Trumpeter swans are the largest native waterfowl species in North America. These graceful birds stand nearly 5 feet tall, with wingspans over 7 feet wide. Their all-white plumage and long, straight necks make them unmistakable.
Trumpeter swans breed during the summer across parts of Alaska, Canada, and the northern United States. However, as winter approaches, freezing waters force trumpeter swans to migrate south to more temperate climates. Their winter grounds stretch from the Pacific Northwest south into California and east to the Midwest and along the Atlantic Coast.
Why Do Trumpeter Swans Migrate?
Trumpeter swans migrate to escape harsh winter conditions in their northern breeding grounds. Frozen lakes, ponds, and wetlands make finding food difficult for these large waterbirds during winter.
Trumpeter swans rely heavily on aquatic vegetation for food. They use their long necks to reach below the water’s surface and uproot plants from muddy bottoms. But when their habitat freezes over, trumpeter swans cannot reach this essential food source.
Migrating south allows trumpeter swans to follow spring as it advances and find newly thawed wetlands full of nutritious underwater plants. Spending winters further south prevents starvation and increases survival rates.
When Do Trumpeter Swans Migrate?
Most trumpeter swans begin migrating south in late September and October. Some individuals start moving earlier in September, while stragglers may wait until November or even December before migrating.
Spring migration north begins as early as late February for some pioneering individuals. Peak spring migration occurs March through May as trumpeter swans follow the retreating snow line and thawing wetlands to their northern breeding grounds.
The exact timing of migration varies by location, weather, and individual. Older, more experienced trumpeters often migrate earlier than younger birds. Extended wintry weather can also delay both fall and spring migration movements.
Where Do Trumpeter Swans Spend the Winter?
Trumpeter swans winter across a broad region of North America, shifted south from their core breeding range:
Pacific Coast and Northwest
Thousands of trumpeter swans from Alaska and western Canada migrate down the Pacific Coast into Washington, Oregon, and California. Central California’s Sacramento Valley provides vital winter wetland habitat. Further north, swans congregate in the Puget Sound region and along the Fraser River in southwest British Columbia.
Interior West
Many swans winter throughout the interior West from British Columbia down to Nevada and New Mexico. They frequent agricultural areas, lakes, rivers, and wetlands with open water. Large concentrations gather at Summer Lake Wildlife Area in south-central Oregon.
Midwest and Great Lakes
The Midwest and Great Lakes states host the majority of trumpeter swans in winter. They migrate south across the Great Plains from Canada and Alaska to winter on lakes, rivers, and farmlands. Particular hotspots include Illinois’ Mississippi River Valley and areas along the Missouri River.
Atlantic Coast
Smaller numbers of trumpeter swans migrate from their limited East Coast breeding areas to winter along the full length of the Atlantic seaboard. They frequent tidal marshes, bays, and estuaries from Maine to South Carolina. Chesapeake Bay and Currituck Sound in Virginia and North Carolina support thousands of wintering swans.
Interior Canada
Some trumpeter swans only migrate short distances within Canada’s interior to areas with open water. They congregate on streams, springs, power plant discharges, and other icy-free spots. Major wintering sites include the North Saskatchewan and Athabasca Rivers.
What Routes Do Trumpeter Swans Follow?
Trumpeter swans use well-established pathways during annual migrations between northern nesting areas and southern wintering grounds:
Pacific Flyway
This major migration corridor funnels swans down the west coast. It spans the Rocky Mountains, Great Basin, and Mojave Desert from Alaska to Mexico. Pacific Flyway trumpeter swans winter from British Columbia to California.
Central Flyway
The Central Flyway overlaps the Mississippi Flyway in the Great Plains and Midwest and directs swans along the spine of the Rockies. Trumpeters following this route winter from Alberta to Texas.
Mississippi Flyway
This is the most important trumpeter swan migration route. The Mississippi River and Central Flyway guide birds south from Canada’s Hudson Bay. The Mississippi Flyway accommodates up to 75% of migrating trumpeter swans ending up in the southern Midwest and Great Lakes states.
Atlantic Flyway
A smaller number of East Coast trumpeters migrate south via the Atlantic Flyway. This coastal route stretches down the entire Atlantic Seaboard.
What Threats Do Migrating Trumpeter Swans Face?
Trumpeter swans encounter many obstacles and dangers during biannual migrations:
Habitat Loss
Wetland drainage and destruction along migration paths and wintering grounds reduces food and shelter. Trumpeter swans require large, open aquatic habitats.
Lead Poisoning
Trumpeter swans ingest lead shotgun pellets and fishing tackle, poisoning themselves. Lead sinkers and jigs are especially dangerous when swallowed by foraging swans.
Collisions
Trumpeter swans collide with power lines and towers frequently during migration flights between wetlands. They also hit vehicles when crossing roads between water bodies.
Shooting
Some trumpeter swans are misidentified and accidentally shot by waterfowl hunters during the fall migration season.
Predators
Golden eagles, coyotes, bobcats and other predators seize trumpeter cygnets and occasionally adults during migration when the birds are more vulnerable.
How Many Trumpeter Swans Migrate?
An estimated 15,000-20,000 trumpeter swans make the migratory journey each fall and spring. The total population across North America numbers around 63,000 individuals.
About three-quarters of the global trumpeter swan population migrates seasonally between nesting and wintering grounds. The highest concentrations occur in the Mississippi and Central Flyways converging on the Great Lakes and Midwest.
Major Wintering Sites
Several key wintering sites host enormous flocks of migrating trumpeter swans each year:
Upper Mississippi River National Wildlife Refuge
Stretching 261 miles through four Midwestern states, the refuge attracts up to 3,700 trumpeter swans to open river waters and associated wetlands.
Chesapeake Bay
Maryland and Virginia’s Chesapeake Bay provides critical winter habitat for over 2,000 trumpeter swans in its estuaries and tidal marshes.
Central Valley, California
California’s fertile Central Valley attracts thousands of wintering trumpeter swans to its seasonal marshes and flooded agricultural fields.
Summer Lake Wildlife Area, Oregon
Oregon’s high desert marsh at Summer Lake hosts up to 1,000 trumpeter swans, representing around 10% of the Pacific population.
| Wintering Site | Estimated Swan Population |
|---|---|
| Upper Mississippi River National Wildlife Refuge | 3,700 |
| Chesapeake Bay | 2,000 |
| Central Valley, California | 3,000 |
| Summer Lake Wildlife Area, Oregon | 1,000 |
Conservation Efforts
Several initiatives seek to protect trumpeter swans during migration:
Habitat Protection
Federal and state agencies acquire and manage wetlands along flyways to provide habitat. Nonprofit groups also purchase and conserve wetlands through easements.
Lead Tackle Buybacks
Programs buy lead sinkers and jigs from anglers to reduce lead poisoning in swans. Maryland banned small lead tackle to protect trumpeter swans in 2021.
Supplemental Winter Feeding
When natural food runs short, some refuges and agencies feed swans agricultural grains and pellets to reduce starvation. Strict permitting regulates supplemental feeding.
Power Line Marking
Markers and diverters make power lines more visible to prevent deadly collisions. Some areas bury lines underground in key habitat.
Reintroductions
Releasing captive-raised trumpeter swans helps restored lost migratory populations and establish new wintering flocks across their former range.
Research and Tracking
Scientists study trumpeter swan migration patterns and behavior using several methods:
Leg Bands and Neck Collars
Marked birds help identify migration routes, winter sites, survival rates, and other data when re-spotted in the field. Unique codes allow long-distance tracking of individuals.
Satellite Transmitters
Affixing solar-powered GPS satellite transmitters to swans pinpoints locations in real time. Transmitters reveal precise migratory pathways and timing. However, devices are still too large for cygnets.
Stable Isotope Analysis
Isotopic signatures in swan feathers indicate origins and general wintering areas. Analyzing ratios in hydrogen, carbon, nitrogen and strontium isotopes reveals migratory connections between breeding and wintering grounds.
Genetic Analysis
DNA sampling helps map genetic structure among migration subpopulations. Analyzing genetic variation elucidates the degree of breeding ground connectivity and isolation.
Migration Challenges
Trumpeter swans face escalating migration obstacles from human impacts:
Wetland Drainage Intensifies
Expanding drainage ditches and tile networks destroy wetland habitats across flyways and wintering grounds. Wetland loss also increases following major hurricanes when floodwaters remain trapped behind levees.
Lead Poisoning Continues
Despite tackle buyback efforts, lead fishing gear persists in bottom sediments where swans feed and ingest lost tackle. More restrictions on small lead sinkers are needed to prevent poisoning.
Climate Change Threats Emerge
Warmer winters with less ice cover encourage more swans to overwinter northward and forgo migration. Milder conditions mean swans linger longer during spring migration and arrive earlier on nesting grounds before food peaks.
Collisions Increase
Expanding wind turbines, communications towers, utility lines and roadways intersect more migration pathways. Resulting collisions reduce survival for these slow-maneuvering birds.
Hunting Pressures Build
With swelling swan numbers redistributing northward during migration, more states allow limited swan hunting seasons, increasing accidental shooting of trumpeters.
Conservation Needs
Sustaining healthy trumpeter swan migrations requires strong conservation measures:
Wetland Restoration
Constructed wetlands should mimic natural designs with gentle slopes, irregular shapes, and native vegetation to attract swan use. Funding needs increase to restore drained wetland complexes across flyways.
Non-toxic Alternatives
Phasing out lead fishing gear reduces poisoning risk. Continued outreach helps anglers switch to non-toxic, affordable options like tungsten, tin, and bismuth jigs and sinkers.
Power Line Changes
Prioritizing underground lines or rerouting overhead lines away from wetlands protects flight paths. Diverters make remaining overhead wires more visible through wetland crossings.
Harvest Restrictions
With trumpeters mixing into tundra swan flocks during migration, suspending tundra swan hunting seasons may become necessary to protect recovering trumpeter populations where the two species’ ranges increasingly overlap.
Monitoring
Expanded tracking studies using satellite telemetry and stable isotope analysis provide finer-scale migratory data to enhance conservation. Comparisons reveal how migration timing and pathways evolve with climate and land use changes.
The Future of Trumpeter Swan Migration
The future of trumpeter swan migration faces uncertainties from expanding human alteration across flyways:
More Short-Distance Migration
Warmer winters likely increase short-distance migration as more trumpeters overwinter further north. However, reduced migration distances and tradition could imperil populations during extreme cold snaps.
Shifting Winter Distributions
Milder coastal winters may shift winter distributions eastward. However, reduction of agricultural grain supplies with altered crop patterns can redistribute swans westward into depleted grassland habitats.
New Migration Traditions
Reintroductions establish new migratory flocks. Yet new cohorts skip migration altogether, as evidenced by increasing year-round swan populations in the Chesapeake Bay and British Columbia Coast.
Weakened Migratory Connections
Fragmenting habitat, lead poisoning, and shifting climate weaken links between distant summer nesting and winter grounds. Isolated subpopulations lose migration traditions, undermining flyway resilience.
Altered Migration Timing
Earlier spring thaws likely prompt earlier migration north, reducing food supplies upon arrival. Milder falls delay southbound migration, narrowing preparation for winter. Mismatched timing imperils migration success.
Protecting migration corridors and winter habitat remains crucial for trumpeter swans despite uncertainties surrounding climate impacts. Maintaining connectivity between distant summer and winter sites sustains genetic mixing, tradition, and flexibility to help ensure the resilience of these iconic migrants.
Conclusion
Trumpeter swans make epic migratory journeys spanning thousands of miles annually between northern nesting grounds and more southerly wintering regions. These powerful fliers traverse the continent along Pacific, Central, Mississippi and Atlantic flyways in search of ice-free waters and vital wetland food resources.
Although threats exist from habitat loss, lead poisoning, collisions, and disturbance, trumpeter swan migrations persist, bolstered by conservation action. Ongoing research and tracking continues to reveal new insights into the comportment and ecology of these migratory birds. As landscapes and climates change, sustaining resilient migration corridors between distant summer and winter ranges remains key to ensuring the perpetuation of trumpeter swans across North America.
