Surfing the Storm

When it comes to long-distance travel, bats are taking their cues from birds and riding the storm.

A new study from the Max Planck Institute of Animal Behavior discovered that noctule bats coordinate their spring migrations across Europe by surfing warm storm fronts to save energy.

Researchers did this by tracking for three years the journeys of 71 female bats flying from northeast Switzerland to destinations such as Germany and Poland.

They used ultra-lightweight, intelligent tags to obtain detailed information, including the animal’s activity and surrounding air temperature, which was then transmitted via a novel long-range network.

“The sensor data (is) amazing!” lead author Edward Hurme said in a statement. “We don’t just see the path that bats took, we also see what they experienced in the environment as they migrated.”

Hurme and his colleagues observed that the animals traveled up to 238 miles in a single night – far surpassing previous records – and did so in a hopping pattern, which means they alternated long flights with rest stops, to eat.

The team also noticed a peculiar behavior on certain nights that Hurme described as “an explosion of departures that looked like bat fireworks.”

When they analyzed weather data, they found that the bats migrated en masse ahead of approaching storm fronts, reported Smithsonian Magazine.

The bats used warm tailwinds from these storm fronts to conserve energy during their flights – a behavior previously observed only in birds.

The tags’ sensors confirmed that bats expended less energy while “surfing” storm fronts, taking advantage of environmental wind conditions to power their long-haul flights.

“This was actually a big surprise,” said Hurme. “We had some clue that bats were responding to good wind conditions, but we didn’t think that there was this connection to storms.”

The authors explained that understanding these migration patterns can help in conservation.

Bats face significant threats from wind turbines and predicting these patterns could help wind farms reduce their activity on high-risk nights.