It may only weigh the same as a few teaspoons of sugar, but the blackpoll warbler is proving you don’t have to be big to be bold. This intrepid songbird migrates each fall from eastern Canada towards South America, but it doesn’t take this colossal journey at a leisurely pace. Far from it, in fact. According to a new study, this teeny, unassuming bird travels more than 1,500 miles (2,400 kilometers) over the Atlantic Ocean, non-stop, in just a few days. Details of this remarkable flight have been published in Biology Letters.
Migratory birds have a habit of continually astounding scientists by showcasing their seemingly impossible endurance skills. Around a decade ago, the longest recorded non-stop flight was just over 3,000 miles (5,000 km), but that was recently smashed by the current record-holder: The Alaskan bar-tailed godwit. These athletes travel an awe-inspiring distance of almost 7,000 miles (11,000 km) each fall, from Alaska to New Zealand, without a single pit stop to refuel.
While the blackpoll warbler doesn’t come close to matching this in terms of distance, if we take into account its body scale and size, it is arguably a chart-topper. Weighing a meager 12 grams, with a wingspan of just 20 centimeters, it is a fraction of the size of the bar-tailed godwit that weighs in at around half a kilogram (1.1 lb) and has a wingspan of close to a meter (3.3 ft).
But it’s taken a while for the blackpoll to receive the recognition it deserves. While its size may make its feat more impressive, it has also prevented scientists from being able to accurately track it. Until recently, geolocator tools used for this purpose have been far too bulky to affix onto the tiny animal, but as technology advanced, scientists were able to miniaturize the devices to a size sufficiently small for the job.
Armed with these dime-sized tools, researchers from the University of Massachusetts Amherst set out to investigate whether the blackpoll flies non-stop or indirectly from its starting point, New England and eastern Canada, to the Caribbean before completing the final leg and landing in South America.
The scientists fitted a total of 40 birds, 20 from Vermont and 20 from Nova Scotia, with the half-gram geolocator devices and then waited patiently for their return the following spring. They managed to recapture three birds in the U.S. and two in Canada, and the resulting data collected demonstrated that the animals do indeed migrate directly over the Atlantic. Over a period of just two or three days, the blackpolls travelled between 1,410 to 1,721 miles (2,270 to 2,770 km), stopping somewhere in Puerto Rico or Cuba before setting off again and making touchdown in Venezuela and Colombia.
To make this remarkable journey, the birds pile on the pounds before taking to the skies, eating as many insects as they possibly can. Some birds actually double their body mass in fat before the perilous “fly-or-die” journey so that they don’t need to stop for food or water. But why do these animals choose the hard route over an easier, albeit longer, coastal journey adopted by other migratory birds? It’s unclear, but it could be because shorter journeys reduce the risk of predation or hitting bad weather along the way.