Philantomba monticola
The blue duiker (Philantomba monticola) is a small antelope found in western, southern and eastern Africa. It is the smallest duiker. The species was first described by Swedish naturalist Carl Peter Thunberg in 1789. 12 subspecies are identified. The blue duiker reaches 32–41 centimetres (13–16 in) at the shoulder and weighs 3.5–9 kilograms (7.7–19.8 lb). Sexually dimorphic, the females are slightly larger than the males. The dark tail measures slightly above 10 centimetres (3.9 in). It has short, spiky horns, around 5 centimetres (2.0 in) long and hidden in hair tufts. The subspecies show a great degree of variation in their colouration. The blue duiker bears a significant resemblance to Maxwell's duiker. Activity is diurnal (limited to daytime). Secretive and cautious, the blue duiker confines itself to the forest fringes. Territorial, individuals of opposite sexes form pairs and occupy territories, nearly 0.4–0.8 hectares (0.0015–0.0031 sq mi) large and marked by preorbital gland secretions. The blue duiker feeds on fallen fruits, foliage, flowers and pieces of bark, provided mainly by the forest canopies in their habitat. The age when sexual maturity is gained has been given differently by different studies. The species is monogamous, with pairs remaining together throughout the year. The length of the gestational period has been estimated from as little as four months to as long as seven months. Births occur throughout the year, though the birth rate might fall in the dry season. The calf is mainly kept in hiding and weaning occurs at 2.5 to 3 months. The habitat consists of 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. Though categorised as Least Concern by the International Union for Conservation of Nature and Natural Resources (IUCN), the blue duiker is under threat from extensive bushmeat hunting across its range. The scientific name of the blue duiker is Philantomba monticola. It is placed in the genus Philantomba, along with Maxwell's duiker (P. maxwelli) and Walter's duiker (P. walteri), and the family Bovidae. The species was first described by Swedish naturalist Carl Peter Thunberg in 1789. It is sometimes treated as a species of Cephalophus, another genus of duikers, although Philantomba has been recognised as a genus by zoologists such as Peter Grubb and Colin Groves. Owing to the remarkable similarities between the two species, some zoologists such as Theodor Haltenorth consider Maxwell's duiker as a race of the blue duiker. While the generic name Philantomba has no clear origin, the specific name monticola has been derived from the Latin words montis (mountain) and colo (meaning 'I cultivate' or 'I inhabit'), in reference to its montane habitat. The common name 'blue' refers to one of its typical coat colours. The common name of duiker comes from the Afrikaans duik or Dutch duiker – both mean 'diver', which refers to the practice of the animals to frequently dive into vegetation for cover. In 2012, Anne R. Johnston (of the University of Orleans) and colleagues constructed a cladogram of the subfamily Cephalophinae (duiker), that includes the three genera Cephalophus, Philantomba and Sylvicapra, based on mitochondrial analysis. Philantomba was shown to be monophyletic. It is sister to the rest of the subfamily, from which it diverged nearly 8.73 million years ago (in the late Miocene). The blue duiker split from Maxwell's duiker 2.68 to 5.31 million years ago. This cladogram, however, did not include the newly discovered Walter's duiker. Marc Colyn (of the University of Rennes 1) and colleagues, who had discovered this species in 2010, had prepared a similar cladogram (below) that included it. As many as 16 subspecies of the blue duiker have been proposed. In 1997, Jonathan Kingdon demarcated seven major populations of the species. In 2001, Groves and Grubb identified the following subspecies, bifurcating them into two groups on the basis of their colouration and geographical occurrence:
