Apart from the negative PR they received in the aftermath of coronavirus pandemic, bats are genuinely fascinating creatures. They rule the night skies and can fly as high as 1,600 meters (over 5,000 feet). But how do they do it? Scientists have wondered for a long time how some bats manage to fly this high especially at night with no warmth of the sun to support their flight. It might have something to do with their speed and their surrounding wind, new study suggests.
“We show that wind and topography can predict areas of the landscape able to support high-altitude ascents, and that bats use these locations to reach high altitudes while reducing airspeeds,” said Teague O’Mara, author of the study published in Current Biology.By integrating wind conditions to high altitude ascents, bats can exploit vertical wind energy in the nocturnal landscape.
Scientistsstudied European free-tailed bats that are capable of reaching up to 135 kilometres/hour speed. Their flight is something Scitech Daily describe as “self-powered.” They depend on orographic uplift (of or originating from mountains or height) which occurs when air pushes up against a rising terrain. Regular birds can do this during the day easily enough but bats have to stick to very particular areas in the cool night air to reach such heights.
To analyse these areas, the team used bats with GPS trackers which relayed their location in 3-dimensional space, every 30 seconds, all through their night flight. They emerged right after sunset every night and flew constantly till dawn or their return home.They observed that high-altitude ascents were faster and longer while the air speed was lower. They compared the flight to a roller-coaster as their descent after peak-height is very rapid. They also discovered that these ascents were predictable in the landscape. They use the same kind of places where the wind sweeps up a slope to carry them to high altitudes.
O’Mara noted it takes a lot of energy to fly such heights at night. He said this is a pretty incredible challenge for an animal like bat as it can only perceive the 30 to 50 meters ahead of it. though he knows how they reach such heights, he still cannot confirm why or how they fly so fast.If that mystery is resolved, it can have applications in fields like engineering bio-inspired high-speed and low-energy flight, says O’Mara.