersia dupreezi.
North-West University says that naming species after scientists is a long-standing tradition in biology, both as a mark of respect and, occasionally, gentle mischief.