Diurnal and nocturnal strategies of the bushbuck Tragelaphus scriptus (Pallas)

Summary Bushbuck density, activity cycles, and ranging patterns on the Mweya Peninsula have been determined by continuous observation of individually recognizable animals. Individuals were followed for periods of 2 to 12 h, and observations were continued at night with the aid of a Starlight Scope image intensifier. The density of this population of bushbuck is very high compared to those reported using more standard censusing techniques. Home range size is larger (15‐3‐35‐2 ha) for adult and subadult males than for females and immatures. Sex ratios show a preponderance of adult females, as has been reported for other populations. Contrary to most published accounts, these bushbuck are no more active at night than during the day; rather, they exhibit cycles of activity with a periodicity of 2–5 h. A crepuscular peak of movement is, however, apparent. Examination of individual home ranges and of ranging patterns indicates that this crepuscular activity peak is connected with a complete disjunction of areas utilized at night and during the day. Bushbuck move out of thickets into patches of grassland at dusk, returning to thickets before dawn. Other differences between nocturnal and diurnal activity include an increase in the relative amount of grazing at night. Possible reasons for these phenomena, in particular the probable role of predation, are discussed.