On the way West, Lewis saw and heard swans overhead. These could have been trumpeter swans which nest in North Dakota. Trumpeter swans, with a seven-foot wingspan that makes them the world's largest waterfowl, were too prominent and showy to make it through the late-19th-century fashion craze that demanded exotic feathers for hats. But with the help of the Red Rocks Lake National Wildlife Refuge near Yellowstone National Park, the population rebounded from fewer than 50 in the Lower 48 in the 1930s to near 4,000 today.

State species of concern.