Nearly 200 species of birds can be found on Bioko Island, including the rare Bare-headed Rock Fowl (Picathartes oreas). Bioko also has two endemic bird species, the Fernando Po Speirops (Speirops brunneus) and the Fernando Po Batis (Batis poensis), as well as at least 28 endemic subspecies. Other key species are the Mountain Saw-wing (Psalidoprocne fuliginosa) and Ursula’s Sunbird (Cinnyris ursulae).

Although BBPP has not specifically studied birds on Bioko in the past, since October 2011 we have begun a preliminary population monitoring program in the areas around our Moka Wildlife Center. This ongoing project, in addition to filling in a major information gap about the ecology around the MWC, has become one of the keystone projects of the Drexel Study Abroad Field Research in Tropical Ecology course, including students in an active conservation research project.

Participants on BBPP's annual Caldera expedition often spot the rare Bare-Headed Rock Fowl.

The African Bird Club also had this to say about the avifauna of Bioko

Few birdwatchers have ever visited this small country in West Africa or even know where it is situated. Ornithological records are limited and many areas have not been surveyed. Only about 340 species have been recorded on the mainland, Rio Muni, whilst 198 species have been recorded on the island of Bioko and 19 species on the island of Annobón. Bioko and Annobón both have endemic species and subspecies. It is a country therefore which offers potential opportunities for the professional ornithologist and perhaps much of interest for the more adventurous birdwatcher.