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
San Benedicto Island location where several seabirds of the tropical Eastern Pacific come to breed. Taxa breeding on San Benedicto are: The nearly extinct Townsend's shearwater ("Puffinus auricularis") does not seem to breed on San Benedicto, but can sometimes be seen feeding offshore. Given that there are no invasive species on San Benedicto and also no predators apart from the frigatebirds, the island might be highly suitable for establishing a new colony. Indeed, it bred here before the 1952 eruption; shearwaters are highly conservative in choosing their breeding locations, which explains why San Benedicto has not yet been recolonized. Vagrants of other species,