Boa Vista is the only breeding location of the Magnificent Frigatebird in the Western Palearctic. At present, the species does only nest on Curral Velho islet, off the southern coast of the island. The breeding period is from November to June.Human persecution and, more recently, persistent reproductive failures are thought to have brought the small Cape Verde frigatebird population on the verge of extinction. Population size in 2007 was 4-5 individuals - 2 females and 2-3 males. Currently, a single pair survives, which is expected to become extinct within the next decade.
The Red-billed tropicbird is the only seabird species that nests chiefly on Boa Vista’s mainland, with coastal cliffs being the preferred nesting habitat. The breeding season is prolonged, starting in late August-early September and ending in late June-early July, with a peak of nesting activity between October and January. During the past decade, the number of tropicbird breeding pairs in Boa Vista has declined with about 40%. At present, the population may range between 100-150 pairs. Heavy persecution by local people and predation by feral cats are the two major threats to the survival of the species on this island.
With about 80 pairs, Cape Verde harbours the largest island population of Ospreys in the Western Palearctic. Most pairs are concentrated in the windward northern islands. The breeding period is from December to May. In Cape Verde, Ospreys nest on the ground, chiefly in coastal areas. Because of coastal development and human pressure, many Osprey pairs in islands like Boa Vista have moved to the mountainous inland areas. With around 20 pairs, the Osprey population in Boa Vista is one of the largest of the sedentary island populations in the Western Palearctic. Nonetheless, productivity has been estimated as among the lowest. Only a single young has successfully fledged in the last two breeding seasons (2012 and 2013) from 22 nests where breeding activity was reported. Nest failure was chiefly due to predation by the Brown-necked raven. Other threats came from human disturbance and depredation.
Biogeographically, Cape Verde is situated at the south-western border of the Western Palearctic region. Birdlife International has designated these islands an ‘Endemic Bird Area’. There are about 43 breeding species, of which 15 can be regarded as endemic. Birds are among the natural resources of Cape Verde that have historically been subject to strong anthropogenic pressure. Depredation of birds by humans is deeply embedded in the culture of the Cape Verde people and many seabird colonies in the archipelago have been decimated, indeed exterminated, since colonization started in the 15th century.
Boa Vista is one of the islands with a rather rich diversity of bird species. Currently, morethan 20 different species breed here. A large diversity of migratory species can be found in the wetland areas of this island, particularly between late December and early May. Six out of the nine seabird species existing in Cape Verde breed in Boa Vista: Cape Verde shearwater Calonectris edwardsii, White-faced storm petrel Pelagodroma marina, Cape Verde storm petrel Oceanodroma jabe jabe, Red-billed tropicbird Phaethon aethereus, Brown booby Sula leucogaster and Magnificent frigatebird Fregata magnificens. Most of these species nest on islets off the main island, such as the islets of Curral Velho, Baluarte and Pássaros.
Among the desert birds, cream-coloured courser Cursorius cursor, greater hoopoe lark Alaemon alaudipes, bar-tailed desert lark Ammomanes cinctura and black-crowned sparrow lark Eremopterix nigriceps are the most typical species. Gallinaceous or chicken-like birds are represented by quail Coturnix coturnix and guinea fowl Numida meleagris, the latter being an introduced species. Osprey Pandion haliaetus, egyptian vulture Neophron pernocterus, Alexander’s kestrel Falco alexandri and Cape Verde barn owl Tyto detorta are the raptor species nesting in the island.Kentish plover Charadius alexandrinus is the only breeding shorebird. Finally, the endemic Iago sparrow Passer iagoensisas well as spectacled warbler Sylvia conspicillata are widespread throughout the island. Blackcap Sylvia atricapilla breeds locally in small numbers.
During the past decade, tourist development and the resulting growth in human population have had, both directly and indirectly, serious detrimental effects on habitats and populations of most of the species making up the avifauna of Boa Vista. Also, due to the growth of the human population, opportunistic bird predators, both indigenous (i.e. Brown-necked ravens, Corvus ruficollis) and non-indigenous (i.e. feral cats) have found better conditions to thrive and increase their numbers.
Most wetland areas, priority habitats for the conservation of birds in Cape Verde, are subject to degradation and destruction due to human activities. Two Ramsar sites exist in Boa Vista: Ribeira d’Água (or Ribeira de Rabil) and Curral Velho. Main threats to wetland areas come from human disturbance (i.e. circulation of people and motorized vehicles and water sports) and degradation (i.e. water pollution because of run-off, fuel and oil spills, sand mining, and water extraction for agriculture and construction).