The only land birds that migrate regularly to and from New Zealand are two species of cuckoo – the long-tailed cuckoo, Eudynamis taitensis, and the shining cuckoo or pipiwharauroa, Chalcites lucidus. Both winter in island groups to our north, the shining cuckoo spending from about April to August inclusive in the Solomon, Louisiade, and Bismarck Archipelagoes, which lie east of New Guinea and some 2,000 miles from New Zealand.
Shining cuckoos make their landfall along our coasts about September or early October, the date of their arrival in various localities showing some variation from year to year. During the ensuing few weeks they spread throughout the country to as far afield as Stewart Island and the Chathams. Most forested areas are occupied and, after recovering from the stresses of their long journey, the cuckoos breed. Within New Zealand proper the grey warbler is the main species parasitised. On the Chathams, where this species is absent, the Chatham Island warbler is parasitised instead. The single greenish-brown egg is most commonly laid in the nest of the host species' second clutch for the season. After about 12 days of incubation by the warblers the young cuckoo hatches and soon, by purely instinctive behaviour, ejects any warbler eggs or young. Equally instinctively, the adult warblers feed the young cuckoo, which is able to leave the nest when about two weeks old. Other species that are sometimes parasitised are the tomtit, fantail, silvereye, and even the chaffinch and house sparrow.
The return migration of “parent” cuckoos and birds of the year occurs about March, though a number of late-hatched birds “overwinter” in New Zealand.
Pipiwharauroa are small birds which may be identified by their conspicuously cross-barred underparts and bright golden-green upper parts tinged with copper. The song is very characteristic – a long series of double notes increasing in volume, which sounds like someone whistling a dog. This phrase is usually followed by one or more downward slurs and a chirrup.
Cuckoos are insectivorous, eating a number of kinds of caterpillar and other orchard pests.
by Gordon Roy Williams, B.SC.(HONS.)(SYDNEY), Lecturer in Agricultural Zoology, Lincoln Agricultural College.