Tundra swans take two pathways to Ӱ

Ned Rozell
907-474-7468
April 24, 2025

A man in a yellow raincoat, blue gloves, a ballcap and safety glasses holds a white swan inside a net enclosure with green grass in the background.
Photo by Donna Dewhurst
Biologist Craig Ely bands a tundra swan in the Yukon Delta National Wildlife Refuge in 2020.

Tundra swans — at 15 pounds and with a wingspan of almost six feet — are now touching down on the ponds and snowfields of Ӱ.

Not too long ago, Ӱ scientists discovered more about where the birds are returning from. 

Emeritus biologist Craig Ely of the U.S. Geological Survey Science Center in Anchorage was part of a team that captured and released more than 500 tundra swans in 2007 and 2008. 

The birds were temporarily flightless as they shed old feathers and grew new ones in their favorite Ӱ breeding areas: Cold Bay, King Salmon, the Yukon and Kuskokwim river deltas, Kotzebue Sound and the Colville River delta.

Ely handled many of those swans and helped to implant satellite transmitters in the abdomens of 50 birds. Those transmitters lasted for a few years, enabling scientists to confirm a split in Ӱ tundra swan populations.

Two swans fly through a blue sky.
Photo by Craig Ely
Tundra swans fly over western Ӱ.

Swans that spend their summers in tundra lakes north of the Brooks Range are East Coast birds in the winter, settling in Maryland, Virginia and North Carolina.

Swans that breed south of the Brooks Range in the wetlands of western Ӱ are West Coast birds in the winter, feeding in farm fields of Washington, Oregon and the central valley of California.

Though the East Coast and West Coast swans migrate wingtip to wingtip and pause in similar barley fields and lakes in Saskatchewan, the birds almost never follow their neighbors to a new place.

A pair of white swan cygnets rest on eggs in a nest.
Photo by Craig Ely
Newly hatched tundra swans, called cygnets, rest in a nest in western Ӱ.

“Tundra swans are extremely site faithful, so only extremely rarely would a Colville River bird end up on the West Coast,” Ely said.

Both the East and West Coast tundra swans spend the majority of their lives migrating. Unlike other birds now flying direct paths to Ӱ, tundra swans take months to cross the continent.

“All the Ӱ populations of tundra swans spend more time in migration than on breeding or wintering areas," Ely said. "They truly are birds on the move.”

Two maps of North America, one representing autumn and the other spring, feature yellow, red and blue lines to represent the migration pathways of tundra swans.
Graphic by Craig Ely
Birds marked with satellite transmitters revealed these autumn and spring migratory pathways for Arctic coastal plain (blue), Bristol Bay lowland (orange), and lower Ӱ Peninsula (red) populations of Ӱ tundra swans from 2008 through 2011.

Ely and other scientists think that the East Coast-wintering birds that summer on the Colville River may be flying an ancient ice-free corridor that could have been the only unfrozen pathway north during the last ice age.

Fascinated by the unique, divergent paths of the two populations of tundra swans, Ely and others studied which group, including lower Ӱ Peninsula tundra swans that don't migrate, might have a survival advantage. They found all swans were doing well despite how far they traveled and how little time that might give them on the breeding grounds.

“The tremendous diversity of migration strategies we identify in Ӱn tundra swans, without clear impacts on survival, underscores the ability of this species to adapt to different environments and climatic regimes,” Ely wrote.

Since the late 1970s, the University of Ӱ Fairbanks' Geophysical Institute has provided this column free in cooperation with the Ӱ research community. Ned Rozell is a science writer for the Geophysical Institute. A version of this story appeared in 2017.