In 1932, fewer than 70 trumpeters were known to exist worldwide, at a location near Yellowstone National Park. This led to the establishment of Red Rock Lakes National Wildlife Refuge in 1935. Red Rock Lakes is located in Montana's Centennial Valley and is part of the Greater Yellowstone ecosystem. Nearly half of the known trumpeter swans in 1932 were found in this area. Warm springs provide year-round open waters where swans find food and cover even in the coldest weather.
Today, estimates show about 46,225 trumpeter swans reside in North America, including some 26,790 in the Pacific Coast population (Alaska,Yukon, and NW British Columbia) which winter on the Pacific Coast; 8,950 in Canada; about 9,809 in the Midwest; and about 487 in the tri-state area of Idaho, Wyoming, and Montana (including the Red Rock Lakes refuge flock).