A study of canvasback and redhead breeding populations, nesting habitats and productivity / David P. Olson

This study is an attempt to compare canvasback (Aythya valisineria) and redhead (Aythya americana) breeding populations and productivity on small prairie potholes, a large marsh, and a large shallow lake. The objectives are: 1) to record the changes in the sex and age composition and the size of canvasback and redhead breeding populations during the reproductive season; 2) to compare large and small habitats in relation to nesting and brood success; and 3) to investigate the interrelationships between canvasbacks and redheads attempting to nest on the same areas. The canvasback and redhead are diving ducks of the tribe Aythyini and both species are native only to the North American continent. They are quite similar in size, appearance and feeding behavior, but there is even more similarity in the habitats they use,particularly nesting habitat. Both species construct over-water nests in dense, emergent, aquatic plant cover. The canvasback tends to nest somewhat earlier than the redhea