Blue duikers are most active at dawn and dusk (5) (10) (11) and feed mainly on fruit, as well as leaves, flowers, fungi, seeds and sometimes insects or even small animals (4) (5) (8). Like other duikers, they may follow feeding monkeys and birds through the forest, picking up the fruits that are dropped (2) (6). The blue duiker is monogamous, with pairs appearing to mate for life and living in a small territory, which is defended against other blue duikers and regularly scent-marked (2) (5) (6). Breeding occurs year-round (4) (10), with a single young being born after a gestation of between 196 and 216 days (5) (12). Young are able to run within half an hour of being born, though usually remain hidden in the undergrowth for the first few weeks of life (5) (6). Blue duikers become mature at around a year old, after which they are driven from the parental territory (6) (10), and are reported to live for up to ten years (2) (9).