Publications Archive

Twelve Little Spotted Kiwi (Apteryx owenii) were introduced to Red Mercury Island in July 1983. We radio-tagged nine Little Spotted Kiwi on Red Mercury Island before brodifacoum rat poison (‘Talon’) was air-dropped and hand-spread to eradicate kiore (Rattus exulans). All nine birds survived the apparently successful eradication operation. We expect that the population of Little Spotted Kiwi will continue to grow from the 11 pairs we estimated in September 1992, as the absence of rats should improve the availability of invertebrate prey. Populations of other forest birds did not appear to be harmed by the poison either.

The brushtail possum (Trichosurus vulpecula) is an opportunistic herbivore feeding mainly on leaves supplemented by a variety of other plant materials. Possums are known to eat more than 100 native plant species and a wide range of introduced plants. Diet varies markedly between regions but within any particular region is concentrated on a few plant species (Green 1984). In addition to plant material, possums will eat invertebrates (Gilmore 1967, Clout 1977, Warburton 1978, Morgan 1981, Cowan & Moeed 1987) and small vertebrates, such as birds (Perham 1924, Morgan 1981) and mice (Cowan 1990). Captive possums readily accept meat (Cowan 1990). This article describes remains left by possums that have fed on birds and their eggs. Feeding trials were carried out with captive possums to see whether they would eat dead birds and eggs and to see what sign remained after feeding. In addition, we have brought together various accounts of possums preying or scavenging on birds and other animals.

Historical records of South Island breeding of NZ Dotterel (Charadrius obscurus) are discussed. The latest discovered South Island breeding record was 1881. No record of South Island coastal breeding was found. Numbers of birds wintering on the Southland coast declined substantially and rapidly from 1972 to 1992. The cause of decline is believed to be a decline in the Stewart Island breeding population. Colour-banded adults had allegiance to a specific wintering ground. Food items of birds at Stewart Island included 10-20 mm juvenile flounders.

The Chocolate Albatross of Latham (which was the foundation of Diomedea spadicea of Gmelin, 1789) was based for all relevant taxonomic purposes on the painting by Sydney Parkinson of a Wandering Albatross taken in 1768 in the South Atlantic Ocean off the Rio de la Plata, Daniel Solander’s manuscript description of the specimen indicates it was probably an example of the population breeding at the Tristan da Cunha group and Gough island, in which case dabbenena of Mathews, 1929 as the name of the subspecies would be pre-dated by 140 years by spadicea of Gmelin, 1789. Continuing confusion over the identity of the population to which the Wandering Albatross described by Linnaeus belonged has prompted a full examination of the sources on which he based his Diomedea exulans. As a result of this examination it is concluded that exulans as the name of the nominate subspecies of the Wandering Albatross is properly applicable to the larger southern populations which breed at South Georgia, Marion and Prince Edward, Gozet, Kerguelen and Macquarie Islands.

The Wellington branch of the Ornithological Society of New Zealand counted coastal birds along the shores of Wellington Harbour every month for two years in 1975-77 and again in 1986-88. Between the two surveys, giant petrels and Black-backed Gulls, which feed on offal, showed significant population declines; however, most other key species increased, particularly Little Shags, Little Black Shags and Mallards, presumably as the health of the harbour improved as discharges from abattoirs and sewer outfalls were reduced. The distribution of some species changed markedly between the surveys, away from Ngauranga and Pencarrow Head to Moa Point and Owhiro Bay, where raw sewage continued to be discharged into the sea.

The population dynamics of a local group of Kea (Nestor notabilis) was studied at a refuse dump in Arthur’s Pass National Park over the course of three successive summers. The mean number of birds that foraged at the dump during the summer was estimated as 20 juveniles, 10 subadults, and 36 adults. An average of 11% of these birds were females. The number of adults was quite stable across years. The total population of Kea in this area was estimated to be between 88 and 119, or in the order of 0.018 to 0.040 birds per hectare. Mortality did not exceed 16-20% per year for adult and subadult birds, but it was probably higher for younger birds. Male juveniles all appeared to disperse from the area within the first two years; female juveniles, on the other hand, were frequently resighted in subsequent seasons. This difference in behaviour was statistically significant. The abundance of fledglings suggested that as few as 10% of adult males may breed in any given year.