52. Black-Bellied Storm Petrel
(Fregetta tropica)
Plate 19

Field Characters: 45/20. A large storm petrel with sooty brown upperparts (appearing black at sea), and a prominent white ‘rump’ patch formed by the white flanks and uppertail coverts. Upperwing sooty brown, with an inconspicuous grey brown crescent, formed by the somewhat lighter colouring of the greater secondary upperwing coverts. Underparts similar to White-bellied Storm Petrel, except that the dark colouring of the throat extends on to the breast. The belly is white with a black central line, usually extending from the black breast to the black undertail coverts. This black belly stripe, however, is individually variable in width, and can be occasionally absent. Underwing white in centre, with broad black margins. Tail square.

Bill and feet, including webs, black.

Differs from Grey-backed Storm Petrel (50) by its larger size, white rump patch and black belly stripe. Distinguished from White-bellied page 52

Fig. 17: Head study of a Black-bellied Storm Petrel (Fregetta tropica). Note small, slender bill and conspicuous nostril tubes typical of storm petrels.
— Photo: P. C. Harper

Storm Petrel (51) by uniformly sooty brown mantle and back, and black belly stripe. This last distinguishing character, however, is not always easy to observe at sea.

Flight similar to other storm petrels, but with more erratic zig-zagging and swinging from side to side, alternatively exposing its under and upper surfaces.

Circumpolar in distribution, this species is a late summer breeder at the Antipodes, Bounty and Auckland Islands. Although common in the subantarctic and ranging north in the winter, it has only rarely been reported from New Zealand coastal waters.