Cephalophus callipygus [Peters, 1876].

Citation: Monatsb. K. Preuss. Akad. Wiss. Berlin, 1876:483.

Type locality: Gabon, Gabon River.

The taxonomic record (above) is taken from Wilson and Reeder (1993). The taxonomy of the red duikers is quite convoluted. Earlier authors considered this species as a form of C. natalensis (see Wilson, 1987). It is now thought to be part of a species complex, with a progression from C. callipygus in the west through C. weynsi and C. harveyi, to C. natalensis in southern Africa; many of these forms have been treated as subspecies of Peters's duiker, particularly C. weynsi (Walther, 1990; East, 1999; Wilson, 2005). Peters's duiker, as recognized here, is monotypic with no synonyms (Wilson, 1987; Wilson and Reeder, 1993).

Cephalophus callipygus is a relatively large duiker, with a body weight averaging 20.1 kg (Dubost, 1984; Kingdon, 1997). Head and body length is 80-115 cm, and shoulder height is between 45 and 60 cm (Walther, 1990; Kingdon, 1997).

The general coloration of Peters's duiker is a reddish brown, typically paler on the neck and forequarters and darker towards the back and rump (Wilson, 2001). There is considerable variation between individuals from pale and tawny to a rich russet or even dark brown (Happold, 1973; Kingdon, 1997). A fine black dorsal line begins between shoulders and runs along the spine to the rump, where it expands over the rear flanks, including the tail (Happold, 1973; WIlson, 2001). The noticeably darker hindquarters are one of the defining characteristics of this species (Walther, 1990). The legs, shoulders, neck, and face of some individuals are also dark (Kingdon, 1997). The underparts are paler than the rest of the body, but not whitish (Happold, 1973; Wilson, 2001).

The head is not distinctly marked, but a rich russet or orange brown tuft of hair is present on the forehead (Happold, 1973; Kingdon, 1997; Wilson, 2001). Two pale spots approximately 1 cm in diameter are found below and behind the eyes (Wilson, 2001). Both sexes have horns, which are short, pointed, and in line with the face (Walther, 1990). In males, the horns average 8-10 cm (6.2 cm up to 14 cm), while 4.0-5.8 cm is typical for females (Walther, 1990; Wilson, 2001). The skull of C. callipygus shows a strongly reinforced forehead, with the frontal bone up to 18 mm thick (Kingdon, 1997; Wilson, 2001).

Peters's duiker breeds continuously throughout the year (Feer, 1989; Dubost and Feer, 1992). Dubost and Feer (1992) noted two peaks in births in Gabon - one in May/June and another in December. These birthing peaks occur in the early months of the two dry seasons, when the quantity and quality (protein content) of fruits eaten by this species are at their highest. The same authors estimated the gestation period for C. callipygus to be approximately 240 days, similar to the bay duiker (C. dorsalis). A neonate examined by Wilson (2001) weighed 3.0 kg (two full-term fetuses similarly weighed 2.7 and 2.9 kg). Infants are dark brown overall (darker than adults) and possess the characteristic dark dorsal stripe; the head and neck are paler than the body, and the forehead crest is bright red (Wilson, 2001).

C. callipygus inhabits moist equatorial forests. Lowland forest is the most frequented habitat, but thickets are also used (Wilson, 1987; Kingdon, 1997). Peters's duiker relies on dense undergrowth for shelter; it may be found in both primary and secondary forests, but avoids outlying riverine strips and gallery forests (Kingdon, 1997). Due to its preference for low vegetation, this species does well in forests which are regenerating after logging (Kingdon, 1997; Wilson 2001).

Peters's duiker is strictly diurnal (Feer, 1989; Kingdon, 1997). It is often encountered foraging on fallen fruits and leaves in areas without undergrowth, but flees into dense cover if threatened (Wilson, 2001). Nighttime resting spots tend to be situated in more open areas instead of thickets (Wilson, 2001).

Observations of Peters's duikers are typically of solitary individuals, but (unusual for duikers) there is an active social system and polygynous social structure for individuals inhabiting the same area (Feer, 1989). Adult females occupy home ranges of approximately 40 hectares in size (Feer, 1989), which presumably overlap with those of several other females. Males are believed to be territorial (Kingdon, 1997), although no estimate of their home range size has been made. C. callipygus is able to live at high population densities (Feer, 1989). Density estimates from line transects in the Central African Republic were 0.9 animals per km², while net encounters indicated population densities of 0.9-4.4 animals per km² (Noss, 1998). Other authors have reported densities as low as 0.6 per km² to as high as 15.5 per km² (see Noss, 1998).

This species forages primarily in mature forest and is one of the most completely frugivorous duiker species (Dubost, 1984; Kingdon, 1997). In two different studies (Dubost, 1984; Feer, 1989), fruit was found to comprise between 82.7% and 89.6% of the diet by dry weight based on examination of stomach contents. Leaves are the next largest dietary component, comprising 7.9-10.0% of the diet, with petioles and stems following close behind at 6.2%. Fruits and leaves were found in the stomachs of all Peters's duikers sampled in both studies. Flowers, fungi, and animal matter (principally insects) are found much less frequently (in fewer than 50% of animals sampled), and comprise less than 1% of the diet. A Peters's duiker observed by Wilson (2001) in the Central African Republic actively (and successfully) hunted infant Hartlaub's ducks (Pteronetta hartlaubii). Unweaned animals eat much less fruit than adults (52.7% of diet by dry weight), and significantly more leaves (37.0%), but similar amounts of stems (9.8%) and fungi (0.47) (Dubost, 1984).

The proportions of food items changes seasonally; a significant increase in the amount of leaves consumed (and decrease in fruits eaten) occurs during the short rainy season, from March to May (Feer, 1989). This species is not specialized in respect to the species of fruits eaten, but is adapted to feeding on a specific size of fruit: 40.2 % of fruits consumed are 1.0 to 2.0 cm in diameter, and 77.2% of fruits are between 0.5 cm and 3.0 cm (Dubost, 1984). Dubost (1984) identified 55 fruit species in 20 stomachs analysed, and Feer (1989) found an average of 8.5 species in each stomach (n=51). The favored species of fruit, as determined by Dubost (1984), are Xylopia hypolampra (Annonaceae), Cylindropsis parvifolia (Apocynaceae), Canarium schweinfurthii (Burseraceae), Klaindedoxa gabonensis (Irvingiaceae), Coelocaryon preussii or Pycnanthus angolensis (Myristicaceae), and Staudtia stipitata (Myristicaceae).

C. callipygus inhabits the central African rainforest block between the Atlantic Ocean and the Congo and Ubangi Rivers (Wilson and Reeder, 1993; Wilson 2001). Although some museum specimens were collected north of the Sanaga River, Peters's duiker is predominantly found south of this body of water (Wilson, 2001).

Countries: Cameroon, Central African Republic, Congo, Equatorial Guinea, Gabon (East, 1999).

Peters's duiker is classified as a species of least concern by the IUCN (2011), and is not listed by CITES. The total population in 1999 was estimated at 382,000 (East, 1999). The primary threats to the survival of this species are habitat loss due to human settlement and hunting (IUCN, 2011). Peters's duiker is especially affected by snare hunting; in the Central African Republic this species accounted for 29% of all animal captured in snares (36 out of 105) and 56% of captures by weight - indeed, hunters in the Central African Republic equate their total returns in C. callipygus units (Noss, 1998). Snare hunting does not appear to be sustainable for this species, even under the most optimistic of circumstances, and unless mediatory actions are taken, this species could decline drastically (Noss, 1998).

The genus Cephalophus is derived from kephale (Greek), the head, and lophus (Greek), a crest, referring to the prominent tuft of hair on the forehead of this, and most other, duiker species. The species name callipygus is likely from kalos (Greek) meaning beautiful or fair and puge (Greek) the rump: the dark color of the rump is a defining characteristic of this species.

Local names

Mbindi [Mpongwe (Gabon)] (Wilson, 2001)

Zumbi [Sanga] (Wilson, 2001)

Momjombi [in Dzanga-Sangha, Central African Republic] (Wilson, 2001)

 

French

Céphalophe de Peters (Walther, 1990; Kingdon, 1997)

 

German

Schönsteiss-Rotducker (Happold, 1973)

Petersducker (Kingdon, 1997)