Morphometrics of forest birds in the Orongorongo Valley, Wellington, New Zealand

Abstract

Birds in indigenous forest in the Orongorongo Valley, Wellington, were mist-netted from 1967 to 1976, and 3902 were weighed and measured. Average weight and measurements are given for New Zealand pigeon, shining cuckoo, long-tailed cuckoo, morepork, New Zealand kingfisher, rifleman, hedgesparrow, whitehead, grey warbler, fantail, tomtit, song thrush, blackbird, silvereye, bellbird, tui, and chaffinch. In 5 species males and females were easily identifiable by plumage differences, and also differed in size. Whiteheads were sometimes mis-sexed on the basis of head colour. Tui were not sexually dichromatic, but were strongly dimorphic, and were sexed by weight and wing length. Principal component analysis of measurements of tui and whitehead each produced 2 clusters of points that were assumed to represent males and females. The clusters for tui agreed with the identification derived from weight and wing length. Some Whiteheads classified as females from plumage were classified as males by principal component analysis; weights and measurements for male and female whiteheads identified by each method are presented. For dimorphic species, weights and measurements of adult males and adult females are given separately. Male riflemen were smaller than females, but in the other 6 dimorphic species males were larger than females.