New Zealand Wildlife Service
Department of Internal Affairs
Wellington, New Zealand
Abstract
Marine species (pelagic birds and those of exposed coasts) make up about 48% of New Zealand's native avifauna, excluding stragglers and antarctic species. The biological history that has led to the present status of marine birds in this archipelago of some 700 islands is outlined, methods of conservation are briefly described, and some illustrative case histories of management programs are given. In spite of the major environmental changes that have occurred in New Zealand during 200 years of European occupation, only one marine species has become extinct, although five such endemic species are currently regarded as threatened as are a few subspecies of widely distributed forms.
New Zealand, which lies some 2,000 km southeast of Australia, has been a changing archipelago for many millions of years. It has been separated from any major landmass (first, Gondwanaland and later, Australia) for at least 80 million years.
Before the arrival of man, probably between 1,000 and 1,500 years ago, New Zealand was free of any land mammals except two species of bats, and there were few avian predators. These, among a number of other biological peculiarities, reflect the archipelago's considerable and long-standing isolation.
There are nearly 700 islands 0.5 ha or more in area in the New Zealand region; and, if North, South, and Stewart islands are regarded collectively as the mainland, about 650 of these islands lie within 50 km of the coast and 30 beyond that limit, to about 850 km offshore (Atkinson and Bell 1973). The archipelago extends from about 30° to 52°S lat. (over a distance of about 2,400 km)—that is, from the subtropical to the subAntarctic—and from about 166° to 176°W long. (Fig. 1).
Pelagic and coastal birds must obviously be an important part of the avifauna and, in fact, aside from stragglers, antarctic species, and established introduced species, they make up about 48% of the 173 in the New Zealand Checklist (Kinsky 1970). Of the 83 species I have regarded as marine, 48 (28%) are pelagic and 35 (20%) shorebirds of exposed coasts. Ten of the 48 pelagics (21%) and 12 (34%) of the 35 shorebirds are endemic.
More than a thousand years of occupation by Polynesian man with his commensal Polynesian rats (Rattus exulans) and a peculiar breed of domesticated and feral dog (now extinct), did little damage to pelagic and open coast species, even though many, if not most, were used as food—especially the petrels, and particularly those belonging to the genera Puffinus, Procellaria, and Pterodroma. However, the Europeans, who arrived about 200 years ago, brought with them a menagerie of mammals and birds, and 33 species of each have become established and are now feral (Gibb and Flux 1973; Williams 1973). They also put into practice, on a large scale, European methods of land use that had unfortunate effects on almost the entire native avifauna. Although terrestrial, freshwater, and estuarine species suffered most, marine species suffered also. However, reduction in numbers and range rather than extinction was the rule, except locally.
Apart from habitat destruction by man and the various mammalian browsers and grazers, the most inimical agents have been black rats (Rattus rattus), Norway rats (R. norvegicus), feral cats, and feral pigs. One would expect the inhospitality or inaccessibility of an island to be a marine species' best protection, and so it has generally proved-the greatest losses have occurred on the two major mainland islands (North Island and South Island). Bourne (1967) suggested that Polynesians in pre-European times may have caused the extinction of numerous petrels in the Chatham Islands. There are still a few islands on which no exotic mammals occur, but modern transport, allied with human curiosity and cupidity, are stripping all but the most wild and remote of these of the protection against invasion they have had so far. Cruises by nature-hungry but sometimes environmentally illiterate tourists are beginning to be a local problem.
