Swans worldwide are a small family of seven species. Minnesota sees three of those each year (probably).
We see resident trumpeter swans, migrating tundra swans and invasive mute swans. (The migrating tundra swans will be arriving shortly.)
Trumpeter swans are here because of an extraordinarily successful reintroduction program. Native to the state, these birds were extirpated throughout the Lower 48 states during settlement days, hunted for food and sport, habitat put to the plow.
There is now a growing population in Minnesota alone of nearly 30,000 birds scattered between our borders with Canada and Iowa. The Twin Cities area has dozens of nesting pairs.
Reintroduction was started and managed by the DNR in the early 1980s. The Three Rivers Park District also had a program.
We see the second species, tundra swans, in migration, spring and fall. They nest in northwestern Canada and winter in Chesapeake Bay along the Atlantic. Draw that flight path and you cross Minnesota.
With very good luck you can see a long V of tundra swans overhead, alerted to their presence by the faint whoo whooing calls drifting down from the flock. I think those few rare moments if you catch them are the best Minnesota offers in fall birding.
The third swan here is the mute, a nonnative species kept by some waterfowl fanciers, and subject to occasional escape. When possible, mutes are recaptured by the Department of Natural Resources. Mutes are European birds introduced in North America to fancy-up waterfowl collections. They are environmentally destructive.