"Man's interest in consuming , as well as in using their feathers for warmth and their fat for lighting and heating, was behind their early domestication. Two goose species were involved, the and the , and two ducks, the and the . Features of all wildfowl domestication include large size, a reduced number of tail and wing feathers, flightlessness, rapid maturation, an increased clutch size, long breeding season, loss of 'broodiness' (so that the technique of artificial incubation becomes necessary at an early stage), loss of aggression, a polygamous mating system, and the laying down of abdominal fat."