The Lesser Scaup (Aythya affinis) is a small diving duck.
Adults have a blue bill and yellow eyes. Adult males have a dark head with a purple sheen, a black breast, a light back, a black tail and a white bottom. Adult females have a white band at the base of the bill and a brown head and body. They are smaller than the Greater Scaup.
Their breeding habitat is marsh ponds in Alaska and western Canada. They nest in a sheltered location on the ground near water.
They migrate in flocks and winter in lakes, rivers and sheltered coastal waters along the west coast of North America, the southern United States and northern South America. They are more likely to be found on freshwater than Greater Scaup. These birds move south late in the fall and return in early spring.
They are a rare but apparently increasing vagrant to western Europe.
These birds dive and swim underwater, occasionally dabbling. They mainly eat mollusks and aquatic plants. It has been reported that this bird and the Greater Scaup have shifted their traditional migration routes to take advantage of the presence of Zebra mussels in Lake Erie. This may pose a risk to these birds because zebra mussels are efficient filter feeders and so accumulate environmental contaminants rapidly.
Lesser and Greater Scaup males are very difficult to distinguish in the field and females are almost impossible.
The purple gloss and subtle crest of the lesserscaup are visible in teh above photograph.
LesserScaup are common at the Sanctuary all year except in the summer when most have migrated inland to the interior of British Columbia, Alberta, or farther north to breed.
A scaup seen on a prairie slough in summer is almost certain to be a Lesser, and this species is also by far the commoner migrant in the prairie and parkland regions.
The LesserScaup is a much less common breeder in eastern Manitoba, but records extend east to Oak Hammock Marsh and the Lac du Bonnet region, and northward to Churchill; most nests in the south are initiated in June.
LesserScaup also appear at staging areas in southeastern Manitoba around September 20, building to a peak in mid- to late October, when flocks numbering in the thousands are not unusual.