Publications Archive

A study of habitat selection and feeding behaviour of brown teal (Anas castanea chlorotis) was conducted on Great Barrier Island from 7 to 14 February 1973. In the Port Fitzroy area, teal fed almost exclusively in the tidal estuaries. Feeding was tide-regulated. and foods seemed to be invertebrates selected on a declining tide. During high tide, teal usually roosted in the shade of trees. At several sites on the eastern part of the island, teal fed in slow-moving freshwater streams or brackish lagoons. In addition to dabbling and upending, teal dived regularly and efficiently. By a creek at Whangapoua Beach, most of 112 teal fed in the uplands either by probing in grass or by grabbing insect larvae from forbs. Teal also fed in the uplands at night. Brown teal are very adaptable in feeding sites and fill the niche of both aquatic dabbler and ground-feeder. They are most abundant in estuarine situations, and the survival of the species depends upon protection of suitable habitats. Intensive human use of estuaries on the mainland probably is responsible for the drastic decline of the species.

The grey heron (Ardea cinerea) was placed on the Suspense List of the 1970 OSNZ Checklist, as the Checklist Committee could not confirm the existence of an 1898 specimen reported by Buller. Buller’s “third collection,” including this heron, is in Carnegie Museum of Natural History, Pittsburgh, Pennsylvania, U.S.A. The grey heron should be readmitted to the main New Zealand list, but under the name A. c. jouyi Clark rather than A. c. rectirostris Gould.

Features of plumage and behaviour of the soft-plumaged petrel are described and compared with those of other species of Pterodroma, especially P. inexpectata, and Procellaria cinerea, as an aid for further reports of the species at sea.

The occurrence of a white-winged triller (Lalage sueurii) at Macandrew Bay, Otago Peninsula, in February 1969, is documented, being the first record of this species for New Zealand.

The variable oystercatcher (Haematopus unicolor), which has melanistic, pied and intermediate phases, was studied in the field in New Zealand from 1969 to 1972 inclusive. Parents and their progeny were colour-banded, and the development of plumage with age was checked for non-genetic variation. The parent-offspring data can be most simply explained by a genetic model involving a major gene (W) whose dominance is modified only in the heterozygous condition. In the model, the pied condition is homozygous dominant (WW), the melanistic condition is homozygous recessive (ww), and all intermediate-plumaged birds are heterozygous Ww. The wide range of plumage variability in the intermediate phase seems most likely explained by the action of polygenic modifiers acting cumulatively at a number of loci, and specifically on the Ww genotype. Gene frequencies and genotype frequencies are in Hardy-Weinberg equilibrium, indicating that selection does not operate against the heterozygote to form an isolating mechanism between the homozygous pied and melanistic phases. The three phenotypes are therefore best considered as colour phases of one species, H. unicolor.