Progne cryptoleuca

Endemic as a breeding bird to Cuba, the wintering grounds of this species are unknown (like those of Antillean Nighthawk) due to the species' uncanny similarity to its sister species, Purple Martin, which breeds widely across North America. Huge numbers of Purple Martins winter in Amazonian Brazil, as well as even further south, but to date no Cuban Martins have been identified in their midst. The Purple Martin also passes through Cuba to and from its breeding grounds, thus even on Cuba and especially during migration periods careful checking can be needed to check which species you are watching. Cuban Martins occur throughout the main island of Cuba, where it is a common breeding bird even in the centre of Havana. They start arriving back in Cuba as early as the end of January, although they don't start becoming very common or widespread until about mid March. Males of the two species are basically indistinguishable, so unless a female is perched handily nearby...