Study suggests multiple species of Sharp-shinned Hawk

Of the 10 recognized subspecies of Sharp-shinned Hawk, three are found on large neighboring islands of the Caribbean: Cuba, Hispaniola, and Puerto Rico. While their populations and ranges are small, scientists have long presumed that they mix with migratory Sharp-shins from the vast North American mainland population, resulting in less attention from conservation agencies and nonprofits.

A new study of the DNA of Caribbean Sharp-shins, however, has found that the subspecies are genetically distinguishable as their own clade, meaning they evolved from a common ancestor. Furthermore, the research shows the subspecies are different enough from each other genetically and by plumage to be considered separate species.

The authors of the study, published in the July issue of the journal Ornithology, propose that four species be recognized: one for each island and one for the mainland. They note that other Caribbean birds have been elevated to species status based on similar research, including Hispaniolan Crossbill and Bahama Warbler.

They emphasize that the Caribbean Sharp-shins “should be considered as high conservation priorities because of recent population declines resulting from habitat loss, invasive parasitic flies, expansion of nest predators, and hurricanes.”

Puerto Rican Sharp-shins have been listed as endangered in the U.S. for almost three decades. After the devastation from Hurricane Maria in 2017, the population collapsed to only 19 known individuals. The hawks on Cuba and Hispaniola are not listed as birds of conservation concern despite similar decades-long declines.

“Historically, federally listed Caribbean taxa have been the beneficiary of conservation actions and funding at rates disproportionately lower than mainland taxa,” the authors conclude. “Based on multiple lines of molecular and morphological evidence, we advocate that the Accipiter hawks of the Caribbean islands be appropriately recognized as an underappreciated, endemic island radiation of species that require immediate conservation funding and protective action, before these small, declining populations succumb to extinction.”

This article was first published in “Birding Briefs” in the November/December 2021 issue of BirdWatching.