Across their huge, circumpolar range, Dunlin have evolved into about nine subspecies. Ornithologists debate the number that occur in North America. Many scientists say one species breeds here, others recognize two or three. Genetic studies indicate two races exist, Pacific Dunlin breeding in western and northern Alaska, and Hudsonian Dunlin across Northern Canada. These breeding birds differ in size (Canadian birds being the largest), their backs’ brightness and their undertail covert’s streaking.
Pacific Dunlin winter from southern Alaska south along the Pacific Coast at least through Mexico. Hudsonian Dunlin winter along the Gulf Coast and eastern Mexico south South America (although the race of Latin American birds is often not determined (Warnock and Gill 1996). Based solely on range, the bird in this post is probably a Pacific Dunlin, since this photo was taken at Westport, Washington, along a Pacific beach.