Tuatara: Volume 21, Issues 1 and 2 (New Zealand Albatrosses and Petrels: an Identification Guide)
8. Buller's Mollymawk — (Diomedea bulleri) — Plate 5
8. Buller's Mollymawk
Field Characters: 208/81. Somewhat smaller than Grey-headed Mollymawk (7), which it superficially resembles, but has a larger head. Head and neck grey, with distinctive white cap, the grey neck colour contrasting with the white upper breast. Underwing white, with moderately broad black leading margin and narrow trailing margin. The leading margin is well defined, and widest at the axilla, with its inner edge more or less parallel to the leading edge of the wing (cf. Fig. 8b, Pl. 5, with Fig. 7a, Pl. 4). With juveniles the head and neck are entirely grey, without white cap, but the underwing is identical to that of adult birds. Juvenile birds of this species are therefore easily distinguishable from juvenile Grey-headed Mollymawks (7).
Bills of adult birds are bright yellow top and bottom with the sides black. With juveniles the bill is dark blackish-brown. Feet bluish flesh in colour.
Differs from Grey-headed Mollymawk (7) by its white cap and by the straight (not curving) black leading margin on its underwing. Flight as for other mollymawks. Follows ships readily and is a voracious offal feeder, competing for scraps with larger species around fishing vessels.
Breeds on Chatham, Solander and Snares Islands and ranges west to eastern Australia and east to South America. Common in New Zealand waters throughout the year.