St Levan common species such as northern gannet ("Morus bassanus"), Manx shearwater ("Puffinus puffinus"), common guillemot, ("Uria aalge") and razorbill ("Alca torda"), as well as rarer birds such as Balearic shearwater ("Puffinus mauretanicus") and Cory's shearwater ("Calonectris borealis"). The headland of Tol-pedn (or Gwennap Head) is favoured by birdwatchers and many travel the length and breadth of Britain to track rare seabirds. Some of the butterflies that can be found on the coast include grayling ("Hipparchia semele"), silver-studded blue ("Plebejus argus"), small pearl-bordered fritillary ("Boloria selene") and wall ("Lasiommata megera"). There is also a day-flying moth, the thrift clearwing ("Synansphecia muscaeformis"); the
Procellariidae with "Pseudobulweria" being phylogenetically closer to the "Puffinus" shearwaters than the "Pterodroma" gadfly petrels, and "Aphrodroma" (the Kerguelen petrel) possibly being closely related to the shearwaters or the fulmars. The prions, according to Nunn and Stanley, were among the larger shearwater group. The "Calonectris" shearwaters were placed close to the two "Puffinus" clades (closer to the Puffinus, or small, clade) and both were distant to the "Procellaria" shearwaters. The relationships between the genera and within the genera are still the subject of debate, with researchers lumping and splitting the species and genera within the family and arguing about the position