Black-capped Petrel

The black-capped petrel is large compared to other gadfly petrels, with a length of about 16 inches (40.5 cm) and 37 inches (94 cm) wingspan. The most similar species within its range is the Bermuda petrel, which is smaller and has a narrower white rump patch and an extensive gray cowl. The great shearwater is also superficially similar. The critically endangered or possibly extinct Jamaica petrel (P. caribbaea) was a related dark form. The local Spanish name, Diablotín, means "little devil" because of its night-time habits and odd-sounding mating calls, which suggested to locals the presence of evil spirits in the dark. The petrel will occasionally utter other croaks and sounds while foraging at sea. The black-capped petrel is nocturnal on its breeding grounds, possibly to avoid predation by gulls, hawks or crows. Like most petrels, its walking ability is limited to a short shuffle to the nest burrow.

Although this seabird once bred on steep mountainsides of the Greater Antilles, only three confirmed breeding areas remain in the high mountains of Hispaniola (in Sierra de Bahoruco and Valle Nuevo National Park in the Dominican Republic, and Massif de la Selle and Massif de la Hotte in Haiti). In 2015, birds were also confirmed nesting on a second island (Dominica), which had long been suspected given historical nesting there. A mountain peak where it formerly bred in Haiti (and another in Dominica) is still named "Mont Diablotin" in reference to the "little devil" moniker. The warm waters of the Gulf Stream serve as the primary foraging area for this species. Most birds during the non-breeding season are concentrated off the United States coast between Florida and North Carolina, though they have been known to wander far to the north and east toward Europe. The species has been seen year-round in the Gulf Stream. The birds that visit these waters during the breeding season either represent non-breeders or are making long foraging trips away from the nest. The black-capped petrel is almost strictly pelagic away from the breeding grounds and is known to join loose flocks with other seabirds such as shearwaters and terns.