Brant

A rather small member of the Goose family, they breed in the high Arctic tundra. Winters along both coasts. 

When they migrate, they fly across great areas of land or open ocean, flying at altitudes several thousand feet high!

The Brants that visit the Pacific Coast have black bellies, while the ones along the Atlantic Coast have gray bellies and at one time they were considered separate species, but not anymore. Often you can find differences in the coloring of the same species in various parts of the world.