The Red-flanked duiker is one of the smallest species of antelope. They have russet coats, with greyish-black legs and backs, and white underbellies. There are small white markings on the ears and snout and a dark streak runs along the center of the face. A tuft of black hairs grows between the horns and further coarse dark hairs grow along the top of the neck. Their legs are bluish-grey. The sexes are in general similar in appearance but males have short backward-pointing horns. Females are often hornless or may have shorter horns. Both males and females have large preorbital glands on their snout in front of their eyes which form bulges in their cheeks.
Red-flanked duikers are native to West and Central Africa where their range extends from Senegal and the Gambia in the west to Sudan and the Nile Valley in the east. Their main habitat is open savannah woodlands and the margins of forests but they also occur in river basins with elephant grass or thick shrubby vegetation such as caperbushes and tree acanthus.
Red-flanked duikers are territorial and mainly solitary animals. A single antelope or a pair usually occupy a small territory for a few months and then move elsewhere. This territory is marked with secretions from their preorbital glands. Red-flanked duikers are most active in the early morning and shortly before dusk. They move about while browsing and keep a sharp lookout for possible predators; if startled, they lower their heads and dive into the nearest dense area of vegetation. These animals have sharp senses of hearing and smell. In order to communicate with their young or when threatened they produce a shrill bark.
Little information is known about the mating system in Red-flanked duikers. The gestation period lasts around 8 months, with a single calf being born in the dry season or near the start of the wet season. The newborn weighs about 1 kg (2.2 lb). Right after birth the calf quickly makes its way into concealing vegetation, only coming out when its mother returns to nurse it. Immediately after birth and when grooming its calf, the mother marks it with the secretions from her preorbital glands. The calf is weaned when it weighs about 9 kg (20 lb) and there is no further parental involvement. Both male and female Red-flanked duikers become reproductively mature at about 9 months of age.
Red-flanked duikers are threatened by severe hunting pressure. Although these animals are very adaptable, the loss of the habitat due to logging may pose another threat in the future.
According to the IUCN Red List, the total population size of Red-flanked duikers is 170,000 individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List but its numbers today are decreasing.
As Red-flanked duiker eat the fruits, they swallow the seeds. These pass through the gut and are present in the droppings; this way these animals act as important seed dispersal in their ecosystem.