Eggs, egg-laying and incubation in the Chestnut Teal

Abstract

Eggs, egg-laying and incubation were examined for Chestnut Teal Anus castanea using nest boxes in Victoria. The average egg measured 38.4 × 53.3 mm, and recently-laid eggs weighed about 44 g. Completed clutches averaged 10.1 eggs, and most eggs were laid at intervals of one day, but in larger clutches the average interval between eggs was lower and sug- gested that 'dump' egg-laying was taking place. Down generally appeared when about eight eggs had been laid. Losses of eggs throughout the study, attributed to avian predators, may have modified some results and certainly reduced pro- ductivity. Incubation averaged 26.6 days for the few eggs followed in the boxes, a result similar to the 25.8 days for eggs hatched artificially. Some aspects of 'dump' nesting are discussed in relation to the Chestnut Teal, a species that regularly uses artificial nest boxes.