Weight changes and wing moult in the Red-billed Teal

Abstract

The male Red-billed Teal Anas erythrorhyncha is longer-winged and heavier than the female but the data overlap. At Lochinvar National Park in Zambia, mean weight, reserves of abdominal fat and population size were minimal in February, during the breeding season (though none bred locally), and greatest between June and September, during the post-nuptial moult. In the moult of 1973 females probably lost 21% of their pre-moult weight, but males only 11%. It is suggested that weight loss is normally adaptive and not due to stress and allows birds to fly before the growth of the remiges is completed.