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Kiwis and dog predation: observations in Waitangi State Forest

Notornis, 35 (3), 197-202

Taborsky, M. (1988)

Article Type: Paper

A wild dog was found to kill 13 out of 23 kiwis marked with transmitters. The whole population may have lost 500 out of 900 birds, although this estimate may be conservative. The population will probably need 10-20 years and a rigorous protection scheme to recover to previous densities.

Foraging by Adelie Penguins during the incubation period

Notornis, 35 (1), 15-23

Davis, L.S., Ward, G.D., Sadleir, R.M.F.S. (1988)

Article Type: Paper

Nine Adelie Penguins (Pygoscelis adeliae), 4 females and 5 males, were tracked by radio telemetry when they went to sea from the Northern Rookery, Cape Bird, Antarctica, on their first foraging trips of the incubation period. Each penguin took a different direction on leaving the rookery but maintained its approximate heading, suggesting that it was navigating. Radio contact was lost after 2-12 days as birds moved beyond the 100 km radio horizon. The penguins spent about one-third of their time on ice floes. Most of their time in the water was spent diving and feeding. Dives (including underwater swimming) lasted for a mean of 92.5 s , followed by a mean recovery period of 33.8 s. The length of the recovery period was significantly correlated with the length of the dive. From the maximum dive times, the duration of “feeding” dives, and the dive: pause ratios, Adelie Penguins seem to have diving abilities between those of the other two pygoscelid penguins, the Gentoo and Chinstrap. We hypothesize that the Adelie Penguins may travel large distances from the rookery during the incubation period so as to forage on the larger and more pelagic krill, Euphausia superba.

Changes in gull numbers over 25 years and notes on other birds of the Otaki-Ohau Coast

Notornis, 34 (4), 327-338

R.G. Powlesland, H.A. Robertson (1987)

Article Type: Paper

The number of Black-backed Gulls (Larus dominicanus) between the Otaki and Ohau Rivers, on the southwest coast of the North Island, has more than doubled in the last 25 years. There was a significantly larger proportion of subadults in 1961 than now, indicating that the population may have been in a growth phase in the early 1960s. The number of Red-billed Gulls (L. novaehollandiae) was about one-third of the 1961 level; this coincides with a sharp fall in the number of Red-billed Gulls nesting on nearby Kapiti Island. Numbers of other coastal birds were recorded and are discussed.

Genetics of polymorphism in the Little Shag

Notornis, 34 (1), 51-57

J.E. Dowding, M.J. Taylor (1987)

Article Type: Paper

A genetic model is presented to explain plumage polymorphism in the Little Shag (Phalacrocorax melanoleucos brevirostris). Parent-offspring data from an Auckland colony show that expression of the three morphs (white-throated, smudgy and pied) is primarily controlled by two alleles at a single genetic locus. The allele specifying ‘dark’ (D) shows incomplete dominance over that specifying ‘pied’ (6). Comparison of morph frequencies with calculated genotype frequencies reveals that about 40% of white-throated birds are homozygous dominant (DD), the rest of the white-throated birds and all smudgy birds are heterozygous (Dd), and pied birds are homozygous recessive (dd). The population mates non-assortively and the Hardy-Weinberg law correctly predicts the frequencies of black and pied offspring from crosses. Morph frequencies (and allele ratios) show a gradient from north to south in New Zealand, dark birds being more common in the south. The main factor maintaining this cline may be climatic.
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