Bats Ride the Storm: Mastering Wind Waves on Their Epic Migration

Bats, frequently overlooked in discussions about long-range migration, are beginning to gain recognition for their extraordinary travel abilities.

A recent investigation by scientists at the Max Planck Institute of Animal Behavior (MPI-AB) has offered unprecedented revelations regarding the migration tactics of common noctule bats.

By utilizing cutting-edge tracking technology, the researchers discovered that these diminutive mammals take advantage of storm fronts to enhance their energy efficiency throughout migration.

High-tech insights into bat behavior

“The sensor data is astounding!” proclaimed Edward Hurme, a postdoctoral researcher at MPI-AB and the Cluster of Excellence Collective Behavior at the University of Konstanz.

“We not only observe the route that bats followed, but we also learn what they encountered in the environment as they migrated. This context provides us with insights into the vital choices that bats made during their arduous and perilous journeys.”

The team utilized lightweight, smart tracking devices designed by MPI-AB engineers. These tags, which constituted merely five percent of the bats’ body weight, gathered extensive information, such as activity levels and air temperature, throughout the migration period.

The information was sent via a long-range network that offered coverage throughout Europe.

“The tags communicate with us from wherever the bats are because they benefit from coverage across Europe much like a mobile phone network,” detailed Timm Wild, who spearheaded the development of the ICARUS-TinyFoxBatt tag at MPI-AB.

Distinctive and variable bat migration routes

The study concentrated on 71 common noctule bats during their spring migration, which lasted for up to four weeks. In contrast to the predictable pathways often observed in bird migrations, the noctule bats adopted varied routes, even though all generally moved in a northeast direction.

“There is no single migration corridor,” remarked Dina Dechmann, a senior author from MPI-AB. “We previously assumed that bats were adhering to a fixed route, but we now discover they are traversing all across the landscape in a broad northeast direction.”

The research also indicated that noctules can cover nearly 400 kilometers in one night, setting a record for the species. However, their migration varies considerably from that of birds.

“Unlike migratory avians, bats do not gain weight in preparation for migration,” noted Dechmann. “They must refuel every night, resulting in their migration pattern being more of a hopping nature rather than a direct path.”

Syncing migration with weather

On certain nights, the researchers noted a significant surge in departures, which Hurme likened to “bat fireworks.” This prompted the team to explore the environmental triggers behind these occurrences.

They found that bats typically departed when air pressure dropped and temperatures increased – conditions related to impending storms.

“They were leveraging storm fronts, utilizing the advantage of warm tailwinds,” Hurme articulated. The tags also indicated that bats expended less energy on these nights, verifying that they utilize wind aid to propel their flights.

“It was already established that birds utilize wind support during migration, and now we observe that bats do as well,” he added.

Conservation implications

These discoveries have far-reaching consequences for bat conservation, especially concerning the dangers posed by wind turbines, a leading contributor to bat fatalities. “Prior to this study, we were unaware of what triggers bats to begin migrating,” stated Hurme.

He expressed hope that additional research could pave the way for systems that can predict bat migration. Such systems may assist wind farms in adjusting their operations to minimize collisions.

“We can act as stewards for bats, aiding wind farms in shutting down their turbines on nights when bats are migrating through. This is merely a small preview of what we may uncover if we continue to work towards illuminating that black box.”

Need for further research

Despite these advancements, much remains to be understood about the complete migration cycle of noctule bats, which encompasses approximately 1,600 kilometers each year. The study’s innovative tracking technology represents a significant step in uncovering the intricacies of their behavior.

“We are still far from fully observing the entire yearly cycle of long-range bat migration,” Hurme conceded. “The behavior continues to be a mystery, but at least we now possess a tool that has illuminated some aspects.”

By persistently delving into these mysteries, researchers aspire to enhance their comprehension of bat migration, laying the groundwork for effective conservation methods and contributing to a wider understanding of animal migration.

The study is available in the journal Science.

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