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Between 1987 and 1996, 2,383 wrybills (Anarhynchus frontalis) were banded on their wintering grounds at two locations near Auckland; 690 of these were recaptured on 830 occasions. Birds started to arrive at their wintering grounds in December; and stayed at the more northern location until April, when they moved to wintering sites further south. First year birds comprised <15% of the population, and about 30% of birds were at least 5 years old The maximum longevity in the wild was 16 years. Adults had significantly longer wings than younger birds, hut there was no such difference in bill or tarsus length. Body mass generally increased during winter, and adults often were heavier than young birds. Wrybills moulted between late December and early May. A country-wide population census found 5,111 birds in May 1994. There is no reliable indication that the population ever exceeded this level.