Migrating Birds Fly Nonstop for 6 Months
The alpine swift glides and flaps throughout its entire migration across the Sahara Desert and sub-Saharan West Africa.
Scientists have long suspected that the Alpine swift -- a swallowlike bird that has a wingspan of about 22 inches (57 centimeters) and a body length of about 8 inches (20 cm) -- spends much of its life in flight, based on field observations and radar data collected during its migration. But, until now, researchers have not been able to prove just how long these birds fly without taking a rest.
Researchers at the Swiss Ornithological Institute and the Bern University of Applied Sciences in Burgdorf, Switzerland, have collected data showing that the birds take little to no breaks during their migration from breeding grounds in Switzerland to wintering grounds in Western Africa and back again the following year. The team details their findings today (Oct. 8) in the journal Nature Communications. (Quest for Survival: Incredible Animal Migrations.)
To collect their data, the researchers outfitted six birds with small tags that logged acceleration and ambient light during the course of a yearlong migration cycle that began and ended in Switzerland. Only three of the six birds were recaptured the following year, but these individuals provided enough data to complete the study, the researchers said.
The team analyzed the acceleration patterns captured by the loggers to determine when the birds vigorously flapped their wings, when they glided and when they rested.
The only period of sustained resting appeared during the breeding period in Switzerland. The birds appeared to glide and flap throughout their entire migration across the Sahara Desert and their overwintering period in sub-Saharan West Africa.
"Their activity pattern reveals that they can stay airborne continuously throughout their nonbreeding period in Africa and must be able to recover while airborne," the team writes in the report. "To date, such long-lasting locomotive activities had been reported only for animals living in the sea."
Migrating sea animals, including a variety of whale and fish species, expend less energy migrating than birds do because the swimmers rely partially on their own buoyancy to help keep them afloat.
Birds expend lots of energy during flight, but Alpine swifts do not need to stop to eatbecause they feed midair on what is called aerial plankton - the atmospheric equivalent to marine plankton that can include an array of tiny bacteria, fungus, seeds, spores and small insects that get caught in air currents.
Whether or not the birds sleep in flight remains unclear, though periods of decreased movement suggest that they do, indeed, catch up on a bit of rest midair. Still, the clear lack of significant resting periods suggest that the birds do not need as much sleep to perform their migration as previous research has suggested.
"We cannot rule out that the Alpine swifts may interrupt their flight for a few minutes," the team writes. "Nevertheless, they must be able to accomplish all vital physiological functions in flight over a period of several months."
The team next hopes to determine the evolutionary drivers responsible for what they consider to be an extraordinary behavior.
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The Alpine swift has the longest non-stop flight pattern known of in the avian world.
Oct. 5, 2012
- For the first time, all 39 known birds of paradise are documented in a single volume that reveals the beauty and unusual behavior of these unique birds, which evolved in remote and rugged parts of New Guinea, the Maluku Islands and eastern Australia. Co-author Edwin Scholes, an ornithologist at the Cornell Lab of Ornithology, told Discovery News, "The birds-of-paradise represent one of the most incredible examples of biodiversity on our planet and yet few people have ever heard about them or seen them because they are only found in the remote and difficult-to-reach forests of New Guinea and a few nearby areas." "Birds of Paradise: Revealing the World's Most Extraordinary Birds" (National Geographic Books) was co-authored with photographer Tim Laman and comes out later this month. The Raggiana bird-of-paradise, shown here, is "the quintessential bird-of-paradise of culture and myth in the eastern half of New Guinea," according to Scholes and Laman. Here a male performs a solo practice display in a small forest near a village in the Southern Highlands of Papua New Guinea.
Scholes said this male Wilson's bird-of-paradise is performing a courtship display "from a well-used sapling in the middle of his cleared display territory, or court, on Batanta island off the coast of western New Guinea. Males of this species are a riot of color, with brilliant blue skin and yellow, red, metallic blue and metallic green feathers."
This male twelve-wired bird-of-paradise is flapping his wings and calling in order to attract a female. Its name comes from the cluster of twisted wire-like feathers that protrude from bright yellow feathers covering the lower portion of the adult male's body.
This paradise riflebird resembles females from the same species, but his striking courtship display pose gives away his true colors. Scholes said he "will soon transition into strikingly different adult plumage." This bird was photographed in the mountains of D'Aguilar National Park near Brisbane, Australia.
Daybreak bathes this male red bird-of-paradise in a warm glow as he flutters his wings during part of his courtship display ritual. Laman said this image was snapped high above the rainforest canopy of Batanta Island, west of New Guinea. Other birds-of-paradise, such as lawes' parotia, have mirror ball-like structures that catch the light and achieve somewhat the same effect as a dance club mirror ball, but even more pronounced. We do not know of any man-made material that achieves the same effect," Daniel Osorio, a professor of Neuroscience at the University of Sussex, told Discovery News.
With their dancing and other dramatic moves, male birds-of-paradise tend to draw the most attention. Females, however, "call the shots during performances," Laman said. Here, a female greater bird-of-paradise studies one of two males in a tree-top area deep in the rainforests of the Aru Islands.
"Like a hidden jewel in the forest, the male king bird-of-paradise may be one of the smallest of the birds-of-paradise, but his colors and displays are rarely seen treasure to behold," according to Scholes. The bird was photographed in the forest canopy of a lowland forest of the Bird's Head Peninsula of western New Guinea.
Scholes and Laman say the bronze parotia was first described in the mid 19th century from a few poorly preserved museum specimens of unknown origins. It wasn't observed in the wild until 2005, when it was found living the remote and uninhabited Foja Mountains of northwestern New Guinea.
This brilliant metallic blue-green and orange male, splendid astrapia, is seen as he forages for schefflera fruit. "Found only in the high-elevation cloud forests of western New Guinea, this species is one of the least known of all the birds-of-paradise," Scholes said.
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"A wonder to behold, the male king of saxony bird-of-paradise has exceptionally long and plastic-like tabbed plumes on either side of his head," Scholes said. "These extraordinary feathers are so unlike any other feather known that early collectors believed they were fabrications created to garner a higher price in the plume trade markets!" The bad news for birds-of-paradise is that their ranges are extremely small, so the birds are vulnerable to even small amounts of habitat loss and forest degradation, the authors share. The good news, however, is "that their home in New Guinea and nearby islands includes the largest tracts of intact rainforest in the entire Asia-Pacific," Scholes said. He concluded, "To ensure that future generations are able get the same sense of awe and wonder that get today when seeing birds-of-paradise and their incredible displays in the wild, we need to continue to learn more about them and their unique forest habitats."
Tune into "Winged Planet," this Saturday, October 6 at 8 ET/7 Central and experience the astonishing physical wonders of our world from a bird's eye view.