Connochaetes gnou (Zimmermann, 1780)

Don E. Wilson & Russell A. Mittermeier, 2011, Bovidae, Handbook of the Mammals of the World – Volume 2 Hoofed Mammals, Barcelona: Lynx Edicions, pp. 444-779 : 663

162.

Black Wildebeest

Connochaetes gnou

French: Gnou a queue blanche / German: WeiRschwanzgnu / Spanish: NU negro

Other common names: White-tailed Gnu, Swartwildebees

Taxonomy. Antilope gnou Zimmermann, 1780 ,

Cape of Good Hope. Restricted by P. Grubb in 1999 to Agterbruintjieshoogte, Somerset East district.

This species is monotypic.

Distribution. South Africa, Lesotho, and Swaziland.

Descriptive notes. Head-body 170-220 cm, tail 80-100 cm, shoulder height 111-121 cm (males) and 106-116 cm (females); weight 126-161 kg (males) and 110-130 kg (females). The horn bases are expanded, flattened, and angled forward; the horns turn outward and then forward. The pelage is dark brown to black in winter, somewhat paler in summer; the tail is white. The mane, which stands erect, is long and bushy; its hairs are pale at base and black toward the tips. The beard is long and dark, and there is a mane from brisket nearly to belly. Old males become almost black. Juveniles have shaggy, fawn-colored coats; the horns rise straight up, and start to curve at nine months. The back slopes from the shoulders to the hindquarters. The midface, from the level of the eyes forward, has a brush of long hair that divides into two at nostril level. Diploid chromosome number is 58; the X-chromosome is large and acrocentric and the Y-chromosome is small and acrocentric. On the basis of mtDNA,a divergence date between the Black Wildebeest and the Blue Wildebeest ( C. taurinus ) of somewhat over one million years ago has been calculated, assuming a divergence rate of 2% per million years. Wildebeest are quite different in appearance and posture from other genera of the tribe; the head is large and held low, and the nose is convex, with a brush of short,stiff hair, and huge valvular nostrils. The horns are thickened and expanded at the base, and oriented either sideways or forward, curved downward and then up, not upright like other genera.

Habitat. The Black Wildebeest is at home in temperate grasslands.

Food and Feeding. Mostly a grazer, but does a lot of browsing during the cold months; one three-month study found 63% grass and 37% karroid shrubs in its diet. It has recently been claimed that the yearlong diet is as much as 90% grass, especially Sporobolus species, Themeda triandra, and Cynodon dactylon. Stable isotope analysis of dental enamel corroborates this and indicates a diet consisting of 94% grass.

Breeding. The onset of breeding seems to be influenced by shortening daylength; it mainly occurs in March-April, but continues until July. A cow solicits a bull with tailswishing across his face; the tail is held up during mating. Gestation is 8-5 months. Calving occurs in November—January. The female remains with the herd for calving; just before the birth, she starts to become restless, repeatedly lying down and getting up. Calves can stand after nine minutes, and mothers and their young calves form a kind of creche. Calves start to graze at one month, but are not fully weaned until 6-9 months; they stay with their mothers until the next calf is born, or until a bull drives them away. Males mature in three years, and first try to become territorial at four. Most females conceive first at 16 months.

Activity patterns. In summer, the Black Wildebeestis active in early morning and late afternoon, and even before dawn and after sunset. In winter, it may be active for most of the day. When disturbed, members of the herd start bucking, head-tossing, and snorting, then gallop off, and suddenly whirl around, seemingly to investigate the cause of the disturbance.

Movements, Home range and Social organization. Female herds average 11-32 in most populations, and are larger in high-density populations. The herds have a hierarchy, which is maintained by head-nodding and head-shaking. Home ranges average 100 ha in the well-provided Willem Pretorius Game Reserve, but are larger where the range is poorer. Male territories are large, the males being spaced apart by 180 m up to 1 km, but are clustered across the landscape. Mostterritories are occupied year-round. The territorial call is a kind of hiccup, the male jerking his head up with each hic. The territorial males challenge each other with tail-swishing and head-shaking, and chase females and young while performing the nodding display, a movement that probably indicates intent to stab. Bachelor herds, whose members are unaggressive toward each other, sometimes join the female herds when there is less territoriality among solitary males. Territories are marked with feces (defecation is preceded by pawing, urinating, preorbital gland and hoof-gland marking, by vocalising (“ge-nu”) and by a conspicuous stance (static-optical marking). Territorial males canter stiff-legged and gallop with their heads moving up and down,tails lashing, sometimes kicking out with their hindlegs. Males in general threaten other males by kneeling, horning the ground, and sometimes rolling, along with vocalizations and marking. Female herds wander over the territories; during the rut, the territorial males herd them tightly, and the bachelor males try to harass them.

Status and Conservation. Classified as Least Concern on The IUCN Red List. Formerly found throughout the Highveld, moving on to the Karroo during the rains, as far north as North West Province and south-east to KwaZulu-Natal, South Africa. The species was widely shot out during the 19" century, and its numbers reduced to about 600 or less; it became protected on two farms in the Free State, South Africa, and recovered well. By 1996, the number had increased to over 10,600. Currently the population is scattered on numerous small private farms.

Bibliography. Estes (1991a, 1991b), Skinner & Chimimba (2005).

Figures

162. Black Wildebeest (Connochaetes gnou), 163. Blue Wildebeest (Connochaetes taurinus), 164. Johnston’s Wildebeest (Connochaetes johnstoni), 165. Eastern White-bearded Wildebeest (Connochaetes albojubatus), 166. Serengeti White-bearded Wildebeest (Connochaetes mearnsi)

Distribution. South Africa , Lesotho , and Swaziland .