At Gough Island (and also the Tristan group), the taxonomy of storm-petrels with white bellies is debated. It has been suggested that a white-bellied morph of Black-bellied Storm-petrel Fregetta tropica occurs here. Although their plumage appears close to White-bellied Storm-petrel Fregatta grallaria, their biometrics and certain other features have been suggested to indicate affinities with Black-bellied Storm-petrel Fregatta tropica. See discussion by Howell, 2010, Dutch Birding 32: 36-42, who concluded that the taxonomy and identification of the group was confused (and that further crypto-species might also be involved). In the image above, the black hood extending no further than the leading edge of the wing, and the relatively narrow and cleanly-demarcated black leading-edge to the underwing are plumage features associated with White-bellied Petrel and that attribution is followed here.

© A. R. Dean