Zebra Duiker

Zebra Duiker Distribution

Literature available on the ecology of the species is very scarce. Except for the behavioural study in captivity conducted by Schweers (1984), no specific studies on this species have been carried out. General information on its ecology and an updated distribution map can be found in Kingdon (1997).

The zebra duiker is restricted to west Ivory Coast , Liberia and Sierra Leone (Wilson & Reeder, 1993; Wilson & Wilson, 1990). Its distribution map was obtained by including the whole of Liberia , the Ivory Coast country map in East (1990) and the Gola Forest area in Sierra Leone (Davies, 1987). Dr. R. East revised the preliminary map ( 23 June '97 )

Categorical-discrete (CD) distribution model

This species inhabits closed canopy primary forests, but is also found along forest margins and clearings, extending into secondary growth (Kingdon, 1997; Newing, 2001). Lowland forests (especially in river valleys) are preferred, but montane and upland forests are also colonized (Kingdon, 1997).

The zebra duiker has one of the most distinctive coats of any mammal and cannot easily be confused with any other species. An array of 12-15 black stripes cross the back and travel vertically down the sides, located from behind the shoulders all the way down to the root of the tail (Wilson, 1987; Walther, 1990; Kingdon, 1997). These transverse bands are wide at the spine and taper as they round over the flanks such that their tips form a lateral line between the limbs (Kingdon, 1997). As with their namesake, the zebras, the striping pattern is unique to each zebra duiker. In between these bold black markings, the coat is light gold, cream, or reddish-brown in color (Schweers, 1984; Kingdon, 1997). The undersides, including the belly, chest, and throat, are light yellow to nearly white and lack stripes, while the head, shoulders, and lower legs are a deep russet (Happold, 1973; Schweers, 1984; Kingdon, 1997). Dark garter-like markings ornament the upper legs, and in the hind legs, these bands cover a tufted gland just distal to the hocks (Kingdon, 1997). The tail is the same rufous as the rump, but has white hairs on the underside (Happold, 1973).

The face is a deep chestnut brown color, and the muzzle is black (Kingdon, 1997). While the jowls may be slightly lighter than the face, the zebra duiker lacks distinctive facial markings. The forehead lacks the tuft typical of most duikers, but, along with the nasal areas of the skull, the forehead is heavily reinforced with thick bone (Happold, 1973; Walther, 1990; Kingdon, 1997). Both sexes grow horns, which are robust, conical, and sharply pointed (Kingdon, 1997). Like most duikers, the horns are rather short, growing 4-5 cm long in males and no more than 2-2.5 cm in females (Walther, 1990).

The zebra duiker feeds on on leaves and fruits, and does not appear to be specialized into a specific dietary niche (Kingdon, 1997). Kingdon (1997) suggests that C. zebra may use its forehead to crack open larger thick-shelled fruits (Kingdon, 1997). Details on the diet of this species are unknown. Newing (2001) reports that zebra duikers will occasionally raid farmlands adjacent to forest to feed on crops. Individuals in the Frankfurt Zoo ate dead mice which were provided, sometimes after an extended period of play in which the mouse was shaken and tossed into the air (Schweers, 1984). Captive individuals have shown an apparent increased requirement for dietary copper as compared to conspecifics (Farst et al., 1980).

The following account on the breeding behavior of C. zebra is summarized from the detailed study conducted by Schweers (1984) on captive individuals in the Frankfurt Zoo. Males determine the reproductive status of females by smelling urine with a characteristic flehmen response, whereby the upper lip is curled upwards and the mouth is opened. In the days leading up to sexual receptivity, a male may apply secretions from his antorbital glands to the carpal and tarsal joints, head, neck, and back of the female, a behavior also noted by Udell (1981). Although the pair of zebra duikers observed by Schweers mutually marked each other outside of the female's estrus period, the frequency of this behavior was much more noticeable in the male duiker as the female approached estrus. In the wild, this may signal to other males that the female in question is being courted by another male.

Courtship in this species is relatively simple, with the male pursuing the female. This driving behavior may occur even when the female is not receptive. As the female approaches estrus, the pace with which the male follows after the female increases, and is accompanied by the male licking the neck, hind legs, and anogenital region of the female. Females respond to such attention by grunting loudly, turning the head to the side and stretching the lips to the side such that the bright lower surface of the chin becomes visible. While being driven by the male, a female will keep her head low and stretched forward, with the ears folded back. The male usually runs directly behind the female, stretching his head forward such that his neck is horizontal and the head is held at height the female's tarsal gland, a posture also reported by Udell (1981) for this species. The pursuit is performed with increasing frequency and urgency as the female approaches estrus. In addition to this, as females become more receptive they reduce the lateral swishing of the tail during pursuit and begin to hold it away from the body.

Mounting attempts occur when the female stops during pursuit. Mounting, preceded by the male smelling and licking the female's anogenital region, is initiated by the male pushing his chin onto the croup of the female. Copulation attempts are brief, lasting only a few seconds, but are repeated frequently (see Udell, 1981). Initial mounting attempts may occur during pursuit, with the female speeding up her pace to prevent successful intromission. As the female becomes receptive, her pace during pursuit slows and the number of stops increases, allowing the male increased opportunity to mount. While following the female, the male (and sometimes the female) makes throaty grunting sounds (also reported by Udell, 1981). Successful breeding was not observed by Schweers (1984), who suggests that this likely occurred at night.

Schweers (1984) recorded two ritualized behaviors performed by the male towards a receptive female. The first was a frequent high lifting of the foreleg, which occurred briefly before each mounting attempt. In this posture, the front leg was aimed past the hind legs of the female, rather than in between the legs as with the laufschlag of the gazelles. The second behavior similarly involved lifting a front leg up, but in this position the leg was held against the body of the female for an extended period of time. This was never followed by copulatory advances, but usually lead to the male tapping the female with his lips in order to reinstitute the pursuit.

IUCN threat category

The IUCN has classified the zebra duiker as a vulnerable species (Criteria A1c + C1) (Hilton-Taylor, 2000). The zebra duiker is on CITES Appendix II (CITES, 2003). The total population is estimated at 28,000 individuals, spread across 30,000 km² (East, 1999). This species is threatened by poaching for meat and the continued destruction of West Africa's remaining primary rainforests (East, 1999). The long-term survival of the C. zebra is dependent on protected areas to safeguard against habitat loss and control of hunting (East, 1999).