Do Blackpolls Sleep in Flight Over the Atlantic?

Blackpoll warbler in PA, Oct 2020 (photo from Wikimedia Commons)

5 October 2023

Some birds are champion fliers, staying airborne for days or months at a time. Scientists wondered if birds sleep in flight and proved that they do in a 2016 study of great frigatebirds, finding that the birds either “sleep with one half of their brains active, or with both hemispheres shut down at the same time.” Read more in this vintage article, Asleep in Flight.

Blackpoll warblers (Setophaga striata) are also champion fliers making a non-stop fall migration over the Atlantic Ocean of 1,900 miles in 72 to 88 hours. Traveling at 27 mph, they launch from the east coast between Nova Scotia and South Carolina and fly to their only stopover in Puerto Rico or Hispaniola (Haiti & Dominican Republic), then on to northern South America.

The blackpoll’s transoceanic path was proven in a 2015 study by Bill DeLuca and the Vermont Center for Ecostudies. VCE writes:

Bill DeLuca (Northeast Climate Science Center) and VCE solved this great modern-day avian mystery. Using light-level geolocators attached to Blackpoll Warblers in Vermont and Nova Scotia, DeLuca and colleagues documented the longest distance non-stop overwater flights ever recorded for a migratory songbird. During October, Blackpoll Warblers initiate a ~3-day non-stop transoceanic flight of ~2500 km from the north Atlantic Coast to Hispaniola and Puerto Rico. Radar data show migrating songbirds fly at 2,600 to 20,000 feet while making this journey. After a few weeks, they fly onto Columbia or Venezuela where they overwinter. Their spring migration route takes them over Cuba to Florida, where they journey up the eastern US seaboard to reach their breeding grounds in late May.

Vermont Center for Ecostudies: Blackpoll Warbler

Notice in this eBird abundance map for the week of 2 Nov that blackpolls are:

  • bunched up on the East Coast from Massachusetts to North Carolina
  • at a stopover on Puerto Rico and
  • early migrants have already arrived in South America.
Blackpoll warbler weekly abundance map, week of 2 Nov 2007-2021 (map from eBird Status and Trends)

Watch them throughout the year in this eBird abundance animation.

Blackpoll warbler weekly abundance map (animation from eBird Status and Trends)

Of course I wondered if blackpoll warblers sleep in flight during their 3 day transoceanic trip, but we won’t find out any time soon. Blackpolls are way too small to wear the sleep monitoring gear used on the great frigatebird.

(photo from Wikimedia Commons, maps from eBird Weekly Abundance; click on the captions to see the originals)

ebird species migration weekly abundance trends

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