ID provisional. This could be one of the recently discovered smaller-billed form of Broad-billed Prion breeding on Gough Island. This new form is treated by some as MacGillivray's Prion and split from Salvin's but taxonomy uncertain. The steep forehead on this individual is more typical of Broad-billed Prion. The new form reportedly has a more sloping head profile. Canon PowerShot SX50 HS
Reference:
Ryan, Peter & Bourgeois, Karen & Dromzée, Sylvain & Dilley, Ben. (2014). The occurrence of two bill morphs of prions Pachyptila vittata on Gough Island. Polar Biology. 37. 727-735. 10.1007/s00300-014-1473-2.