Head and body length: 115-145 cm

Shoulder height: 70-80 cm

Tail length: 11-18 cm

Adult weight: 45-80 kg

The largest duiker species, with a stout form, barrel-shaped body, and hunched back. The coat is a uniform deep blackish-brown, and has a glossy, slightly oily texture. The yellow-backed duiker gets its name from a triangular patch of erectile yellow hairs on its back. This wedge begins as a narrow line along the spine in the middle of the back and widens towards the rump. The pale hairs which form this patch are up to 6.5 cm long, more than twice the length of adjacent dark hairs. The tail is thin and has a black tuft of hair at the tip. While the forehead is colored as the body, the muzzle, cheeks, and lower face are pale grayish-brown. A conspicuous slit in front of each eye marks the opening of the preorbital glands. On top of the forehead is a crest of long rufous hair. Both sexes have smooth, slender horns which extend backward in line with the forehead and have a slightly downward curve. Horns of females (9-13 cm long) are only slightly shorter than those of males (typically 13 cm long, up to 20.5 cm).

Similar species

• Jentink's duiker (Cephalophus jentinki) and Abbott's duiker (Cephalophus spadix) are both of similar size to the yellow-backed duiker. Both have very restricted distributions, and as adults neither has a characteristic yellow back. However, juveniles of all three species are very similar.

Gestation period: Likely ~230 days, but reports show a wide variation (151-282 days).

Litter size: One.

Weaning: By 5 months.

Sexual maturity: Unknown.

Life span: Up to 22 years in human care.

Breeding in the yellow-backed duiker does not appear to show seasonality. Infants are a uniform blackish-brown color at birth; the characteristic yellow triangle on the lower back begins to appear at 30-40 days of age as a pale stripe. This gradually expands and widens posteriorly until it reaches its full extent at 7-10 months of age.

Yellow-backed duikers may be active both day and night, with some reports indicating peaks of activity around dawn and dusk. Midday may be spent sleeping; favored resting spots include between buttress roots, in thickets, or near fallen trees. Although most observations are of solitary animals, anecdotal evidence suggests that pairs (one male, one female) may cohabit a shared home range. Both males and females use their preorbital glands to mark objects, although it is unknown whether this implies territoriality. Population densities appear to be relatively low, with 0.5-2.1 individuals per km² recorded in Gabon and in the Democratic Republic of Congo's Ituri Forest. When startled, this duiker will often freeze in position with one foreleg raised; simultaneously, the hairs of the yellow dorsal patch are erected, making the yellow back more conspicuous. After a brief pause, they flee with explosive speed into dense cover. The yellow-backed duiker is able to swallow whole fruits as large as 4.7 cm in diameter; large seeds are spat out while ruminating, and in doing so this species acts as a disperser for many tree species.

Family group: Solitary.

Diet: Primarily fruit, seed pods, and seeds. Also leaves, stems, and some animal matter (including ants, lizards and birds).

Main Predators: Leopard.

The yellow-backed duiker has the largest range of any forest duiker, occuring throughout the forest blocks of West and Central Africa. It is primarily found in secondary forest and edge habitats, such as riverrine forests and woodland patches interspersed with savanna. However, the species may occasionally be observed in a range of other habitats including swamp habitat and primary forest. The approximate range is depicted in the map below.

IUCN Red List: Near Threatened (2016).

CITES Listing: Appendix II (2017).

Threats: Uncontrolled hunting, habitat loss.

Based on population density estimates, the total population was calculated to be 160,000 individuals in 1999. The yellow-backed duiker is widespread, and has historically been protected from hunting in parts of its range by traditional taboos against eating its meat. However, observed declines in populations are expected to continue as traditions wane and human encroachment on forest habitats increases.