Publications Archive

From 1963 to 1981 data were collected on the breeding of the Buller’s shearwater (Puffinus bulleri). The world population, roughly 2.5 million birds, occupies 7 of the 12 islands, islets, and stacks of the Poor Knights Islands (35°30’S; 174°44’E). Buller’s shearwaters return from their 4.5 month trans-equatorial migration on about 10 September. Numbers build up rapidly with breeding birds digging burrows averaging 1.01 ± 0.2 m in length. Caverns, caves, and Maori stone walls also serve as nest sites. Nest refurbishing is complete by about 26 October, when copulation occurs. The prelaying exodus follows about 32 h later, with most birds absent from the isIands’ vicinity for about 30 days until 25 November. Eggs appear from 26 to 30 November. Females without nests lay eggs on the ground until 3 December; these eggs are eaten by tuataras and small lizards. Average dimensions of 74 eggs were 65.44 ± 0.29 x 42.96 ± 0.22 mm; and average weight of 27 fresh eggs 66.76 ± 0.85 g. Surface eggs are narrower than burrow eggs. The incubation period is c. 51 days with both sexes sharing duties. Four nights is the average shift; females sit the first night and following day. Hatching occurs about 19 January; most fledglings leave the islands in early May. Most of the few adult P. bulleri that die on the breeding grounds are ensnared in tree saplings. Numbers on Aorangi have expanded rapidly from c. 100 pairs in 1938 to about 200,000 pairs in 1981. P. bulleri is an aggressive coloniser, displacing gadfly petrels and smaller shearwaters for nesting space. and may soon be colonising the Three Kings and other nearby islands.

An albinistic juvenile Australasian harrier (Circus approximans gouldi) was trapped near Huntly, Waikato. Limited observation of the bird prior to capture suggests that its general behaviour and relationships with conspecifics and other species were normal. The bird’s plumage is described and contrasted with that of normal harriers and the nature of its soft parts is discussed. Other occurrences of aIbinism in the Australasian harrier are given.

In central Westland, 110 western wekas (Gallirallus australis australis) were marked between August 1975 and May 1978, and 38 corpses were examined. Wekas occurred throughout the study site but preferred ecotonal scrublands while avoiding dense forest. Captures fell by 50% over the study period and the number of sightings also decreased significantly. Adults were sexed by a discriminant function based on the bill measurements of dead birds, with a probability of misclassification of live adults of about 4.6%. A sex ratio biased towards males was revealed. Breeding began in late June/July when both sexes had attained maximum annual body weights and fat reserves. Home ranges were generally less than 4.5 ha. The main foods identified from birds collected during June-August and in November were fruits of indigenous forest plants, especially Coprosma spp., and plant foliage, insects and earthworms.