A study of the sooty shearwater (Puffinus griseus) was made at the Snares Islands during four summers. The work is based partly on the activities of 31-45 marked pairs in burrows and partly on more general observations. These large, powerful shearwaters (weight 819 g) return in late September and, after a ‘scratching-out’ period of about a month, part of the population leaves on a prelaying exodus which lasts about two weeks. Laying reaches a peak from 20 to 24 November and incubation takes 53 days, most eggs hatching from 11 to 16 January. No precise nestling periods were obtained, but adults depart on migration from the end of March and most leave by the third week of April. Most chicks leave during the last weeks of April and the first week of May. Surface-laid eggs are plentiful. They tend to be smaller and narrower than burrow-laid ones and, on average, are laid three days later than those underground. During incubation the male takes the first stint on the egg after the female’s brief initial one. Thereafter the stints are of similar length, averaging about 9.4 days for both sexes. Samples of chick weights for their first 40 days are given as well as weights of 500 chicks at the time of banding just before their first flights. Flooding of burrows is the chief overt cause of chick mortality. Differences in timing of breeding at Whero Island and The Snares are discussed. In general, the timing seems to be similar throughout the birds’ range from Australasia to the Falklands and Tierra del Fuego, but precise information is very sparse.
Re-examination of the type material of Anomalopteryx oweni (Haast) indicates that this taxon should be synonymised with A. didiformis (Owen).
Fewer than 50 adult spotless crakes (Porzana tabuensis) plus 24 chicks and four juveniles were found on Aorangi in February and March 1980. They were confined to the valley and preferred a low mixed forest which is being replaced by a less favoured habitat. Habitat preference is discussed and related to changes in numbers in the past. Clutch size is lower than on the mainland and chick production probably lower. The breeding cycle is long. Some observations on the adult-chick relationship are presented.
By means of data in the literature and a large sample of sexed birds from Signy Island, South Orkney Islands, snow petrels (Pagodroma nivea) are shown to be sexually dimorphic in size and especially in body weight and bill length. By these characters alone, over 80% of Signy birds can be correctly sexed. It is suggested that the true status of the so-called large and small forms of the species can best be resolved by comparing birds of known sex and status. The sexual dimorphism in weight in snow petrels is amongst the greatest in the Procellariiformes and might relate to the extensive use of vocalisations in individual and sex recognition.
In November 1980, two Leach’s storm petrels of the typical subspecies (Oceanodroma leucorhoa leucorhoa) were discovered on Rabbit Island, Chatham Islands (44°14′ S, 176°16′ W), engaged in prebreeding activity. They were captured, examined, photographed, banded and released. The flight calling of one was recorded on tape. Their nocturnal activity continued until observations ceased. A subsequent check indicated that no chick was reared. Possibly they were of the same sex, and possibly there were only two. This is the first record of prospecting for nest sites in the Southern Hemisphere by this strictly Northern Hemisphere breeding species.
The food and feeding behaviour of the southern crested grebe (Podiceps cristatus australis) were studied on the Ashburton lakes (South Island, New Zealand) in 1979 and 1980. Of 47 food items eaten on the surface by adults, 55.5% were fish, 31.9% were insects and 12.6% were plants. Chicks in their first week ate mainly fish under 55 mm long. Both adults and chicks ate feathers. One pellet contained feather, fish, insect, plant and egg remains. Dives lasted on average 20-30 seconds. Feeding success of adults was high while they were feeding chicks. The New Zealand and European subspecies are compared. Differences suggest that much less food is available in New Zealand, which may affect productivity and population size.
Diurnal roosts of black-billed gulls (Larus bulleri) were found at 37% of inland foraging sites during the breeding season. Roosts were most common and commuting between colony and foraging groups least common far (>5 km) from the colony. Selective use of roosts far from the colony is energetically efficient and may help to maintain local population densities at levels sufficient to permit efficient search for food by means of local enhancement.