Bioacoustics of Cephalophus castaneus

Movements, Home range and Social organization. Almost exclusively solitary. Social contact may occur during periods of activity, but tends to be brief. Eastern Bay Duikers are never found resting with others. Individuals inhabit home ranges that may vary from 0-07 km?® to 0-79 km?; in a study in Gabon , females generally used 0-2-0-4 km? and the single male used an area twice that size. Overlap between home ranges may result in up to six or seven duikers (including infants and juveniles) being present in a single male’s range. Home ranges vary in size depending on season, being generally larger during the dry seasons. The sense of smell is most important for social communication. Males mark vertical objects (especially tree trunks) with secretions from their preorbital glands at a frequency of 19-20 markings/hour, forming a whitish plaque of crystallized secretion on often-used branches. Eastern Bay Duikers tend to move slowly with the head stretched out at shoulder height, dropping the head so that the nose is at ground level on a regular basis. Individuals will frequently stop to smell areas marked by other duikers with preorbital gland secretions, urine, or feces. Vocalizations are rare; a weak “hon,” produced with a closed mouth, is used when two individuals are in close proximity (either in sight or when scent marks are sufficiently fresh). Being nocturnal, the sense of sight is not especially important; visual signs (such as horn scrapes on tree trunks or bushes) are not left. Likewise, detection of danger is principally by smell and hearing. Upon detection, an Eastern Bay Duiker will freeze in position; the head (with ears pricked) is then moved either side-to-side or up-anddown to better detect the threat. A threatened duiker will attempt to move off silently if possible. When startled, this species will flee directly into dense cover with the head stretched forward, and will then observe the threat while standing stock-still. Thereis no alarm vocalization or warning in the form of stamping of the forefeet.