Fast-flying bats rely on late-night refreshments to reach great heights

Although scientists knew that some bats could reach more than 1,600 meters (or about a mile) above the ground in flight, they did not understand how they could have done without it. The advantage of thermals is that they are not usually available during the forums during the night. Now, researchers report in the journal Conventional biology on February 4th they have discovered the mystery of bats flying high.

It turns out that the European free-tailed bats they studied – powerful leaflets that the researchers recorded sometimes reach speeds of up to 135 kilometers (84 miles) per hour in a plane self-power – depends on orographic elevation that occurs when air is pushed up over rising ground to help them fly high, just like birds during the day. However, as that is harder to find during the colder night, they have to rely on just the right types to reach those high altitudes.

“We show that wind and topography can predict areas of the landscape that can support high altitudes, and that bats use these areas to reach high altitudes during their lifespan. reducing airfields, “explained Teague O’Mara (@teague_o), of the University of Southeastern Louisiana. and the Max Planck Institute for Animal Behavior.” Bats then weave a wind position to guide high climbs, which making use of direct wind energy in the night scene. “

To find these traces, O’Mara and colleagues placed the free-tailed bats with high-resolution GPS recorders that recorded their location in a three-dimensional space every 30 seconds, tracking them for up. to three days overnight of about six hours. The data show that bats emerge immediately after sunset and fly all night before returning to fare.

They observed that bats’ flights usually followed the ground they were crossing, but sometimes climbed very high, reaching nearly a mile above ground level. ground in less than 20 minutes. During these high altitudes, the bats would climb faster, longer, and at a lower plane than they would climb more moderately to about 300 meters. Most bats landed quickly after reaching their highest altitude, resulting in a sort of rollercoaster flight path.

The researchers were amazed to find out exactly what was expected to be the high altitude of bat flight across the country. The data show that bats use the same types of places – although they may not always be the exact places – where the wind sweeps up a slope to carry them to higher altitudes.

“We were ready to see that these bats were flying fast, so that was no surprise to us,” O’Mara said. “But the fast, attractive, wind-powered trips were something our team weren’t looking for or preparing for. “

The results show that bats solve flight problems in bird-like ways – just at night, the researchers note.

“These free-tailed bats seem to be finding ways to use the energy they need to find food every night,” said O’Mara. believable for an animal that can only see in detail the 30 to 50 meters ahead. It takes a lot of energy to go up to 1,600 meters above the ground, and these bats have found a way to cycle as the wind rises. ”

While the researchers already had a pretty good idea based on past work that the bats could fly surprisingly fast, they say that this ability to fly fast is still “a problem. unresolved. “

“Their small body sizes and large, flexible wings covered with a thin ball were adopted to prevent these fast distances,” O’Mara said. “But it’s now clear that bats can fly incredibly fast when they pick up. It’s up to us to figure out how they do that and whether it can be applied to other situations,” such as high-speed engineering and low-energy engineering. fly.

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This work was supported by Deutsche Forschungsgemeinschaft under the German Strategy for Excellence, the Fundação para a Ciência ea Tecnologia, Portugal, and the Chair of Biodiversity Energias de Portugal.

Conventional Biology, O’Mara et al .: “Bats use terrain and nocturnal refreshments to fly high and fast” https://www.cell.com/current-biology/fulltext/S0960-9822 ( 20) 31894-7

Conventional biology (@CurrentBiology), published by Cell Press, is a bi-monthly journal of papers across all fields of biology. Conventional biology seeks to encourage communication across the fields of biology, both by publishing important findings of common interest and through a face-to-face topic accessible to non-experts. Visit: http: // www.cells.com /conventional biology. To receive Cell Press media alerts, contact [email protected].