Publications Archive

A severe and unseasonable snow-storm In South Canterbury in November 1967 killed many skylarks, yellowhammers, magpies, thrushes and blackbirds. A total of 810 dead birds, nearly all introduced passerines, were picked up in homestead gardens and around farm buildings during a three-day visit to the area two weeks after the storm began; no dead birds were found in native forest. Several runholders reported severe mortality to wild ducklings and goslings, though adult ducks and geese survived well. Most passerines resumed breeding soon after the snow melted, but yellowhammers and fantails remained extremely rare.

The evidence collected during a ten-year banding study of keas is considered. It is concluded that starvation is the most important cause of death.

Previous observations on Pycroft’s petrel (Pterodroma pycrofti) are summarized and distribution of the species is discussed. There are no records north of New Zealand, nor any to the south of the breeding-grounds. The nesting habitat is described, especially with reference to the apparent preference of Pycroft’s petrel for pohutukawa (Metrosideros excelsa) forest. Eggs are laid during the last week of November and the first week of December, with a peak on 26 November. Incubation is commenced by the male. Repeated desertion is discussed, with shortage of food reserves as a possible cause. Incubating birds lose 3–4 gm. per day. The mean weight for the species is 159 gm. On the breeding grounds eighty-one per cent of the population are unemployed birds. The proportion of unemployed birds in other petrel populations is discussed. The activity of breeding birds is compared to that of unemployed birds. Unemployed birds are responsible for calls heard over the colony in the air, most breeding birds arriving inconspicuously. The unemployed population may exert a social stimulus on the breeding birds. In the Appendix, individual burrows are described. Frequent reference has been made to the literature on petrel behaviour and ecology, and work on some important aspects is reviewed.

On six surveys of Swain’s Island in 1966 and 1967, field workers of the Smithsonian Institution’s Pacific Ocean Biological Survey Program recorded 16 species of birds: 9 central Pacific seabirds, 5 Arctic shorebird migrants, and 2 migrants from the southwest Pacific. Three species of seabirds (brown noddy, black noddy, and white tern) breed on the island and a fourth (white-tailed tropicbird) probably does so. The other species of seabirds recorded from the island (sooty tern, black-naped tern, frigatebird sp., red-tailed tropicbird, and red-footed booby) probably occur on the island only as visitants. Three of the shorebirds (golden plover, ruddy turnstone, and wandering tattler) are common and regular migrants to the island; the other two species (bristle-thighed curlew, sanderling) occur much less frequently and in much smaller numbers. One of the two migrants from the southwest Pacific, the reef heron, is apparently of irregular or uncommon occurrence while the other, the New Zealand cuckoo, is present in small to moderate numbers throughout much of the year.