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The foraging behaviour of the South Island robin

Notornis, 28 (2), 89-102

Powlesland, R.G. (1981)

Article Type: Paper

The foraging behaviour of the South Island Robin (Petroica australis australis) was studied at Kowhai Bush, Kaikoura, from August 1976 to July 1978. Robins spent 90% of their foraging time on and within two metres of the ground. They spent 61.3% of their foraging time gleaning on the ground, 33.8% scanning, 4.5% gleaning amongst vegetation, 0.3% hawking and 0.1% flycatching. The proportion of foraging time devoted to the various foraging methods differed between adult and immature robins. The diurnal patterns of ground gleaning, scanning and above-ground gleaning for adults in the breeding and non-breeding seasons, and for immatures in the non-breeding season are described. Most foraging time was spent searching (93.7%), the rest killing, dismembering and eating prey. Robins relied largely on sight to find prey, but also seemed to stimulate prey movement by foot-trembling and tail- and wing-flicking. Most movements of foraging robins were hops and steps (88%), the rest being flights. About 8% of foraging time was spent flying. The robin’s diet consisted of invertebrates, except in summer and autumn when some berries were taken.

Size variation in the snow petrel (Pagodroma nivea)

Notornis, 28 (3), 169-188

Cowan, A.N. (1981)

Article Type: Paper

During a year spent at Casey, Antarctica, in 1977-1978, I made a study of the local population of the Snow Petrel (Pagodroma nivea). The breeding distribution of the species in the area is outlined, together with some of the problems encountered. The Snow Petrel varies widely in size. The literature on the species is reviewed. Large birds (wing over 280 mm) are known chiefly from Dumont d’urville, Adelie Land. Other published occurrences of large birds have often gone unnoticed or have been disregarded. Large birds breed at the Windmill Islands, making up 35% of 178 birds measured. Most of these large birds are concentrated in one area and some show the same atypical choice of “open” nests as at Dumont d’urville. Some large and small birds interbreed. These findings are discussed, and the hypothesis of separate “large” and “small” subspecies is critically examined. It is concluded that the species has great individual variation in size, and that large birds form a varying proportion of the populations breeding at many localities.

Black-fronted terns wintering in the Bay of Plenty

Notornis, 28 (4), 221-239

Latham, P.C.M. (1981)

Article Type: Paper

The habits, feeding and plumage variations of the Black-fronted Tern (Sterna albostriata) were studied during their April to August wintering period in the Bay of Plenty, from 1977 to 1981. Their migration to and from, and occurrence in, the North Island is discussed. The possibility of numbers visiting the Bay of Plenty being on the decline is raised. The study of the plumage variations led to the conclusion that two age-groups are present and readily recognisabIe during their entire stay in the Bay of Plenty and a third is recognisable for at least 3 months of the wintering period. The extent of time over which the autumn-winter moult of the adult takes place is discussed.

A study of the Gentoo Penguin Pygoscelis papua

Notornis, 28 (3), 189-202

Reilly, P.N., Kerle, J.A. (1981)

Article Type: Paper

Gentoo Penguins (Pygoscelis papua) were studied for 3 months at four separate colonies on Macquarie Island. No external characters were found for sexing and ageing adult birds, but first-year birds could be distinguished by plumage. Breeding success varied between colonies from an estimated 0.36 to 1.14 chicks per pair. Chicks joined creches by 5 weeks cf age, and they were fully feathered by 11 weeks, when the mean weight was 5.4 kg. An unusual temporary partial retention of body feathers by moulting adults was observed, and a weight loss of 3.3% per day during moult was similar to that of other penguin species.
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