In northern Quebec, egg laying began in the first week of June; hatching occurred in the second and third weeks of July (Savard and Lamothe, 1991, Can. Field-Nat. 105:488-496). Clutch size is 5-8 (often 8). Incubation lasts 27-28 days (Terres 1980). Young are tended by female, independent in 6-7 weeks (Harrison 1978).
Comments: No precise estimates available, but minimum numbers are at least 500,000 individuals in western Europe in winter (early 1970's) and 500,000 individuals in North America, with additional large numbers in eastern Asia (Madge and Burn 1988).
Comments: Except in inland habitats, mollusks comprise a majority of the diet; the blue mussel (MYTILUS EDULIS) often is a major food (Bellrose 1976). Also eats crustaceans, some fishes and plant foods, the latter being most important in inland habitats. Usually feeds in protected areas where water is no more than 25 ft deep.
Non-Migrant: No. All populations of this species make significant seasonal migrations.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.
Comments: Mostly coastal waters, less commonly on large inland lakes and rivers when not breeding. Nests near lakes and pools on grassy or bushy tundra and in northern taiga (AOU 1983). Usually nests close to water. The nest is a depression lined with plant material, down and feathers.