The population size, breeding, and annual cycle of Antarctic terns (Sterna vittata bethunei) at the subantarctic Snares Islands were studied intermittently from 1976 to 2002. During the 1983/84 and 1984/85 breeding seasons the population comprised a minimum of 65 breeding pairs. Laying dates extended from mid Sep to late Mar, with peak laying in late Oct-early Nov. Clutch size averaged 1.33 (range 1-2 eggs) and did not change through the breeding season. Both parents incubated. Hatching success was 92.7% and both parents fed the young. Fledging success was 75%, and so overall breeding success was 69.6%. Chicks were fed mostly fish by both parents and 1-chick broods were fed smaller fish and less frequently than 2-chick broods. The youngest bird recorded breeding was at least 3 years old. After the breeding season (from Mar), the terns formed flocks and moulted in the vicinity of the Snares Islands. Following the completion of moult (from Apr) they tended to move offshore, only returning to the shelter of the islands during severe weather. From mid Jul, the terns tended to roost in flocks at the Snares Islands before dispersing to form pairs and defend nesting sites.
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.