Publications Archive

The previous distribution of the Shore Plover (Thinornis novaeseelandiae) and the possible reasons for its decline are outlined. The species is now confined to one small population on South East Island (Rangatira) in the Chatham Islands. In January and February 1993, we captured and banded or re-banded about 95% of this population and determined its age structure. Excluding juveniles of the 1992-93 season, 55% of the population is aged 6 years or less, 31% is aged between 7 and 12 years, and 14% is aged 13 years or more. The oldest bird currently alive is 18 years old. Estimates of population size and productivity for the season are compared with previous (mostly unpublished) records. Morphometric data are presented; there are small but significant differences in total head length, bill and tarsus between adult males and females, and in weight, wing and mid-toe between adults and 1-year-olds. In January, primary moult was more advanced in 1-year-olds than in adults.

A Kea (Nestor notabilis) is recorded as a fossil from the late Pleistocene of the North Island of New Zealand. Morphological and morphometric differences in osteology between the Kea and the Kaka (Nestor meridionalis) are described and discussed. Fossil and recent osteological specimens of the Kea and South Island Kaka have been confused in the past, resulting in Kea being identified as Kaka in collections and published lists. A fossil recorded as Nestor n. sp. in the Canterbury Museum is shown to be a South Island Kaka.

In 1990, as part of the Beach Patrol Scheme, 4,145 km of coast of New Zealand were patrolled and 7,145 dead seabirds found. An unusual find was a White Tern (Gygis alba). A summary is given of the coastal and monthly distributions of the eight Phalacrocorax, Leucocarbo and Stictocarbo species found during the 1943-1990 period. The Spotted Shag (Stictocarbo punctatus) was the most frequently found, mainly during February to June on Canterbury and Otago beaches.

Feeding observations of four species of Chatham Island endemic forest birds, Chatham Island Red-crowned Parakeet, Chatham Island Warbler, Chatham Island Tit and Chatham Island Tui, were collected on South East (Rangatira) Island in March and April 1990. The autumn foraging patterns of the forest species were very different. Parakeets had a broad omnivorous diet, Warbler and Tit were entirely insectivorous, and Tui fed mainly on fruit and some invertebrates. Parakeets used the widest variety of food plant species, including those from both forest and saltmeadow habitats. the Tui was the most plant-specific forager, with over 60% of feeding in one forest tree species. Because food availability changes throughout the year, other plant species will probably be important at different times. All birds fed at relatively low levels in the forest, often on the ground. This behaviour would make them particularly vulnerable to predation and may explain why the birds have now almost gone from other islands of the Chathams group.

The migration pattern for Cattle Egret in south-eastern Australia and New Zealand (Maddock 1990) is further clarified as a result of intensified observations of patagial-tagged birds and reporting of arrivals and departures of flocks by the observation network of Project Egret Watch in Australia and OSNZ in New Zealand since 1989. Seasonal outward migration from colonies in New South Wales after the breeding season to winter feeding ranges elsewhere in NSW, in Victoria and Tasmania, with return to the breeding colonies has been confirmed. Marked birds have been located in the same winter ranges, after having been recorded in the breeding colony for up to four consecutive years. Two cases of birds migrating to different locations in consecutive years have been recorded. The main movement is southward, but some birds migrate northward. The mean distance for southward migration is greater than for northward migration. Staging along southerly and northerly migration routes has been identified. The pattern of arrivals and departures in New Zealand identified by Heather (1978, 1982,1986) has been maintained, with tagged birds from Australia found in 1990 and 1991, but to date no marked birds have been located back in Australia after being seen in New Zealand. Birds tend to be restricted to highly localised ranges at the winter destination, using pasture on a single property or adjoining or closely related properties. Australian winter locations are generally restricted to coastal plains. Movements from the colonies take place in waves over a period of three months after the breeding period, although variation in dates from season to season has been identified. Birds tend to return to their natal colonies but some degree of colony exchange has been identified, particularly between neighbouring sites.

Details are given of the breeding phenology, breeding success and growth of chicks, obtained during the 1989/90 summer in a small population of South Polar Skuas nesting in the Larsemann Hills (69021°S, 76003°E), Princess Elizabeth Land, east Antarctica. Eggs were laid from mid-November to mid- December (mean date 30 November), chicks hatched from mid-December to early January (mean date 26 December) and fledged from 5 February onwards (mean date 16 February). Breeding success in the 13 regularly monitored nests averaged 0.5 chicks fledged per pair, i.e. 0.26 per egg laid. Asynchronous hatching resulted in most first chicks (from first eggs) dominating their siblings; they grew faster and survived better than the second chicks, presumably as the result of more food. Second eggs were significantly smaller than first eggs, and egg size and volume gave rise to slight differences in mass at hatching; this did not appear to influence chick growth. Food availability, unfavourable weather conditions and predation by other skuas were the main factors influencing chick growth and successful chick rearing; the presence of sibling aggression may have reduced survival in second chicks. Breeding success in the Larsemann Hills is considered in relation to foods available from feeding territories or from station refuse; in the small samples available, those pairs with obvious territories or with amore chicks to the flying stage.

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.