Hard times for South Africa's frogs

Almost a fifth of frog species in South Africa are under threat of extinction, a nine-year research project has found.

The Atlas and Red Data Book of the Frogs of South Africa, Lesotho and Swaziland (released on Thursday) was compiled by 400 contributors from 42 500 distribution records for the 114 recorded species of frogs in the region.

The book was officially launched at the University of Cape Town’s avian demography unit.

The atlas has found that 20 of the 114 recorded species of frogs (about 17%) are threatened. Four of these species are classified as critically endangered, eight endangered and eight vulnerable.

A further five species are near threatened, and the status of another eight is “data deficient” because so little is known about them.

Two of the four critically endangered species are found on the Cape Peninsula. These are the Table Mountain ghost frog, found in only four streams on Table Mountain, and the micro frog, whose only remaining population on the Cape Flats is in the indigenous vegetation inside Kenilworth racecourse.

The other two critically endangered frogs are Hewitt’s ghost frog, which occurs only in the Elandsberg in the Eastern Cape, and the mistbelt moss frog, which is restricted to the eastern escarpment of KwaZulu-Natal and the Eastern Cape.
Both species have their habitats threatened by commercial forestry and invasive alien vegetation.

Also of concern is the endangered western leopard toad, with breeding grounds at Zandvlei in the path of the proposed R300 toll road; and the endangered Cape platanna, now restricted to the Cape of Good Hope Nature Reserve, Betty’s Bay/Kleinmond and the Agulhas National Park.

Among the general threats faced by frog species are:

  • Afforestation (the planting of trees for forestry purposes) that dries up streams, seeps and wetlands and destroys indigenous vegetation;
  • Agriculture, particularly where too little natural habitat is left around wetlands;
  • Urban development, particularly in coastal areas; and
  • Road building, which often follows the paths of wetlands. The western leopard toad population, for instance, was originally decimated by the building of the Blue Route highway, which was constructed on its prime breeding ground.

The editors of the atlas note: “These statistics point emphatically and urgently to the need to include amphibians in conservation planning for the region ... While frogs figure large in folklore and scientific studies, they fare badly in conservation terms. Yet they are a critical part of the food web, both as predators and as prey, and serve as sensitive indicators of environmental health.”

The atlas is the result of a collaboration between herpetologists from the avian demography unit at the University of Cape Town, the school of health sciences at the University of the North, and several other universities, museums and conservation agencies around the country.

It is a joint publication of the Washington-based Smithsonian Institution and the ADU.—Sapa

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