Cape Grysbok

Raphicerus melanotis (Zimmerman, 1780)

Photo: Doug Lee

IUCN Conservation Status:

Lower Risk, conservation dependent (LR/cd)
A shy, solitary, nocturnal animal that is rarely seen. It is regarded as a problem animal in the Western Cape where they cause extensive damage to grape vines. Motorists travelling in the Grahamstown and Uitenhage areas of the Eastern Cape Province often see them roaming on the road reserves late in the afternoon or at night. There is little available scientific information about the grysbok.

Taxonomy

Classification 

The two species endemic to Africa are:

• the Cape grysbok Raphicerus melanotis
• the northern grysbok R. sharpei with the subspecies
• R. sharpei colonicus the Tropical grysbok
• R. sharpei sharpei Sharpe’s grysbok

Sharpe’s grysbok was named after Sir Arthur Sharpe who described the species from the first recorded specimen collected in Malawi.

Description

A small antelope that is tawny-brown on the back and flanks, with single white hairs scattered throughout the pelage giving it the white speckled appearance after which its named; the Dutch word “grys” meaning grey. The underside of the body is yellow-brown. The face, neck and upper legs are less speckled. The ears are large and are a distinctive whitish-grey on the inside. The northern grysbok is smaller than the Cape grysbok and has a lighter colour. Ewes are heavier than rams but have a lower shoulder height. When feeding, the profile of the hindquarters is higher than the shoulders. The distinguishable difference between the two grysbok species is the false hoof seen on the back of the legs above the hoof of the Cape grysbok. The northern grysbok lacks false hooves.

Comparison To Man

Trophy

Horns are carried by the ram alone and are straight, pointed and almost vertical with only the tips bending forward slightly. The horn length of an adult Cape grysbok varies from 4.5-10 cm with a mean of 7.1 cm.

Habitat requirement

Cape grysbok require a very specific habitat and have a fragmented distribution, associated with dense, short, shrubby thicket along low gradient, undulating hills and the slopes at the foot of mountains. Cape grysbok also occur in kloofs, broken landscapes, coastal forests and dry succulent environments with sufficient shrub for refuge and hiding. The main habitat distribution of the Cape grysbok, in descending order of ranking is: rhino-bushveld, fynbos, mixed Karooveld, succulent valley bushveld and succulent montane scrubveld. They are often seen on beaches in late afternoon. Cape grysbok are able to inhabit arid environments as they are independent of surface drinking water. The northern grysbok inhabits thicket vegetation, but of a different composition than that of the Cape grysbok. The preferred habitat consists of low shrubs and grasses of medium height (4050 cm) in broken, sub-tropical savannah woodland and sub-tropical bushveld, especially along water courses, drainage lines and rivers. Continuous stands of tall grass and shaded kloofs are avoided. Seepage lines at the base of rocky hills are favoured. A sufficient under-storey of shrubby vegetation is essential. Tropical grysbok also inhabit the arid, sweet, mopane veld of Colophospermum mopanae that has little grass and a dense under storey of shrubs. As northern grysbok drink daily they prefer habitats with water courses and seepage lines.

Distribution

Feeding & Nutrition

Grysbok are nocturnal and are active from one hour before sunset to one hour after sunrise. Most of the daylight hours are spent lying under thicket vegetation or in old aardvark burrows. Northern grysbok are also fond of lying between large rocks. Many books incorrectly describe the Cape grysbok as being a grazer. Scientific research has shown that grysbok are mixed, concentrate or highly selective, feeders consuming large quantities of browse and fruit and 9% grass. The major of the intake comes from a diet that consists of vegetation with a high moisture content, contributing to the Cape grysbok’s independency of drinking water. In contrast, northern grysbok are rarely found far from surface water as they need to drink daily. A study of the contents of 91 Tropical grysbok stomachs revealed a dietary consumption of 70% browse and fruit, and 30% grass.

Social structure

Grysbok are solitary and are only seen in pairs when a territorial ram temporarily accompanies a ewe for mating (1-3 days at a time) or when a ewe accompanies her young. After weaning the ewe drives the lamb away by biting its ears. Communal feeding grounds often include areas with a rich food supply such as orchards or vineyards. Several grysbok from surrounding home ranges may tolerate each others presence at these grounds and, at times, up to 4-5 grysbok may be seen in company although they still avoid physical contact and keep
several meters apart. A single ewe may bear up to nine lambs in six years. The lamb weighs 1.5 kg, and starts to feed on vegetation from an age of 2 weeks. It reaches an adult body size at 6-7 months.
Both adult rams and ewes have a permanent, fixed territory that is aggressively defended The territory forms the core of a larger, fixed home range that is required for a sufficient food supply. Adjacent home ranges generally overlap by <25%. The home range of an adult ram overlaps that of 2-4 adult ewes by as much as 30% and it is generally slightly larger than the home ranges of the ewes.

Information Table

Bibliography