Comments: BREEDING: Lakes, rivers, marshes and ponds in grasslands, barrens, dry tundra, open boreal forest or cultivated fields. Most breeding associated with seasonal and semipermanent wetlands (Suchy and Anderson 1987). Often nests near freshwater lakes and ponds, but may nest some distance from water. Readily uses stock-watering ponds in North Dakota (Suchy and Anderson 1987); uses all sorts of man-made ponds in Quebec (Belanger and Couture 1989). May nest under cover of low vegetation or in open. Broods use emergent vegetation for escape cover. Nest is a depression lined with plant material and down. NON-BREEDING: In migration and winter in both fresh-water and brackish situations (AOU 1983); prefers shallow, open freshwater lagoons, marshes, and slough in Costa Rica (Stiles and Skutch 1989).