Recent estimates of the number of yellow-eyed penguin (Megadyptes antipodes) throughout its range have led to a revised figure for the total population of this species. The number of breeding pairs on Stewart and Codfish Is together with the Auckland Is remain the least well known. Ground searches in 1984 -1994 on Stewart and Codfish Is suggested fewer birds than expected. The results of 102 ground searches of 61 localities and 118 beach counts (>700 h of observations) support a lowering of earlier estimates to c. 170-320 pairs on Stewart Is and its outliers, and 50-80 breeding pairs on Codfish Is, giving a total of 220-400 pairs for this region. The relatively few breeding pairs found on Stewart Is, based on the length of coastline and hinterland area available, together with the small groupings, suggest that predation of adults and chicks may be a factor in the relatively low numbers of this species on Stewart Is itself.
Moutohora (Whale Island) holds the largest surveyed breeding colony of grey-faced petrels (Pterodroma macroptera gouldi). For our estimate of the breeding population, we divided the island into 16 sections within which burrow densities were approximately uniform; the surface areas of these sections were found by planimetry. Apparently completed burrows were counted in 1998-2000 within each section by plots of 2 m radius along linear transects, or by 10 X 10 m contiguous plots. The total estimate (± SE) for the island was 109,000 ± 10,000 burrows, which equates to about 95,000 pairs breeding annually, given an occupancy rate of about 87%. The population has apparently more than doubled since Norway rats (Rattus norvegicus) and rabbits (Oryctolagus cuniculus) were eradicated in 1985/87.
Hunters of the endemic imperial pigeon (Ducula goliath) or notou in the Forêt Plate site, New Caledonia, in Apr 2001 and Mar 2002, allowed us to collect some biological material, measurements and descriptions from 63 pigeons. The sample included 5 immature imperial pigeons, and 58 adults. Several measurements of adult birds differed significantly between the sexes: weight, body length, wing length, tail length, tarsus length, and head length and width being greater in males (n = 28) than females (n = 30). A cross-validated classification using a discriminant function analysis on these variables allowed 74 % of the birds to be correctly classified as male or female. None of the qualitative characters (colour of skin, bill, iris, feet, feathers) was different between the sexes. Sexing birds using a bio-molecular analysis proved to be 100% reliable. The small gonads and the thin wall of the midgut indicated that the notou were not breeding at the time of collection. They had completed, or almost so, their wing moult. Fruits of 22 tree species and the leaves of trees and ferns were identified in material taken from digestive tracts. No internal parasites and few external parasites – of a low pathogenicity – were recorded. These results improve knowledge of this endemic species and should be useful in this popular game bird’s conservation and management.
Mainland colonies of Australasian gannet (Morus serrator) colonies at Muriwai, northwestem Auckland, New Zealand, were counted between 1999 and 2002. Fences installed in 1981 on the landward side of the colonies were removed at the end of the breeding seasons of 1996 (southern colony) and 1997 (northern colony). Counts 3 years before and after fence removal were compared. After fence removal, the total average number of birds during the peak breeding season (December and January) increased by 65%. The increase resulted largely from an increase in the average number of pairs nesting on the northern colony, and a small increase in the average maximum number of chicks on the northern and southern colonies.
Cook’s petrel (Pterodroma cookii), a New Zealand endemic, now breeds on only three islands at the extremities of its former range. Holocene fossil bones have indicated sites of 11 extinct colonies on North and South Islands, showing that Cook’s petrels preferred hills Gallirallus australis) have endangered these last colonies. Breeding success, most affected by rat predation of eggs and chicks, deteriorated seriously after extermination of feral cats from Hauturu, but improved significantly after eradication of rats from Whenua Hou. Rats are now a major threat on Hauturu. Cook’s petrels should be considered for reintroduction to suitable mainland reserves, to enhance biodiversity and restore nutrient inflows.
The taxonomic status of the endangered orange-fronted parakeet (Cyanoramphus malherbi)) has been the subject of much debate since this endemic New Zealand parakeet was first described in 1857. The debate in the late 1800s and again over the past 30 years has been lively but inconclusive. We provide a summary of this debate and the most recent research into the taxonomic status of this parakeet based on mitochondrial DNA (mtDNA), assortative pairing, bill morphology, vocalisation, and comparative ecology. Based on all available scientific and historical data, we conclude that the orange-fronted parakeet is a distinct species.
Little is known of the causes of mortality in captive-bred brown teal (Anas chlorotis) released to the wild. To test whether feeding difficulties have contributed to the poor survival of released birds, we developed a method to detect starvation using the wing fat content of brown teal. We extracted the lipids from 4 outer wing components of 17 intact brown teal carcasses. The lipid content of each component reflected the birds’ nutritional condition (based on body mass and size, and visible fat). Lipids were also extracted from the outer wing components of 7 partial brown teal carcasses, 6 of which were from captive-bred released birds whose cause of death could not be determined. All of the released teal were found to have been in very poor nutritional condition immediately before death, implicating starvation as a factor in their deaths. Improving the feeding regime of captive-bred brown teal (pre- and post-release) is likely to increase their survival.