Two species of hoofed mammals, both small forest-dwelling antelope called duikers, inhabit Bioko Island: Ogilby’s duiker (Cephalophus ogilbyi ogilbyi) and blue duiker (Philantomba monticola melanorheus).
Ogilby’s duiker is widespread on Bioko Island, and has a moderate range in coastal rainforest stretching from Nigeria to Central Africa. There are, however, no Ogilby’s duikers in zoos (September, July 2011). Like the other small forest antelope, it is hunted as bushmeat throughout its range. In the Malabo market, an adult Ogilby’s duiker can sell for up to $170.00. The number of Ogilby’s duikers brought to market is declining, even as the price for its meat is increasing. It is now found only in the more remote parts of the island's two protected areas.
Blue duikers are found throughout Bioko Island. The subspecies, P. m. melanorheus, is endemic to Bioko Island. They are much smaller than Ogilby's duiker and weigh around 10 pounds. About 160 blue duikers are held in captivity, although none are positively identified as the Bioko subspecies.