Publications Archive

We studied Pycroft’s petrel, Pterodroma pycrofti, at a breeding colony in the Hen and Chickens Islands, New Zealand, during the prebreeding and breeding seasons of 1982/83. Breeding birds attended their burrows singly and in pairs, often for several days at a time, from at least 38 days before laying, and up to 19 days before laying. No parents were in their burrows during the fortnight before laying, except a day or so before laying. In October/November the weights of breeders arriving at their burrows averaged about 150 g, but females arriving to lay weighed on average about 188 g, and males arriving to begin their first incubation stint averaged about 190 g – about 25% more than in October/November. The egg averaged 32 g. Daily weight loss over consecutive days in the burrow averaged 3.5-5 g/day, 2-3g of body weight. Laying took place from the second week in November to the end of the first week in December.  Egg dimensions are given. Incubation lasted about 45 days and the fledging period was 77-84 days.  Weights of fledglings ranged 156-188 g. From small samples, hatching success was 72% and fledging success 50%. Losses were caused by infertility, desertion and breakage resulting from fighting, probably with tuataras. One male failed breeder was at its burrow six weeks after its egg was broken. Non-breeders are defined as adults not known to breed in the current breeding season but may include some failed breeders. Some occurred in burrows in each observation period, and one was recorded throughout the study period, but more were at the colony in January than earlier. Non-breeders and breeders did not differ significantly in weight in October/November, but non-breeders did not usually achieve the higher weights of breeders arriving to lay or incubate. Weight loss of non-breeders in burrows was similar to that of breeders. The state of the brood patch, egg formation and the history of previously ringed birds are briefly discussed.

An annotated list of the 52 species of bird seen on and around the Noises Islands in Hauraki Gulf is presented, incorporating information from unpublished field notes from the 1930s onwards and the authors’ own observations, which began in 1977. Eight of the 20 species of seabird and 13 of the 32 species of land bird breed at the islands. The only breeding species of native forest bird are grey warblers, fantails and silvereyes. We review the breeding history of white-faced storm petrels and spotted shags. Analysis of Australasian harrier pellets showed that passerines were the most frequent prey and that carrion was taken from islands at least 2.3 km from the Noises. The contents of 13 blackbird and four song thrush gizzards were also analysed. Houpara (Pseudopanax lessonii) fruit was present in 12 blackbird gizzards and insects (mainly beetles) in eight. The thrushes had fed mainly on small snails and insects.

The 1980/81 distribution of the Australasian gannet (Sula serrator) in New Zealand is described and population changes since 1946 are examined. A brief history of the 26 breeding colonies and 23 roosts is given. Over 99% of gannets nested in the 23 colonies round the northern half of the North Island in 1980/81. Gannet roosts are mostly near the breeding colonies. The results of three national censuses taken since 1946 give an indication of the changes of the New Zealand gannet population in 34 years. The 1946/47 population was assessed at 21,115 pairs; 37,774 pairs were counted in 1969170 and 46,004 in 1980/81. The mean annual rate of increase for the whole population between 1946/47 and 1980/81 was 2.3%. In comparison with gannets in Australia, South Africa, and the North Atlantic, the gannet in New Zealand seems to be the only one steadily increasing and free from human interference.

During a study from January to June 1982, white-faced herons (Ardea novaehollandiae) visited the mudflats of Pauatahanui Inlet in greatest numbers in summer and declined after April as they dispersed to farmland. When foraging, they were essentially searchers, usually wading and walking, but occasionally standing and waiting for prey. They also used more active feeding methods, disturbing prey by foot-stirring, wing-flicking, and false striking with the bill, and pursuing prey by running, wing-flapping and hopping. How they captured and handled prey depended on the prey species. White-faced herons maintained variable individual distances using several agonistic displays, including forward and upright displays, chases, fights, and associated calls.

Early accounts of Little Barrier Island by Andreas Reischek emphasise that the stitchbird (Notiomystis cincta) was very rare there in the 1880s. Re-examination of the original accounts, in conjunction with dated specimens, suggests that the stitchbird was in fact very rare in 1880 and 1882 but increased markedly in 1883 and 1885. The rarity of the species on Little Barrier in 1880 and 1882 coincided with its extinction on the mainland and may have been due to introduced disease. However, several fluctuations in population size have taken place since. At least 78 and up to 130 of the 181 extant 19th-century specimens were taken by Reischek.