Systematics and conservation of the hook-billed kite including the island taxa from Cuba and Grenada

Taxonomic uncertainties within the genus Chondrohierax stem from the high degree of variation in bill size and plumage coloration throughout the geographic range of the single recognized species, hook-billed kite Chondrohierax uncinatus. These uncertainties impede conservation efforts as local populations have declined throughout much of its geographic range from the Neotropics in Central America to northern Argentina and Paraguay, including two island populations on Cuba and Grenada, and it is not known whether barriers to dispersal exist between any of these areas. Here, we present mitochondrial DNA (mtDNA; cytochrome B and NADH dehydrogenase subunit 2) phylogenetic analyses of Chondrohierax, with particular emphasis on the two island taxa (from Cuba, Chondrohierax uncinatus wilsonii and from Grenada, Chondrohierax uncinatus mirus). The mtDNA phylogenetic results suggest that hook-billed kites on both islands are unique; however, the Cuban kite has much greater divergence estimates (1.8-2.0% corrected sequence divergence) when compared with the mainland populations than does the Grenada hook-billed kite (0.1-0.3%). Our findings support species status for the Cuban form, as Chondrohierax wilsonii, and subspecific status for the Grenada form. For mainland taxa, we do not find support for the currently recognized subspecies Chondrohierax uncinatus aquilonis in western Mexico, but we do find evidence for a genetic subdivision between populations in Central and South America, a difference previously unsuspected. The results of this study help identify conservation priorities associated with these unique Neotropical raptors. This information is of immediate interest because the Cuban kite has not been reliably seen since 1992, and < 50 hook-billed kites currently inhabit Grenada.