Family Pyxicephalidae

Strongylopus bonaespei (Dubois, 1980)

Banded Stream Frog, Cape Stream Frog, Mountain Frog, Long-toed Frog, Gebande Langtoonpadda (A)

By A.L. de Villiers and R.C. Boycott

Currently accepted name: Strongylopus bonaespei
Red listing status: Least Concern

Photo by Schuster Nikola, 2014. URL: FrogMAP: 2280

Distribution

S. bonaespei is endemic to the atlas region. Its distribution is restricted almost entirely to the mountain ranges of the Western Cape Province, extending marginally into the Eastern Cape Province. It is distributed from Hoogvertoon (3219AC) in the Cederberg in the north, to the southern foothills of the Soetanysberg (3419DD) in the south, and from the Cape Peninsula (3318CD, 3418AB, AD) in the west, to the Witelsbos Forest Reserve (3324CC) in the Tsitsikamma Mountains in the east.

Although S. bonaespei occurs mainly in mountainous areas, it has been found at a wide range of altitudes, from 10 m near the mouth of the Voëlgat River east of Hermanus, to 1670 m near Waaihoek Peak in the Hex River Mountains (Greig et al. 1979).

The atlas data are reliable and reasonably complete.

Habitat

S. bonaespei typically inhabits Mountain Fynbos but is sometimes found on the margins of forest. It seldom occurs on steep slopes or in deep kloofs, preferring flatter, more open situations near streams. Annual rainfall in these areas is >500 mm.

Breeding takes place in shallow, seasonal, marshy areas and seepages that are well vegetated, usually with long grasses, stands of restios and sometimes ferns.

Although this species has been recorded from remnants of natural fynbos vegetation in a pine plantation (Greig et al. 1979), it occurs mainly in natural fynbos habitats and appears to be intolerant of disturbance.

Life history

S. bonaespei breeds mainly in winter but also calls in spring and late summer if conditions are suitable. In the southwestern Western Cape Province, breeding mostly takes place from May to early August. However, calling activity has been recorded up to mid-September, and intense calling has been heard as early as February (A.L. de V. pers. obs.).

Although dense breeding choruses have been heard in ideal conditions, especially early in the breeding season, the calls are usually scattered with calling males well spaced from one another. During a 45-minute period in the late afternoon, 20 active S. bonaespei adults were captured in a 70×35 m area of seepage (Greig et al. 1979). Males have been found calling from ground level at the base of overhanging vegetation near the water’s edge, and from 10–20 cm above ground level, spread-eagled between tall grass stems (Greig et al. 1979). Although these calling positions were noted at night, calling activity appears to be mainly diurnal. Observations at one site indicate peak calling activity around sunset with only occasional calls heard during the night (Cunningham and Henderson 2000).

The eggs are laid out of water on waterlogged earth or moss at the base of, for example, a restio or grass tussock, within about 5–20 cm of temporary pools or shallow runnels of water in seepage areas. The eggs are laid singly and may either be scattered, grouped in clusters, or deposited in rows of up to six or seven eggs. The clutch size is 39–104 eggs (Greig et al. 1979; Cunningham and Henderson 2000; A.L. de V. pers. obs.). Each egg is encased in a jelly capsule c.7 mm in diameter. The eggs develop into benthic tadpoles that complete their metamorphosis in water.

Conservation

S. bonaespei is not threatened. It is relatively widely distributed and most of its habitat occurs in protected areas. These include the Cederberg, Grootwinterhoek, Boosmansbos wilderness areas, Limietberg, Hottentots Holland, Kogelberg, Grootvadersbosch, Maanschynkop, De Hoop, Outeniqua nature reserves, Tsitsikamma Forest, Agulhas and Cape Peninsula national parks, and others.

Threats to individual populations include invasive alien vegetation, tree plantations, wildflower farming, alteration of drainage patterns, too-frequent fires, building developments such as roads and dams, and urban encroachment in certain coastal areas. The most extensive of these threats is probably the spread of invasive alien vegetation that eliminates fynbos vegetation and reduces water resources. The control of invasive alien vegetation is the responsibility of the nature conservation authorities for the respective protected areas.

Current distribution map

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