out a whistling call. Diet The diet consists of fallen fruits, foliage, flowers and pieces of bark, provided mainly by the forest canopies in their habitat. Fungi, resin, particularly exudates from Albizia species and animal matter such as ants (which are licked from the ground) may also be included in the diet. The blue duiker can sustain itself on dead foliage better than other duiker species. A 1990 study analysed 12 stomachs and determined the content of dicotyledonous leaves to be 70%, while fruits and seeds comprised 23% of the diets and fresh foliage was plenty and perennial. Fruits were, however, strongly preferred to foliage. In 2001, American zoologist Don E. Wilson observed 18 stomachs, and concluded that nearly three-fourths were occupied by fruits, browse took 15 percent of the volume, while fungi and flowers took 5 percent each. They may forage by tracking the movements of birds and monkeys. Reproduction The age when sexual maturity is gained has been given differently by different studies. Wilson observed that females become mature before 13 months, and the minimum age was found to be eight months. He noted that males take longer to mature, nearly 11 to 14 months. The species is monogamous, with pairs remaining together throughout the year. The length of the gestational period has been estimated from as short as four months to as long as seven months. The former estimate is supported by observations in the Ituri Rainforest (Democratic Republic of Congo). Births occur throughout the year, though the birth rate might fall in the dry season. The calf can start moving about on its own within 20 minutes of birth, and is nursed thrice a day. It is kept in hiding for most of the time. The nursing intervals become irregular towards weaning, which occurs at 2.5 to 3 months. Males visit their mates occasionally, though they disappear for about a month after the calf's birth to probably protect the calf. A postpartum oestrus occurs three to five days after the birth. Habitat and distribution This species can survive in a variety of forests, including old-growth, secondary and gallery forests. Forests are preferred as these provide the animal with shelter through the dense understory and forage through canopy. They can also be found in pockets of degraded and regenerated forests from the sea level up to an altitude of . This duiker can be found in several