Family Brevicipitidae

Breviceps adspersus Peters, 1882

Bushveld Rain Frog, Common Rain Frog, Senanatswi (P), Bosveld Reënpadda (A), Gewone Blaasoppadda (A)

By L.R. Minter

Currently accepted name: Breviceps adspersus
Red listing status: Least Concern

Photo by Jessnitz V, 2012. URL: FrogMAP: 537

Distribution

Beyond the atlas region, B. adspersus occurs in Namibia, Botswana, Zimbabwe, southern Zambia, and Mozambique (Poynton and Broadley 1985a). In the atlas region, the subspecies B. a. adspersus occurs in its preferred habitat throughout most of Limpopo and North West provinces, the northern Free State, the eastern parts of Northern Cape, Gauteng, Mpumalanga, central and eastern Swaziland, and at lower elevations in KwaZulu-Natal, as far south as Margate (3030CD).

Call data and molecular evidence (Minter 1998; Engelbrecht and Mulder 2000) support the retention of the subspecies B. a. pentheri in the Eastern Cape, where it is distributed from Joubertina (3323DD) inland to Grahamstown (3326BC), and northward as far as the Stutterheim district (3227BC). Populations from the Great Escarpment of KwaZulu-Natal and Mpumalanga, e.g., near Wakkerstroom (2730AD), previously referred to B. a. pentheri by Poynton (1964), were assigned to B. mossambicus on the basis of advertisement call structure (Minter 1998).

Light paravertebral and dorsolateral patches on the dorsum of B. adspersus distinguish this species from northern Mozambique populations of B. mossambicus, which lack these markings (Poynton 1964; Poynton and Broadley 1985a; Lambiris 1989a; Minter 1998). However, this is not the case in the atlas region, where similar markings are present in B. sopranus, B. bagginsi and in populations of B. mossambicus from the Great Escarpment and coastal KwaZulu-Natal (see B. mossambicus species account).

A study of advertisement calls (Minter 1998) did not support the hypothesis that B. adspersus and B. mossambicus hybridize extensively in KwaZulu-Natal (Poynton 1964; Poynton and Broadley 1985a; Lambiris 1989a). The hybridization hypothesis was based on dorsal markings that do not constitute a reliable diagnostic character. Therefore, existing museum and literature records of B. adspersus from KwaZulu-Natal, unless based on advertisement calls, should be regarded as unreliable. A survey based on advertisement calls is needed in order to re-map the distribution of B. adspersus in the northeastern parts of the atlas region, and the atlas data from the pre-1996 period should be viewed with circumspection.

Habitat

B. a. adspersus inhabits semi-arid habitats with sandy to sandy-loam soils. Its distribution closely matches that of the Savanna Biome, particularly the bushveld vegetation types that are characterized by “a grassy ground layer and a distinct upper layer of woody plants” (Low and Rebelo 1996). It is conspicuously absent from the Grassland and Forest biomes.

B. a. pentheri occurs in Eastern Thorn Bushveld, Spekboom Succulent Thicket and Valley Thicket. In Polokwane and Grahamstown, parks and gardens with well-turned, sandy soil contain breeding populations of B. a. adspersus and B. a. pentheri respectively, indicating that this species can survive in a suburban environment.

Life history

The dry season (in this case, winter) is spent 15–30 cm below the surface, often in situations where soil moisture is conserved, for example, next to or under rocks, logs, stumps or tree roots (Jacobsen 1989; pers. obs.).

In spring or early summer, following heavy rain, males emerge from the soil and establish call sites 5–200 cm from their winter retreats. The call site usually consists of a well-concealed shallow depression, about the depth of the frog’s body, at the base of a grass tuft or small herbaceous plant. In overcast, damp conditions, calling may continue unchecked for several days and nights. Males are prompted to call by the calls of their immediate neighbours, and this results in bouts of calling which spread through the population in waves. When hot, dry weather returns, or when disturbed, males retreat to their underground burrows. Males were observed to use the same call site for up to five consecutive nights (Minter 1995, 1998).

Amplexus is facilitated by a sticky skin secretion which ensures that the male remains attached to the female during nest construction. A mass of about 45 eggs, covered by a smaller mass of fluid-filled jelly capsules lacking yolk, is deposited in a chamber about 30 cm below the surface. The female remains nearby until the froglets are ready to leave the nest (approximately six weeks). The reason for her presence has not been established (Minter 1995, 1998).

Conservation

The species does not appear to be at risk since much of its habitat is used for game and cattle farming and is relatively undisturbed. It also occurs in a number of provincial nature reserves and national parks.

Current distribution map

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