Yelkouan shearwater Menorca. A study of these birds recommended that a combination of morphological characteristics and DNA sequence data should be required at least for scientific purposes to assign individual birds to either species. It was formerly considered a subspecies of the Manx shearwater (see there for more on the "Puffinus puffinus" superspecies). After the first split, it was the nominate subspecies of the so-called "Mediterranean shearwater" for nearly ten more years; it is considered a monotypic species now, as the Balearic form "mauretanicus" has been separated as the Balearic shearwater. The yelkouan shearwater appears to belong to a group of Mediterranean
Tropical shearwater Tropical shearwater The tropical shearwater ("Puffinus bailloni") is a seabird in the family Procellariidae formerly considered conspecific with Audubon's shearwater ("Puffinus lherminieri"). There are five listed subspecies of the tropical shearwater: The tropical shearwater is found in the tropical parts of the western Indian Ocean from east Africa to southern India and in similar regions of the Pacific from just to the southeast of Japan to French Polynesia. The total population has not been definitively quantified. Subspecies "P. b. dichrous" is estimated to number 1,000–10,000 pairs on the Line Islands and 10,000–100,000 pairs on the Phoenix Islands, with the nominate