The Blackpoll Warbler (Setophaga striata) is a small songbird that breeds across Canada and the northeastern United States. But where do these tiny birds go when they migrate away from their breeding grounds each fall?
The Blackpoll Warbler undertakes one of the most incredible migrations in the avian world. Each fall, after breeding and raising young in the boreal forests of North America, Blackpoll Warblers fly non-stop over the Atlantic Ocean to their wintering grounds in South America. This feat is made even more impressive by the Blackpoll’s small size – at just 12 grams, it is truly a tiny bird. Their migration covers thousands of kilometers over a few days, an astonishing journey for such a small creature.
So where exactly do Blackpoll Warblers go in the winter? Researchers have uncovered that these birds take different migration routes depending on where they breed, but they ultimately end up in northern South America. Here are the key facts about their migration and wintering grounds:
Fall Migration Route
In the fall, Blackpoll Warblers take different southbound routes depending on their breeding origin:
- Birds from Alaska migrate down the west coast of North America before crossing over Mexico and Central America.
- Birds from western Canada migrate over the Great Plains and Gulf Coast region.
- Birds from eastern Canada and the northeastern U.S. migrate along the Atlantic coast.
However, regardless of their starting point, most Blackpoll Warblers converge on the northeastern United States in September. This region acts as a jumping off point for their transoceanic journey across the Atlantic to South America.
Specifically, Blackpolls gather along the coasts of Maine, New York, and Massachusetts as they prepare to depart over the open ocean.
Transoceanic Flight
The Blackpoll Warbler’s transatlantic crossing is one of the most spectacular migrations in the bird world. They fly non-stop over 2000-2700 km of open ocean to reach their final destination. This journey takes about 72 hours, an astonishing feat of endurance!
Experts estimate that Blackpolls make this incredible transoceanic flight by riding fast-moving air currents high in the sky. They soar up to 10,000 feet in altitude to locate favorable tailwinds that can propel them over the ocean.
Some key facts about their transatlantic crossing:
- Depart from the Northeast U.S. between late September and early October
- Fly over 2000-2700 km non-stop over the Atlantic
- Journey takes around 72 hours of continuous flight
- Fly at altitudes up to 10,000 feet to locate tailwinds
- Mortality rate for the transoceanic crossing may be around 50%
Successfully making landfall in South America after this grueling transatlantic journey is a major accomplishment for such a tiny songbird. Those that survive will join others that opted to take different overland routes to the wintering grounds.
Wintering Grounds in South America
The Blackpoll Warbler winters entirely in northern and central South America. Their wintering range includes:
- Venezuela
- Colombia
- Ecuador
- Peru
- Bolivia
- Brazil
They are most abundant in Colombia and Venezuela. Within these regions, Blackpolls inhabit tropical forests, woodlands, and shrublands up to about 2000 meters in elevation. The highest density of wintering Blackpolls occurs in moist montane forests.
Tropical Forest Habitats
On their South American wintering grounds, the habitats that Blackpoll Warblers occupy include:
- Tropical montane cloud forests – dense, wet, mossy forests at middle elevations in the Andes Mountains.
- Tropical lowland rainforests – diverse forests rich with plant and animal life.
- Tropical deciduous forests – drier forests that lose their leaves during the dry season.
- Second growth forests – regenerating forests recovering from disturbance.
- Woodlands and shrublands – open areas with scattered trees and shrubs.
These tropical ecosystems provide the food and resources that Blackpoll Warblers need to survive the winter months. The fruits and insects of the tropics offer a bounty that fuels the birds for their long migration back north in spring.
Spring Migration Back to Breeding Grounds
The Blackpoll Warbler’s spring migration back to its breeding range in Canada and the northeastern U.S. is not as direct as in fall. Rather than flying back over the ocean, Blackpolls opt for routes over Central America and Mexico to return north.
There are a few key stopover sites and routes used by Blackpolls in spring:
- Some birds follow Andean mountain passes north through Colombia and Venezuela.
- Many birds stopover in Costa Rica and Panama before traversing Mexico.
- Coastal routes through Central America are also used.
- Birds spread out across the Gulf of Mexico region before fanning out across the continental interior.
By May, Blackpoll Warblers have returned back to their breeding grounds in the boreal forests of Canada and Alaska. Here the cycle begins again, with males arriving first to establish territories before females return to build nests and raise the next generation of migratory Blackpoll Warblers.
Conclusion
The Blackpoll Warbler’s yearly journey is an amazing round-trip migration spanning thousands of kilometers. After breeding in the boreal forests of North America, they fly long distances over ocean and land to winter in South America’s forests. Their ability to undertake this strenuous annual migration and survive the immense challenges along the way make the Blackpoll Warbler one of the avian world’s elite long-distance migrants. Careful habitat conservation along their migration routes and in both their breeding and wintering grounds is crucial to ensuring this tiny bird’s epic migration continues long into the future.