Family Brevicipitidae

Breviceps bagginsi Minter, 2003

Bilbo’s Rain Frog, Bilbo se Blaasoppadda (A)

By L.R. Minter

Currently accepted name: Breviceps bagginsi
Red listing status: Data Deficient

RED LIST SPECIES

Status: Data Deficient (DD)

Identification

B. bagginsi is a relatively small species: males are 20–25.9 mm (N = 19) in body length, and the single paratype female measured 28.7 mm. The call is a sharp, high-pitched trill of moderate length (emphasized frequency 2540–3042 Hz; duration 103–388 ms; N = 15). Each bout of calling consists of 7–19 closely spaced calls (Minter 2003).

The call of B. bagginsi is easily distinguished from the long, high-pitched whistle of B. sopranus, the very short, high-pitched chirp of B. mossambicus and the lower-pitched calls of B. adspersus which tend to be emitted in groups within the call bout (Minter 1995, 1997, 2003).

B. verrucosus, which also occurs in the Boston area, is larger than B. bagginsi and has a granular skin with two or more longitudinal, glandular ridges on the dorsum. The call of B. verrucosus is lower in pitch and longer than that of B. bagginsi (emphasized frequency 1550–2238 Hz; duration 421–912 ms; n = 34; Minter 2003).

Other Breviceps species that may occur in sympatry with B. bagginsi are B. sopranus, B. adspersus and B. mossambicus. Colour and markings are highly variable in these species and cannot be used to distinguish them from one another or from B. bagginsi. Identification should be based on their characteristic advertisement calls.

Distribution

B. bagginsi is endemic to KwaZulu-Natal and is recorded from only four quarter-degree grid cells: three between Babanango, Melmoth and Ulundi (2831AD, CA, CB), and one between Boston and Howick (2930CA). The atlas data are accurate but incomplete. A more intensive survey of suitable habitats may reveal additional populations.

Habitat

B. bagginsi inhabits the grassy verges of roads in heavily afforested areas at altitudes of 900–1400 m. The vegetation at these localities, prior to afforestation, probably comprised Short Mistbelt Grassland or Moist Upland Grassland. At present, no populations are known from undisturbed habitat.

Life history

Very little is known of the life history of this species. Breeding takes place in spring and early summer. Males call from the surface or from shallow depressions concealed beneath vegetation. In wet weather, calling continues throughout the day and males will continue to call from well-concealed sites in full sunlight at ambient temperatures as high as 28°C. Amplexus and oviposition have not been observed.

During the emergence of termite alates, individuals leave their places of concealment to feed in the open.

Conservation

Status

B. bagginsi is a recently described species (Minter 2003). It is assigned to the Data Deficient category (this publication). The species is not known to occur in any protected area.

Threats

Habitat loss due to afforestation obviously represents a serious threat to this species as it is known only from narrow, grassy roadside verges in areas where natural grassland has been replaced by plantations of eucalypts and pines. The fire regimes to which these grassy strips are subjected, as part of the management of the plantations, may in the medium to long term affect the viability of these frog populations. Road kills also constitute a serious threat, as all the known breeding sites lie alongside roads. The frogs cross the roads during the breeding season and are especially vulnerable when they swarm onto the roads during the emergence of alate termites.

Recommended conservation actions

Distribution, life history and ecological data are urgently needed to assess the conservation status of B. bagginsi and develop an appropriate conservation plan.

Current distribution map

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