Shining Cuckoo
Maori Name: Pipiwharauroa
Scientific Name: Chrysococcyx lucidus
From NZ Birds Online:
The Shining Cuckoo is a spring/summer migrant, laying its eggs in the nests of Grey Warbler "foster parents". These birds are found mainly in stands of willow, eucalypt and some of the taller native plantings, such as at Styx Mill Conservation Reserve. This species leaves New Zealand in April and migrates to wintering areas on islands in the South-West Pacific.