Mute Swan Distribution in North America

This map from the 2006 Great Backyard Bird Count does an excellent job of illustrating the current distribution of the introduced Mute Swan in North America. It has long-established strongholds in the Mid-Atlantic and in the Great Lakes, with an isolated small population in the Pacific Northwest. Though sizeable numbers (up to 1,000 birds was the last estimate I saw) have long been known from Florida, these are not considered to be established wild populations but rather semi-domesticated birds.