Before and during a hurricane, meteorologists often show radar images of the storm’s vertical swirls. Colors added to the images enhance the ominous look of vortices, which are actually eddies in the atmosphere.
When scientists zoomed in on images of Hurricanes Matthew and Irma, they were shocked by what many showed: flocks of seabirds flying for their lives in each storm’s eye.
This storm survival strategy — one of many for birds — suggests that at least some bird species know when a hurricane is on its way, and have a good chance of successfully navigating through it with little to no visual cues in the apparent chaos.
New research published in the journal Science Advances finds not only that birds possess an “internal GPS system” that helps to guide these and other movements, but also that a model based on this system could be used to improve weather forecasting technologies.
Lead author Yusuke Goto of the University of Tokyo’s Atmosphere and Ocean Research Institute and colleagues Ken Yoda and Katsufumi Sato used what is known as the “inverse problem approach” to make their determinations. The approach comes from physics, a branch of science that Goto majored in before becoming interested in animal migrations and related data from biologging.
“In physics, the inverse problem approach is a widely used method for estimating variables that cannot directly be observed,” Goto told Seeker. “For example, astronomers can find out the temperature of a star, what the star is made of, and so on, just by investigating the light from the distant star.”
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He figured that, like astronomers, animal ecologists could estimate important, yet unmeasurable, variables by applying the inverse problem approach to large data sets of animal movements. In this case, the latter were data sets for streaked shearwaters, which are seabirds that migrate over long distances to waters off New Guinea, northern Australia, and the South China Sea.
The researchers recorded one location per minute of homing tracks for 33 of these birds to examine what their responses were in flight. The asymmetry of the seabirds’ positions along their flight path allowed the scientists to estimate the wind speed, wind direction, and heading direction.
He and his team were also able to estimate each bird’s orientation in flight, or how the shearwaters adjusted their heading depending on the intended goal direction, wind speed, and wind direction.
The authors wrote that their results “suggest the high cognitive ability of seabirds” to solve problems related to the many challenges that they face when flying over the open ocean.
In addition to such smarts, the researchers believe that the birds possess an inherent “map sense,” which they define as “the ability to know where one is on the earth and the distance and direction to one’s destination without any landmarks.”
This internal GPS system does not always require visual cues, Goto said. Prior research found at least some birds can hear infrasound and are sensitive to barometric pressure. Still other studies have shown the crucial role that olfactory cues play during seabird flights.
Humans possess a certain amount of map sense, and Goto said Inuit and Bedouin populations have keen inherent navigation abilities honed by experience.
“But their mechanism may be different from that of animals,” he said.
Blind individuals may also develop enhanced skills at echolocation, a technique often associated with bats that involves making clicking sounds to help understand the surrounding environment.
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In the future, Goto and his team hope to apply the inverse problem approach to various other animals for which large tracking data sets exist. For example, he believes that the method could be applied to marine animal movements, providing a more detailed look at how different marine species respond to current and wind changes.
The findings could benefit animal conservation efforts by revealing the energy cost of travel associated with climate change for particular species. The results could then be compared to population data over the same period, thereby showing any increases or declines.
“I think our method can also contribute to meteorology,” Goto said, explaining that detailed wind and climate information could likely be revealed by applying the approach to data sets pertaining to buoys, weather stations, and weather satellites.
While it is doubtful that human ability to predict storms will soon fully match the impressive skill seen in birds, Goto believes that the new research at least “may help to increase the accuracy of weather forecasts.”
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