Brown skuas (Catharacta skua lonnbergi) on rangatira (south east) and mangere islands in the chatham islands group were studied over a period of 14 years (1978/79 to 1992/93 breeding seasons) to determine factors promoting cooperative breeding in this population. The size and composition of the breeding population and overall breeding success were remarkably stable. No significant differences in breeding success, density of territories or periods of individual occupation in different places on these islands were demonstrated that would demarcate optimal and marginal breeding habitat. Neither could it be demonstrated that the islands were saturated by breeding birds as required for a habitat-forced origin of cooperative breeding.
The migration pattern of Cattle Egrets in 1990 and 1991 and its relation to meteorology are presented to extend initial results covering 1987-1989 (Maddock & Bridgman 1992). Cattle Egrets migrated to Victoria and Tasmania in waves during March and April in northerly air flow (western side of a high pressure system) in a series of stages, with periods of rest in between. Major staging points seemed to be Windsor (NSW), Nowra (NSW), and Baimsdale (Vic). Return migrations (October and November) appeared faster, with fewer and shorter rest stops, and were in southerly airflow. Staging points were Werribee (Vic), Nowra (NSW), and Wyong (NSW). Migrations to and from New Zealand were much more limited than in previous years due to adverse weather conditions, especially winds.
Records of Chatham Petrel (Pterodroma axillaris) up to 1989 are reviewed. A research programme that started in the breeding season of 1989/1990 to locate more individuals and more active burrows is described. Several methods of locating birds were employed and status of all burrows, and breeding success and measurements of all birds were recorded. The population at the end of the 1991/1992 breeding season is estimated. Conservation issues presented by the species are discussed.
The Chatham Island Taiko (Magenta Petrel) Pterodroma magentae is endangered, with a population of about 50 birds. Conventional searches from 1970 to 1986 failed to find its breeding sites. Trials of radio transmitter packages attached to Grey-faced Petrels P. macroptera gouldi and to six Taiko in 1982-1986 were satisfactory. In a major effort to find burrows, Taiko were caught and radio-tracked over three months in late 1987. Twelve Taiko were caught at night with the aid of lights. Ten birds were each fitted with a transmitter; all flew out to sea after release. Birds were tracked on 16 later occasions. Two tracked birds landed 4-6 km inland in dense bush. On subsequent searches at the bearings at which the signals became stationary, five burrows were found, in two areas, 4 km apart. During a similar operation in 1988 no Taiko were caught. Despite extensive searches, these were still the only breeding areas known in late 1993.
In 1992, participants of the Beach Patrol Scheme patrolled 4114 km of the New Zealand coastline. 5994 dead seabirds of 53 species plus 143 individuals of 30 other bird species were recovered. The number of seabirds found in 1992 was only 59% of the annual average of 10 187 between 1971 and 1992, and was the seventh consecutive year that below average numbers of dead seabirds have been found. The Common Noddy (Anous stolidus pileatus) was recorded for the first time since the start of the Scheme, providing the second record of this species in New Zealand. Thirteen Little Shags (Phalacrocorax melanoleucos) were found, more than the average of 5-10 per year during 1971-1992. 14 833 specimens of three species of gulls were recovered between 1943 and 1992. The majority of recoveries (10 190 bids) was that of the Southern Black-backed (Larus d. dominicanus), which was found mostly near coastal cities when birds dispersed from the colonies after the breeding season. 4195 Red-billed Gulls (L. novaehollandiae scopulinus) were found during 1943-1992, mainly along the eastern coasts of New Zealand. Only 448 Black-billed Gulls (L. bulleri) were found during the same period, mainly on eastern South Island beaches.
In the last issue, the title of R. Schuckard’s paper (Notornis 41: 93-108, 1994) should read: ‘New Zealand King Shag (Leucocarbo carunculatus) on Duffers Reef, Marlborough Sounds’ In the Abstracts, the sentence starting on line 9 should read: ‘During the six months of courtship/breeding period, daily rhythm of the colony was different from the rest of the year; high numbers of birds departed in the early morning and afternoon.’
Between 1960 and May 1993, 62 species of seabirds were recorded at Chatham Islands, including 43 procellariiforms, 5 penguins, 5 pelecaniforms, and 9 Lari. Apart from the 24 breeding species, there were 14 regular visitors, 13 stragglers, 2 rarely seen on migration, and 9 found only beach-cast or as other remains. There is considerable endemism: 8 species or subspecies are confined, or largely confined, to breeding at the Chathams.
In late July and early August, 1993, the survey of Fiordland Crested Penguins on Codfish I. initiated by Department of Conservation personnel in 1992, was completed. From 11-19 August we surveyed the coasts of southern Stewart and the Titi Is, and from 21-23 August we surveyed Solander I. A total of 115 Fiordland Crested Penguin nests and 300 birds were counted: 5 birds on or near Codfish I., 32 birds around southern Stewart I., and 115 nests and 263 birds on Solander I. Solander I. has been added to the small number of locations where more than 100 penguin nests are found annually. The survey has now covered all of the range of the Fiordland Crested Penguin except for the mainland north of Milford Sound; our estimate of nests in the surveyed area is about 1000 annually.
Morphometric data are presented for the northern and southern populations of the NZ Dotterel. There are significant differences between the two populations in all measurements of birds and eggs. The differences in midtoe and adult weight are pronounced: the former yields a Coefficient of Difference above the conventional level of subspecific difference. Plumage differs between birds of the two populations. Ecologically and behaviourally the two populations differ distinctly; southern birds breed inland and northern birds on the coast, the timing of flock break-up and movement to breeding sites is different and the ranges of the two groups are discrete. Based on these differences, the two populations are accorded subspecific status, and a new subspecies is described.
South East Island (Rangatira) is the most important reserve for oceanic and terrestrial bird life in the Chatham Islands, and one of the largest islands free of mammalian predators in the New Zealand region. The avifauna consists of 66 species: there are confirmed records of breeding or attempted breeding for 33 of these. The rest are either vagrants or forage in adjacent waters. Two species, Shore Plover Thinornis novaeseelandiae and Chatham Petrel Pterodroma axillaris breed only on this island. A further six species are endemic to the Chathams, but are rare elsewhere in the group; five of them are abundant. Historical and contemporary records are covered. During the past 150 years, the vegetation of the island has been altered substantially, by fire and grazing. The changes have influenced the fauna greatly, and its original composition and character are unclear.