Recent taxonomic research indicates that the two subspecies should become full species; the widespread subantarctic black–browed mollymawk, melanophrys, and the smaller endemic New Zealand black–browed mollymawk, impavida, which breeds only on the Campbell Islands.
This beautiful and common species is the species usually known as the mollymawk. It was first included in the New Zealand fauna on the observation of Hutton who noticed it off Great Barrier Island in 1868. Travers collected it at the Chathams in 1871, and it was discovered breeding at the Auckland and Chatham Islands about the same time.
According to Oliver, steep slopes on the tops of sea cliffs are the breeding sites of the black-browed mollymawk. On the north-east coast of Campbell Island high above the water’s edge is an immense colony, rows and rows of birds being seen from the sea on tussocky slopes with cliffs above and below them. Two species, the black–browed and the grey–headed are associated in these colonies.
The birds arrive in September and by early May all will have left the island. “The strange mud and straw nests, shaped like huge cheeses, are situated about four feet apart — just room enough for incoming birds to walk to their own homes without being pecked by the neighbouring birds. With such intensive settlement the ground becomes heavily fertilised and supports a lush growth of several species of plants. In the late spring, the brilliant green carpet of plants, studded with dark brown nests and occupied by thousands of snowy plumaged, black winged birds, is one of the sights of the antarctic.”
The black–browed molly is the commonest species caught by long line fishing, juveniles being especially vulnerable.
