Across the Frozen Sky

As I laid out seed treats for wintering rodents–part of an ongoing capstone study on seed predation–a winter storm raged all around me.  Looking up, flurries of snow danced downward through the bare tree canopy around swaying tree branches in the freezing wind.  The sound of dry branches smacking and trees squealing as they rubbed against each other in the wind were the soundtrack for my hurried pace to keep warm and get out of the frigid and biting wind.

A flock of geese passed overhead, squawking against the wind.  I usually see or hear geese when I am here, likely a resident bunch that passes from crop field to crop field looking for scraps to scavenge.  A while later, I heard a different sound coming from the sky.  A soft, high-pitched ouoh ouoh sound rose from over the horizon to the North and then became louder and more distinct.  The chatter of a dozen or more tundra swans passing low over the forest filled the air and washed out the clashing and shrieking of the trees.  I heard the sound from my apartment a month before and darted out into the night, but missed any sight of them.  Now at least one flock passed directly overhead–pure white feathers against the grey winter sky.  With long necks outstretched and stroking the cold air with their wings each bird pressed on, and the V-formation of the flock sailed effortlessly out of sight.

Tundra swans, or whistling swans, are similar to most other North American swans in appearance: white feathers, a dark bill, and long neck.  Patches of yellow at the base of the bill help distinguish the tundra swan from the native trumpeter swan (with a solid black bill) and often domesticated mute swan (with an orange bill and black base).  The tundra swan’s call is much less nasal and harsh as the trumpeter swan.

Tundra swans breed in open sites across the northern edge of landmasses in the American and Eurasian Arctic.  In North America, flocks gather in large northern lakes after breeding and before embarking on a long autumnal migration across Canada.  Wintering grounds in the west include scattered large lakes, agricultural areas, and the Pacific coast.  In the east, the Great Lakes and, to a greater extent, the Chesapeake Bay regions are suitable wintering grounds.  In the winter, tundra swans feed on shellfish and grains from crop fields.  Before migrating north again in early spring, young tundra swans form mating pairs and older birds reinforce their lifelong bonds.

I marveled at the passing flock and their remarkable journey across the frozen sky.  It is inspiring to witness a few dozen creatures on their way from far-flung wild regions to the developed Atlantic coast.

While only a few months old, birds born and raised on the remote and ephemerally green tundra landscape must be ready for a migration of hundreds of miles or risk starvation and freezing.  Flying mostly in the cover of night, the swans pass over the Taiga–the great coniferous forest belt encircling the Arctic–and twinkling lights of inland cities and towns.  Their soft calls to each other are as much an encouraging cheer to press on as a distressed panting during their marathon flight.  The flocks that arrive in the Chesapeake Bay area spend their winter just offshore of the most heavily urbanized area in the United States.  Tundra swans thus connect the remote Arctic tundra to some of the most densely humanized landscapes on the planet with their migration.

Witnessing these impressive birds during their flight brings a sense of wildness to the tame eastern forests. Tundra swans’ incredible voyage is rooted in an enduring history of survival.  The nomadic lifestyle of many migratory animals–monarch butterflies, pronghorn antelope, and salmon–is only possible if stable habitats are maintained along their migration route and on breeding and wintering grounds.  For tundra swans, the isolated Arctic tundra and the urbanized coast are contrasting environments that the determined birds call home.

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