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Yellowheads (Mohoua ochrocephala) have disappeared from many parts of the South Island. The northernmost self-sustaining populations now occur in Arthur’s Pass National Park, where we surveyed Yellowheads in the Hawdon River Valley during their breeding in 1983 and 1984. Survey techniques were developed for assessing Yellowhead numbers at low densities. In 1983, 11 breeding pairs were found in 500 ha of forest, and in 1984, 21 breeding pairs were found in 2900 ha. About 70% of the birds occurred as breeding pairs, and the rest were itinerant non-breeders and helpers at nests. Yellowheads were spread throughout the valley but were more common at low altitudes. Breeding pairs preferred red beech (Nothofagus fusca) forests. There is some evidence that the nationwide decline of the species is continuing in the Hawdon River Valley.