Zoogeography

Abstract:

We conducted fieldwork on Bonaire and Curaçao, Netherlands Antilles, to assess the distribu- tion and abundance of resident diurnal raptors. In total, seventy-three 1 km2 sample plots were selected following a stratified random method and three landscape types were distinguished, i.e. cultivated area, hills and terrace. The diurnal raptors observed were the Crested Caracara Caracara plancus (93 records), White-tailed Hawk Buteo albicaudatus (37), and the American Kestrel Falco sparverius (44 on Curaçao only). In the hills and on the terraces, all species were more abundant on Curaçao than on Bonaire. Caracaras were found significantly more in hills compared to terraces or cultivated land on both islands, as did White-tailed Hawks on Curaçao. The American Kestrel made more use of cultivated area and least of hills. As detection of the raptors did not seem to differ between the landscapes and between the islands, we infer that the observed differences in distribution are a true reflection of their habitat use. Our results suggest that the ongoing urbanization on Curaçao and Bonaire may lead to a decline in the Caracara and the White-tailed Hawk. For the American Kestrel, cultivated areas – including urbanized parts – apparently provide the open area the birds need for hunting. 

Data presented herein provide records of four species of bats new to the fauna of the Antillean island of Saba — Monophyllus plethodon, Ardops nichollsi, Tadarida brasiliensis, and Molossus molossus. Together with three species previously recorded from the island – Brachyphylla cavernarum, Artibeus jamaicensis, and Natalus stramineus – the chiropteran fauna of the island is documented to be composed of seven species. Our analysis of species/area relationships for West Indian bats provides a slope value of z = 0.177 and R2 = 0.76; therefore, the bat fauna of the West Indies has the flattest slope for this relationship of any West Indian group. This relationship is best explained by a propensity for over water dispersal by West Indian bats. We propose to unite the chiropteran faunas of the islands of Anguilla, Antigua, Barbuda, Nevis, Saba, St. Barthélemy, St. Eustatius, St. Kitts, and St. Martin by recognizing them as the Northern Antillean Faunal Area. Given the small size of Saba (12 km2) and the even smaller effective habitat for non-molossid bats (4 km2), conservation concerns are expressed for the future of the fauna and some recommendations are made for its preservation.