/ 24 July 2021

Big mission to save tiny frog

Pickersgill's Reed Frog, Hyperolius Pickersgilli, Richards Bay, Kwazulu Natal, South Africa
To the rescue: An endangered Pickersgill’s reed frog perches on a leaf near Richards Bay. (Morgan Trimble)

Most people have probably never heard of a Pickersgill’s reed frog, but Ian Du Plessis would like that to change.

At 2.5cm, and no bigger than a R5 coin, these endangered, rare amphibians are endemic to South Africa, but only exist in a narrow stretch of coastal wetlands in KwaZulu-Natal.

These frogs, says Du Plessis, who is the curator of reptiles, fish, insects, amphibians and arachnids at the Johannesburg Zoo, feed on malaria-carrying mosquitoes and are an important indicator species signalling the health of coastal wetlands.

Du Plessis is part of a team of conservationists from the zoo, the Endangered Wildlife Trust and Ezemvelo KZN Wildlife, who run the pioneering amphibian conservation project.

Since 2018, they have released about 800 offspring, bred in specially-designed laboratories at the zoo, into their natural habitat in KwaZulu-Natal.

“We release them once a year,” he says. “We go and collect 20 to 30 wild specimens, bring them to the zoo and let them breed and then all the offspring plus the wild specimens are taken back to the place of origin and are released, reinforcing populations under stress.”

Du Plessis has led 10 to 15 expeditions to monitor the released batches of frogs, who are marked with colour coded and patterned frog markers, making them glow in the night. “We found them and they survived, so the programme we have initiated for the preparation to survive within a natural environment is working.”

Pickersgill’s frogs are found in a 1 000km stretch from St Lucia to Port Shepstone. There are about 48 small wetlands where they are known to occur, he says.

In June 2017, Edna Molewa, the environmental affairs minister at the time, approved and gazetted a biodiversity management plan specifically for the species. 

“This is an official document recognised internationally about a species that is not only endemic, but occurs nowhere else in the world except KwaZulu-Natal but plays such a big role in the biodiversity in South Africa,” says Du Plessis.

Until a few years ago, Pickersgill’s frogs were classified as critically endangered because of the destruction of their habitat, which is driven by coastal development, pollution, agricultural development and the spread of invasive species. 

“Now,” he says, “they are only listed as endangered purely because of new habitat that was found.

The project creates an “insurance population” in the event where a population goes extinct. That unfolded in 2017, when a population at the old airport in Durban next to Amanzimtoti was wiped out because of habitat destruction and pollution.

“There’s so much we don’t know about frogs. We need to understand nature. And the frogs are there to teach us so much more about the environment, specifically because they are an indicator species. It is to our benefit to ensure the survival of our endemic biodiversity for the generations to come.”

 Too often amphibians are overlooked, receiving 75% less conservation funding than mammals, birds or reptiles, according to Jeanne Tarrant, who runs the threatened amphibian programme at the Endangered Wildlife Trust.

“The fact that almost half of amphibians are experiencing declines should be a massive wake-up call to humanity that all is not right with our planet — most people, however, are unaware that amphibians are even in trouble,” she says.