Europe’s Largest Bat Can Catch and Devour Birds in Mid-Flight

The European night sky is far from an empty space. Every night, migratory birds cross it at high altitude, guided by the stars and magnetic fields. But some of these travelers will cross paths with an unexpected hunter. Still unknown to the general public, the great noctule reinvents the rules of aerial predation. This discreet but formidable flying mammal reveals behavior that scientists thought was improbable.

bats of Europe by its impressive size. Its wingspan sometimes reaches 45 centimeters, which makes any confusion difficult. For a long time, biologists have noticed strange clues when studying its excrement. In particular, there were feathers, sometimes whole, mixed with the remains of insects. These observations suggested that it also captured birds. However, without direct proof, this idea remained questionable.

For almost twenty-five years, the Spanish biologist Carlos Ibáñez, from the Doñana Biological Station in Seville, has been trying to unravel this mystery. The idea that a bat could capture birds in flight seemed daring. Many researchers considered it unlikely, because many passerine species are almost half the weight of a large noctule. Despite these doubts, Ibáñez's team persevered, installing automated artificial shelters and tracking the animals' movements using microchips.

The large noctule is today among the most threatened in Europe, according to the IUCN Red List. The progressive deforestation of mature forests, where it nests and reproduces, further accentuates its vulnerability. However, it is in the peaks and night skies that it has revealed one of the most astonishing behaviors ever observed in a flying mammal.

How the great noctule captures its prey in the sky

The secret of the great noctule has finally been unlocked thanks to technology. Researchers at the University of Aarhus in Denmark have developed mini-sensors weighing a few grams attached to the backs of two wild specimens. These technological objects continuously record the accelerations, altitudes and sound emissions of bats. By following their trajectories, scientists have reconstructed scenes worthy of a nocturnal wildlife film.

At more than a kilometer altitude, noctules spot migrating passerines invisible to the naked eye. Their ultrasonic calls, powerful but inaudible to birds, serve as their radar. Once the target is detected, the hunter dives suddenly, wings flapping, tripling its speed in a few seconds. According to the recordings analyzed, some chases lasted almost three minutes, in an aerial ballet of rare intensity.

In one documented scene, the prey, probably a robin, emits twenty-one cries of distress before silence falls. The sounds recorded afterwards are reminiscent of chewing noises. For more than twenty minutes, the great noctule continues to fly, chewing on its capture without ever landing. Researchers believe it folds the membrane between its hind legs to form a sort of pouch allowing it to eat in mid-flight.

According to the study published in Science, these bats first kill their victims with a bite, then tear off the wings to reduce aerodynamic drag. This behavior had never been observed in such detail in a flying predator. For Laura Stidsholt, co-lead author of the research, “ such a feat would be equivalent to a human catching and eating a 35 kilo animal while running “.

Why this discovery changes our understanding of bats

These results relayed by Popular Science profoundly call into question the usual image of European bats. Unlike the majority of insectivorous species, large noctules are interested in an often neglected resource. They target migratory birds that cross the sky at night. This bold dietary choice allows them to attack faster and larger prey. Thus, they push the known limits of aerial predation among mammals.

This behavior also demonstrates a remarkable sensory evolution. Noctules use lower echolocation frequencies, capable of detecting prey at long distances, while remaining imperceptible to birds. This strategy gives a decisive advantage in total darkness.

According to Phys.org, these findings should not worry bird advocates. The species is rare, and its impact on passerine populations remains negligible. On the other hand, understanding her lifestyle could help protect her. The data collected will be used to better guide the preservation of the forests where it takes refuge and to adapt conservation strategies to its unique behavior.

Thus, this silent predator reminds us that there remain, even in the heart of Europe, animals capable of inventing strategies that science has never seen before.