The blackpoll warbler, a songbird that weighs no more than a ball-point pen, is a rather unassuming traveler. Flitting around boreal forests in Canada and the Northern US, these birds spend their winters in South America. Now, researchers have learned that they make that entire 1,500-mile trip without ever taking a break.
That's right, compared to this little warbler, the world's greatest triathletes, marathon runners, and even other birds are nothing but quitters.
According to Ryan Norris, a researcher for the University of Guelph, scientists have been debating for more than five decades whether or not blackpoll warblers (Setophaga striata) fly directly over the Atlantic Ocean to get to their wintering habitat. That's because field surveys in the past never stumbled across the bird heading south, despite the fact that it should have been there if it were taking a land-based route (making pit-stops to eat, etc.)
"The indirect evidence in favor of an Atlantic voyage was fairly strong," Norris said in a statement. "You have birds landing on ships in the Atlantic... and very few sightings of blackpolls in the southern US in the fall."
That's why Norris and his peers from Acadia University, Bird Studies Canada, the University of Massachusetts (UMass), the Vermont Centre for Ecostudies, and the Smithsonian Conservation Biology Institute, pooled their efforts to show that these birds were incredible ocean-crossing travelers once and for all.
The team outfitted several birds in Vermont and Nova Scotia with tiny 0.5 gram "backpacks" - geo-locators that tracked the bird's path as they flew.
When the bird returned in the spring, the research team quickly snatched up what devices they could and retrieved the data inside.
"When we accessed the locators, we saw the blackpolls' journey was indeed directly over the Atlantic," William DeLuca, of UMass, who led the Vermont part of the study, said. "The distances travelled ranged from 2,270 to 2,770 km... a tremendous voyage... with some likely flying from western Canada to the east coast before flying south."
This, the researcher added, can explain for why the birds seem to overeat right before they start their migration, sometimes becoming twice as fat as they normally are.
"For blackpolls, they don't have the option of failing or coming up a bit short," DeLuca explained. "It's a fly-or-die journey that requires so much energy."
The results were recently published in the journal Biology Letters.
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