Several million seabirds breed around New Zealand, and then migrate across the equator to the far north Pacific. Others move east or west from New Zealand across the Tasman Sea, or to the eastern Pacific and western Atlantic.
Albatrosses and petrels
In contrast to the solitary breeding habitat of most Arctic waders, many albatrosses and petrels that breed in the New Zealand region nest or burrow in dense, noisy colonies on small, predator-free islands. During this time they compete for food within reach of the island.
When breeding is over they have no need for land, and many petrel species migrate to other food-rich areas of ocean or continental shelf. The sooty shearwater or tītī, Buller’s shearwater, flesh-footed shearwater and the mottled petrel move to the northern Pacific. Birds such as the Cook’s petrel, black petrel, Chatham petrel and white-faced storm petrel migrate to the eastern and tropical Pacific. Other birds, including both royal albatross species, migrate to the Atlantic and Pacific coasts of South America, or, like the Hutton’s shearwater, to the waters around Australia.
After fledging, the Campbell albatross flies from Campbell Island to the subtropical Pacific for the winter, then joins adults off the east coast of Australia before returning to breed. Some southern-breeding petrels such as the Antarctic prion move north to New Zealand waters during winter.
Most petrels fly mainly by soaring or gliding, using the wind’s energy instead of their own as much as possible. Also, they rest and feed at sea, so their migration flights are less demanding than waders’.
Terns, gannets and dotterels
Most juvenile and some adult white-fronted terns cross the Tasman Sea to winter on the Australian coast. New Zealand-hatched Australasian gannets and one wader species – the banded dotterel – also do this.
Two species of cuckoo are the only land-based New Zealand species that migrate overseas. The shining cuckoo or pīpīwharauroa winters in the western tropical Pacific – from Indonesia to Solomon Islands and the Bismarck Archipelago. The long-tailed cuckoo or koekoeā tends to winter further east, from Palau (Micronesia) across to the Marquesas and Tuamotu Islands of French Polynesia. On their return to New Zealand, their distinctive calls are a sign of spring, as in the proverb:
Ka tangi te wharauroa, ko ngā kārere ā Mahuru.
If the shining cuckoo cries, it is the messenger of spring.
For them, the breeding season is not arduous as they lay their eggs in the nests of other birds, which unwittingly rear the chicks.