Tuatara: Volume 21, Issues 1 and 2 (New Zealand Albatrosses and Petrels: an Identification Guide)
7. Grey-Headed Mollymawk — (Diomedea chrysostoma) — Plate 4
7. Grey-Headed Mollymawk
Field Characters: 213/84. A medium-sized mollymawk with a grey head and neck, the colour of which merges evenly into the black colour of the back. Cap pale grey. Underbody white. Underwing white, with moderately broad, sharply defined, black margins. The black leading margin is widest around the elbow joint, where it forms a distinct curve. It then narrows and broadens again just outside the carpal joint, to form a black finger patch. The black margin at the trailing edge of the underwing is significantly narrower. Juveniles have a darker grey head and neck contrasting sharply with the white breast. A distinctive white cheek patch is often present, and the underwing is entirely dark.
Bill of adults lemon-yellow top and bottom with a pink hook. Sides of bill, black. The bill of juvenile birds is dark blackish brown. feet bluish-white.
Differs from Buller's Mollymawk (8) by the absence of a white cap and the curving (not straight) leading margin on the underwing (cf. Fig. 7a, Pl. 4, with Fig. 8b, Pl. 5).page 23
Flight is the usual mollymawk soaring and swooping with stiffly held wings, but this species does not follow ships, although odd birds may gather around stationary vessels.
Circumpolar in distribution. Breeds locally on Antipodes, Campbell and Macquarie Islands. Ranges widely in New Zealand waters.