The Blackpoll Warbler: Tiny Bird, Amazing Migrator

Monarch butterflies spend generations migrating across the entire North American continent, and humpback whales log as many as 3,000 miles a month as they go between Alaska and Hawaii. But as impressive as they are, these charismatic critters have nothing on the Blackpoll Warbler—an unassuming bird with one of the most ambitious migration routes on the planet.

In the fall, this warbler may not be much to look at—its striking bright white-and-black pattern is dulled by the olives, grays, and yellows that make up its fall and winter plumage. The bird is also lighter than an empty soda can—an average adult weighs in at just 12 grams. But new research confirms that these small creatures undertake one of the longest and most impressive migrations of the animal kingdom.

A Very Long Migration

The diminutive warblers breed in the boreal forests of North America before heading to northern South America for the winter—a familiar migration path. But these birds take migrating to an extreme: Once they leave their breeding areas, they fly continuously for three days straight over the Atlantic Ocean before having a chance to stop in Colombia or Venezuela, a non-stop feat that was only confirmed last spring thanks to the miniaturization of tracking technology. To make the trek, the birds pack on the pounds—errr, make that grams—nearly doubling their fat stores before their non-stop flight.

Most of the excitement over these birds focused on the over-water portion of the journey. But researchers just confirmed that the blackpolls’ migration is even more impressive than a three-day sprint across the ocean implies.

While some blackpolls breed in the northeast (in Vermont, or Nova Scotia, for example), others breed as far west (and north) as Alaska. And when they take off for the winter, they don’t cut any corners—in fact, they do the opposite. These hardy birds fly clear across the continent before turning right to head south along with their East Coast-breeding counterparts—making this among the longest migrations, ounce for ounce, for any bird out there.

We know how this little bird migrates thanks to 50 years of bird banding data. With more than 25 years of experience banding thousands of migrating birds at various stations, Canisius College biologist Sara Morris was in the perfect position to combine, reformat, and analyse data on 22,295 individual warblers compiled from 13 banding stations. That allowed them to confirm that the western-breeding birds indeed fly all the way to the east coast before continuing on to the south, adding thousands of miles to their already-epic quest.

Making Sure The Blackpoll Makes It

She and her colleagues also discovered that over the past half century, the birds have started their migration around one day earlier per decade, perhaps owing to the effects of climate change on the changing seasons. The birds to the West may be even worse off—since they have to travel east first, their breeding period may be even shorter.

“Migration is a really complicated event,” Morris says, noting that birds need ideal habitat to be able to properly prepare. “Birds have to increase their food intake to prepare for this arduous journey.”

Despite the continental scale of the migration, what the warblers really need is local conservation efforts to keep food reserves bountiful. To keep this member of the least-protected group of birds strong, Morris suggests that homeowners landscape with native plants, which will provide the right food sources.

It’s important to make sure these birds can keep making the trek, says biologist Barbara Frei, a postdoc at the University of Ottawa. Disrupting the birds’ ability to head south could have reverberating ramifications for the ecosystems where they winter—for example, it could throw off the tropical forests’ insect communities.

It may not be as well-known as a monarch butterfly or as huge as a humpback whale, but the humble little Blackpoll Warbler surely deserves to keep its place among the world’s most epic migrants—as long as the planet continues to support it.

Editor's note: This story has been updated to reflect the fact that the new research is a synthesis of information that confirms the Blackpoll Warbler's long trek. It has also been modified to more accurately detail the bird's appearance.