Family Pyxicephalidae

Afrana angolensis (Bocage, 1866)

Common River Frog, Angola River Frog, Common Rana,
Gewone Rivierpadda (A)

By A. Channing

Currently accepted name: Amietia delalandii (Boulenger, 1895 "1894")
Red listing status: Least Concern (2017)

Photo by Hankey Andrew, 2011. URL: FrogMAP: 125

Distribution

This widespread species is distributed from Ethiopia, south through East Africa to southern Africa, and westward to Angola (Poynton 1964). It occurs mainly in the eastern half of the atlas region, from just within the eastern border of Western Cape Province, northward at all altitudes up to 2000 m. A. angolensis has been recorded from the Vaal and Gariep (Orange) river drainages westward to the coast, and at a few scattered localities in the interior of Northern Cape Province. However, records from Lesotho should be treated with circumspection because of the difficulties in distinguishing the species from A. dracomontana.

The distribution data are comprehensive, but care needs to be taken in areas where this species may be confused with A. fuscigula or A. dracomontana. These two species share a number of colour patterns, and smaller individuals of A. fuscigula may be confused with larger individuals of A. angolensis.

Habitat

A. angolensis inhabits the Grassland and Savanna biomes, and forest fringe. Annual rainfall in these areas is 500–900 mm. The species tolerates some habitat disturbance and is frequently associated with human habitation, taking up residence in ditches and ponds, often where reeds and water lilies are present.

Breeding takes place in shallow water along the edges of pools, dams, streams and slow-flowing rivers. These frogs breed in both standing water in flat areas and running water traversing slopes of more than 14 degrees (Channing 1979). The same habitat is used throughout the year.

Life history

The adults spend the day floating amongst vegetation or basking on rocks above the water. Larger individuals may be found on banks or in vegetation above the water, leaping to the safety of the nearest pool when disturbed. This species has long hind legs and a fair amount of webbing between the toes, and is well adapted to jumping and swimming.

A. angolensis is active throughout the year and breeding has been recorded in all months of the year (Channing 1979). Males typically call from floating vegetation or from shallow water at the edge. Clutches of 400–500 eggs are laid in shallow, standing water. Tadpoles may grow to 80 mm in length (Wager 1986).

Being a common species that is active all year round, these frogs consume large numbers of flying and crawling insects. In turn, they constitute an important prey item for otters (Rowe-Rowe 1977a, b), large birds and snakes.

Conservation

This widespread species is found in all rivers, ponds, farm dams and other wetlands within its range. It is found in many protected areas. Localized threats include acid pollution from old gold-mine dumps. A. angolensis is not generally threatened.

Current distribution map

Undated records;  pre-1996;  1996 to 2002;  2003 to present