The Status of Ducks (Anatidae) in the Darwin Area, Northern Territory, 1974-1986

Abstract

Twelve species of Anatidae were recorded during the study period 1974-1986 in the Darwin area, Northern Territory. Five species (Magpie Goose Anseranas semipalmata, Radjah Shelduck Tadorna radjah , Wandering Whistling-Duck Dendrocygna arcuata, Pacific Black Duck Anas superciliosa and Grey Teal Anas gibberifrons) showed significant and consistent seasonal patterns in their population sizes, with the first four species showing similar patterns. Radjah Shelduck and Wandering Whistling Duck have resident populations. Hardhead Aythya australis and Pink-eared Duck Malacorhynchus membranaceus did not show statistically significant seasonal patterns. Plumed Whistling-Duck Dendrocygna eytoni, Green Pygmy-Goose Nettapus pulchellus and Garganey Anas querquedula occurred irregularly, with levels too low to test for significance. Black Swan Cygnus atratus and Blue-billed Duck Oxyura australis were recorded only once; the latter was the first record for the Top End region. Population numbers showed considerable variation from year to year, however these variations were not correlated with the local rainfall patterns. Pink-eared Duck and Hardhead were first recorded in 1978 and 1976 respectively. Magpie Goose has shown a steady decline in numbers, which may perhaps be cyclical. Breeding records were obtained for three species, and all occurred during the late wet season (February-May).