Breeds on Arctic tundra. Locally common in winter, in agricultural areas, prairies or marshland, sometimes in flocks of 10,000's. Large skeins often fill the sky and lead you to where birds are feeding. In large flocks, most birds appear white, often with a few darker birds (juvs and blue morphs) mixed in. Flocks are compact with 'lookouts' at the edges. When flushed, they take off in unison with a loud din - one of the great bird spectacles. ID: Medium-sized with heavy body and sloping head with large bill. Striking dark 'grin patch,' where mandibles meet, enhances 'mean' impression. Noisy. Sexes similar. 2 morphs: White outnumber Blue 100:1 in E, 40:1 in Mississippi river valley. White morph: Juv: variably dingy gray; Ad: white with black wingtips. Often has yellow on head and neck (never in ROGO). Blue morph: Juv: variably dingy dark gray-blue; Ad: gray-blue with white head, white extending onto neck. Intermediates occur. Occasionally hybridizes with ROGO, when all features are intermediate.