Table Mountain ghost frog
Table Mountain ghost frog
The Table Mountain ghost frog, which reaches a body length of about 50-60 mm, is green with reddish-brown to purple mottling above and a pinkish-white underside. It has webbed toes, with sucker-like pads at the toe and finger tips, enabling it to climb slippery, vertical rock faces in fast-flowing streams. It is similar to other ghost frog species but differs in that it has a prominent thumb-like metacarpal tubercle on the inner finger, and no transverse band through the eye.
This species inhabits moist ravines, gorges and valleys in natural forest and fynbos. It breeds in the clean, clear water of mountain streams, and is dependent on perennially flowing streams since ghost frog tadpoles take more than a year to develop into frogs. The adult frogs occur in and around the streams on moss-covered rock faces and in crevices, but also inhabit damp, sheltered habitat away from the streams, including caves.
Little is known of this frog’s life history because it is an elusive frog that occurs in low numbers and is very rarely seen. Another reason for this is that at least 70% of this frog’s habitat includes steep, rugged, inaccessible terrain. The eggs and oviposition sites of this frog have not been found and only once has its advertisement call been recorded. The tadpoles have distinctive sucker-like mouth parts which enable them to cling to slippery surfaces in fast-flowing streams. They are, therefore, well adapted to survive in the streams for more than a year and endure the winter torrents. The tadpoles feed on algae covering stream substrates and their feeding trails are sometimes seen on rocks in quieter pools. Gravid females (containing eggs) have been recorded in October and December. The advertisement calls have been heard in December. This coincides with the slower flow and lower level of the streams during summer.
This species is endemic (restricted) to an area of less than 10 km² of Table Mountain, situated mainly on the southern and south-eastern slopes above Cape Town.
Although all its habitat is situated in a protected natural environment, this frog is threatened in places by:
- Erosion – caused by human pedestrian traffic (with exposed hiking trails in steep areas requiring special management), stands of alien vegetation, overgrazing and trampling by the invasive Himalayan Tahr, and too frequent fires. This leads to streams being clogged with sediment.
- Invasive alien vegetation – causes reduced runoff and stream flow, and erosion. Furthermore, alien deciduous trees alongside streams (e.g. poplars), lead to the severe clogging of tadpole habitat with leaf-litter.
- Water abstraction – is a threat in most of the streams inhabited by this species. This causes some sections of streams to dry up during summer and, consequently, the obvious loss of tadpole habitat.
Potential threats include:
- Climate change: warmer and drier climatic conditions may lead to the loss of perennial streams.
- Disease: in particular, the potential threat of the pathogenic amphibian chytrid fungus, Bactrachochytrium dendrobatidis, is being investigated. This fungus has led to amphibian losses elsewhere in the world.
All habitat of this species is protected by being situated within Table Mountain National Park and part of Kirstenbosch National Botanical Garden.
CapeNature monitors the conservation and management of this species, with monitoring being focused on tadpole populations and habitat threats.
Sound conservation management advice to the relevant authorities enables appropriate management. This includes erosion and alien vegetation control, and the regulation and maintenance of perennial stream flow from the various reservoirs on top of the mountain.
This species is protected by the Nature Conservation Ordinance of the Western Cape Province. For example, it is illegal to collect and translocate this species.