Desertas petrel
The Desertas petrel ("Pterodroma deserta") is a small seabird in the gadfly petrel genus which breeds on Bugio Island in the Desertas off Madeira. The gadfly petrels in the genus "Pterodroma" are seabirds of temperate and tropical oceans. Many are little-known, and their often similar appearance have caused the taxonomy of the group to be rather fluid. Although the systematics on this species has not yet been definitively established, provisionally some authorities have split the Desertas petrel, separating the Desertas breeding birds from those in the Cape Verde archipelago, while others consider it a subspecies of the  Fea's petrel. The species is named after its breeding grounds, which are pronounced "Dez-ERT-ass". Description. As all three of the species in the "Pterodroma feae/madeira/desertae" complex were once believed to be subspecies of a single species: "Pterodroma mollis", the extreme difficulty in telling them apart is easily understood. A summary of data from a morphological study sheds light on the issue: In terms of ratios: References.