These Trumpeter Swans above, some with neck collars, were photographed as they lifted up from the Wabash River near Montezuma, Indiana. Via their neck-collar numbers, they were traced to Wisconsin origins.
Tundra Swans closely resemble the somewhat larger Trumpeter Swan, and only a close inspection of their bill shapes and facial features, most notably the pattern of black and how it is patterned around the eyes, will clearly determine which swan is which.
Because Trumpeter Swans were hunted nearly to extinction, the Midwest sees almost all reintroduced birds, or descendants of those reintroduced birds. Because of the near-decimation of the Trumpeter Swan flocks, the world populations of Tundra Swans exceed those of the Trumpeters. Typically, however, Tundra Swans tend to be more shy and reclusive than Trumpeters.