The trumpeter swan was once nearly extinct. In 1932 there were fewer than 70 of the birds worldwide.
But they've made a remarkable comeback.
The US Fish and Wildlife Service says today there are 16,000 trumpeter swans in North America.
One major winter gathering spot for trumpeter swans is on the Mississippi River in central Minnesota.
Warm water discharged from the the Monticello nuclear power plant keeps the river free of ice, and as many as 1,500 of the birds gather in one spot at a time.
Minnesota Public Radio's Tim Post stopped by the site recently and found well-known Minnesota photographer Jim Brandenburg taking in the noisy scene.