The western population of tundra swans nests along the west coast of Alaska from Kotzebue Sound to the Alaska Peninsula. Major breeding concentrations are found on the Yukon-Kuskokwim Delta and in the Bristol Bay region. The western population of tundra swans has increased since the 1940s and has averaged about 60,000 since 1970. If one of the pair is lost, a new mate will be found before the next breeding season. Because of the lengthy development period for their young, swans begin nesting as early as spring thaw permits.
Trumpeters select a nest site typically in an undisturbed marsh adjacent to a small lake.
Tundra swans usually nest on elevated sites near large ponds or lakes that have emergent plant beds. Construction begins by uprooting nearby plants to form a nest mound that may be used year after year. When finished, a trumpeter nest is 6 to 12 feet in diameter and about 1 to 2 feet above water level with a ring of open water surrounding it. Tundra swans are also very territorial, but male and female tundra swans take turns incubating the eggs. During incubation, the cob begins a wing feather molt which leaves him flightless for about a month.