Discover Highway’s fantastical frogs

Tadpoles develop inside the jelly mass of eggs. PHOTO: Nick Evans

FROGS are at the forefront of environmentalist’s minds as they are a good proxy to indicate the health of an ecosystem.

Owing to the semi-aquatic life-cycle, and their semi-permeable skins, frogs are especially vulnerable to pollutants and other environmental stresses. Consequently, frogs can be regarded as useful environmental bio-monitors, and may serve as an early-warning alarm system indicating changes in the environment and potential threats to other organisms, including humans.

Amphibians are currently the most threatened class of vertebrate on earth, with 32 per cent of species red listed as critically endangered, endangered or vulnerable.

Twenty five of the 116 species of frog found in South Africa can be found in the Upper Highway. This places a special responsibility on all residents to protect all amphibians to make sure they are there for future generations. Some of the simple things residents can do to protect these species is to to stop destroying even small wetlands on their properties and to keep small streams free of invasive aliens and not dam streams. The use of harmful chemicals and pesticides should be avoided at all times.

One species that we should be particularly sensitive to is the Kloof Frog which is on the endangered list mainly because its traditional habitat has been destroyed by housing developments. As much as we would love to claim it as our very own, it is not named after the suburb of Kloof but after its habitat which consists of steep-sided, wooded ravines or valleys. On a positive note, searches in the Highway area in recent months by Dr Jeanne Tarrant of the Endangered Amphibian Programme and Nick Evans from KZN Amphibian and Reptile Conservation have discovered some new breeding sites for this species.

The Kloof Frog’s scientific name is Natalobatrachus bonebergi. It was described in 1912 and named for Father Bonebergi from the Marianhill Monastery who discovered the species in Mariannhill.

The Kloof Frog:

Females can grow up to 37mm and males up to 25mm in length.

The frog can live up to five years.

Conservation Status:

Endangered. In view of its area of occupancy of less than 500km2, its distribution is severely fragmented, and there is a continuing decline in the extent and quality of its habitat, area of occupancy and number of locations.

Description:

The back is light greenish-brown to grey, sometimes with pale spots and a pale vertebral line. A distinctive black stripe runs from eye through the lower part of the eye and down the arm. This band is bordered below by a narrow white band along the upper jaw. It has a pointed snout which protrudes over the lower jaw. Its underside is cream-coloured and its fingers and toes are long and end in large discs. The toes are slightly webbed.

Behaviour:

They are agile jumpers, strong swimmers and can escape easily and hide in rotting plant material at the bottom of pools. Expanded adhesive toe-tips (t-shaped) allow easy movement over vertical rockfaces and slippery surfaces.

Diet:

Insects (the tadpoles feed on algae).

Breeding:

From October to May. The male frog will one to two metres above the water in overhanging vegetation. He makes a faint clicking advertisement call. The female responds and clutches of 75 to 95 eggs are laid in clear masses which are attached to leaves, branches or rocks above water. The female keeps them moist with fluid from her cloaca. Tadpoles develop inside the jelly mass and 6 days later emerge and drop to the water below. Metamorphosis is complete within 60 days.

Distribution:

Restricted to rocky streams in coastal and gallery forests of of the northern Eastern Cape (from Dwesa Nature Reserve) and eastern KwaZulu-Natal. It occurs below 900m average sea level. It occurs in several protected areas, including Krantzkloof, Umtamvuna and Oribi Gorge Nature Reserves.

Habitat:

Rocky streams in coastal forests and gallery forests, and alternate between fast-flowing sections and larger tranquil pools with a gravel bed. It does not survive in open areas.

Threats:

Afforestation as a result of sugar plantations and housing developments have encroached on the specialised habitat of the species. It is also threatened by pollution and siltation of streams.

Hop along to talk:

Join the Kloof Conservancy for its annual frog evening on at the beautiful Tanglewood Farm on Saturday, 18 February from 4pm.

The back-to-nature frog evening will be hosted by amphibian expert, Dr Jeanne Tarrant. There will be educational activity tables and after sunset there will be a guided walk, so be sure to pack your gumboots, buckets and torches or headlamps.

Entry is R30 per person and R15 for children under 12 years old. All proceeds will go to the endangered amphibian programme.

Take along your own picnic baskets but there will be wors rolls and cold drinks on sale.

  AUTHOR
Lloyd Mackenzie
Journalist

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