New study records tiny songbird’s fly-or-die long-distance flight
The blackpoll warbler, completes an astounding nonstop flight of about 2,270-2,770km in two to three days
New Delhi: Using solar geolocator backpacks that can be fixed on birds, scientists have found that a tiny songbird, the blackpoll warbler, completes an astounding nonstop “fly-or-die" flight of about 2,270-2,770km in a mere two to three days.
This is one of the longest nonstop overwater flights ever recorded by a songbird, the researchers said in their study published in the current issue of Biology Letters, a peer-reviewed scientific journal.
The birds begin their journey in the autumn from New England (US) and Eastern Canada to migrate to South America by flying over the Atlantic Ocean. After the long journey, the birds land in Puerto Rico, Cuba or the Greater Antilles islands, and then fly on to northern Venezuela and Columbia.
“For small songbirds, we are only just now beginning to understand the migratory routes that connect temperate breeding grounds to tropical wintering areas," said first author Bill DeLuca, an environmental conservation research fellow at the University of Massachusetts (UMass) Amherst. “This finally confirms what has long been believed to be one of the most extraordinary migratory feats on the planet," DeLuca added in a release by UMass.
The authors explained why the flight was extraordinary—while there are other birds which have been known for their trans-oceanic flights, most migratory songbirds that spend their winters in South America take a less dangerous route that is interspersed by land through Mexico and Central America.
The flight of the warbler, which weighs only around 12gm, was hard to document earlier as the geolocators were too heavy for it, so only ground observations could be carried. But scientists developed new miniaturized geolocators weighing around 0.5gm that were fitted on the bird’s lower backs like a backpack.
These light-level geolocators use solar geolocation, a method that is based on the fact that the length of the daylight changes with latitude and that the time of the solar noon, which is the time of day at which the Sun’s rays are directed perpendicular to a given line of longitude, varies with longitude.
Since the earth takes 24 hours to rotate 360 degrees, the time at each longitude would vary by an hour.
The instruments record the date and length of daylight, from which daily locations can be assessed once the geolocator is traced. The authors of the study also outlined the migratory pattern from the geolocators.
Scientists had fitted geolocator packs on 20 birds in Vermont (US) and 20 more in Nova Scotia (Canada) out of which three birds from the Vermont group and two from the Nova Scotia group were retrieved for analyses.
The scientists observed that the birds eat as much as possible before beginning their journey, sometimes even doubling body weight as they do not eat or drink for days together. “For blackpolls, they don’t have the option of failing or coming up a bit short. It’s a fly-or-die journey that requires so much energy," said team leader Ryan Norris of the University of Guelph. “Of course, there is high mortality among migrating songbirds on such a long journey. We believe only about half return," Norris added.
DeLuca explained that many migratory songbirds, blackpolls included, are experiencing alarming population declines for a range of reasons, and that the scientists would like to understand more about how the birds spend time during non-breeding seasons to find out the reasons for the decline. Apart from UMass Amherst, the University of Guelph and the Vermont Center for Ecostudies, the Smithsonian Conservation Biology Institute, Acadia University, Bird Studies Canada and the University of Exeter contributed to funding the study.
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