We sure have learned a lot about tiny Blackpoll Warbler recently.
First came irrefutable evidence, provided by the revolutionary tracking devices known as light-level geolocators, that the warbler flies nonstop over the Atlantic Ocean from New England and eastern Canada to South America each fall. The birds complete the journey in just two to three days.
The research was performed by a team led by Bill DeLuca, an environmental conservation research fellow at the University of Massachusetts Amherst, who characterized the bird’s marathon flight as “one of the longest nonstop overwater flights ever recorded for a songbird.”
Now, from a massive study being published in The Auk: Ornithological Advances, we learn that Blackpoll Warblers that breed in western North America make a longer journey than birds that breed in the east, since the western breeders have to fly east across the continent before migrating across the water.
Zoologist Sara Morris, a Fellow of the American Ornithologists’ Union and a professor of biology and associate vice president for academic affairs at Canisius College, in Buffalo, New York, was the lead author of the study.
When she and her colleagues analyzed data on 22,295 individual warblers banded in North America over the last four decades, they discovered that the western-breeding birds depart from their summer homes earlier than eastern-breeding birds do, leaving them a shorter amount of time each year to nest and raise their young.
The researchers also write that adult Blackpolls, which are more experienced than younger birds, travel more quickly across the continent and tend to be in better condition upon arrival, experiencing less mortality. The timing of fall migration has also been moving back by about a day each decade, report the authors, who speculate that the shift may be due to climate change.
“We tend to focus on Blackpoll Warbler’s transoceanic flight,” says Morris. “One of the things we hope people will think about as a result of this paper is that birds breeding in the west, particularly in the Northwest Territories or in Alaska, are also migrating all the way across the continent. They need tremendous resources in order to build the fat stores that are required for a successful flight.”
Her study, Morris adds, should serve as a reminder of the need to conserve habitats the warbler needs to rest and refuel while migrating.
Read the abstract
Sara R. Morris, Kristen M. Covino, Jason D. Jacobs, and Philip D. Taylor. 2016. Fall Migratory Patterns of the Blackpoll Warbler at a Continental Scale. The Auk: Ornithological Advances, Volume 133, pp. 41–51. Abstract.
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