The Bats That Hunt Songbirds in Mid-Air: Scientists Finally Solved a Major Mystery

https://youtube.com/shorts/INm5R0rwI7g?si=iACc2kR1TDKJhJmQ

Read the research:

Original 2025 research article:“Greater noctule bats prey on and consume passerines in flight” — Science

The original evidence from 2001:“Bat predation on nocturnally migrating birds” — PNAS/PubMed

Research data and code:Mendeley Data — Stidsholt et al. dataset

More about the discovery:Aarhus University — How Europe’s largest bat catches and eats birds mid-air

If you watched my recent Nature Is Lit episode about the 400-year-old painting that appears to show a noctule bat carrying a bird, you already know the ending to this story. Greater noctule bats really do hunt birds. But the research revealing exactly how they do it might be even more interesting than the painting.

For decades, scientists had evidence that something unusual was happening with the greater noctule bat, Nyctalus lasiopterus. This is Europe’s largest bat, and while insects are part of its diet, researchers began finding something much stranger in its poop: bird remains. In research published in 2001, scientists examined more than 14,000 fecal pellets from greater noctule bats in Spain and found feathers. Even more interesting was when those feathers appeared. Evidence of birds increased during spring and autumn bird migrations and virtually disappeared during June and July. The timing suggested the bats were taking advantage of the massive seasonal movement of small birds through the night sky.

That raised a huge question. Finding feathers in poop can tell scientists what an animal ate, but it cannot necessarily tell them how the animal caught its meal. Were these bats finding injured birds? Catching them near the ground? Attacking roosting birds? Or were they somehow chasing migrating birds through open air? Scientists suspected aerial hunting, but actually witnessing something happening hundreds of meters above the ground, at night, is a completely different challenge.

In 2025, researchers finally got their answer. A team working in southern Spain fitted 14 greater noctule bats with miniature biologging devices during spring bird migration. These tiny tags acted like flight recorders, collecting information about the bats’ sounds, movements, acceleration and altitude. Instead of scientists trying to watch the animals from the ground, the bats essentially carried the research equipment with them into the night sky.

The tags recorded 611 prey attacks. Most looked exactly like what scientists would expect from bats hunting insects: short pursuits involving relatively few echolocation buzzes and lasting only seconds. But two attacks were dramatically different. During these events, the bats climbed hundreds of meters into the sky and engaged in much longer, more intense pursuits. One of those hunts would finally give scientists the evidence they had been looking for.

During the successful attack, a greater noctule climbed to approximately 1,200 meters above its roost before detecting a migrating European robin, Erithacus rubecula. The bat then pursued the bird toward the ground for nearly three minutes. Throughout the chase, it repeatedly used echolocation to track its prey. That gives the bat an extraordinary advantage because many passerine birds cannot hear the ultrasonic frequencies used in greater noctule echolocation. The bat can essentially send out signals, receive information about where the bird is and adjust its pursuit while the bird cannot hear the very system being used to track it.

The robin was not simply flying in a straight line waiting to become dinner. Data from the pursuit indicated evasive vertical movements, suggesting that migrating birds may attempt escape maneuvers when attacked. Researchers think the birds might detect an approaching bat at close range through sounds such as wingbeats or possibly only once the predator is extremely close. What followed in the successful hunt was something scientists had never recorded this way before.

The bat caught the robin. Its biologging microphone recorded 21 distress calls from the bird. Then the researchers heard another sound: chewing. The tag recorded mastication sounds for approximately 23 minutes, and remarkably, the bat continued flying while it ate. It did not return to a perch to process its meal. It remained airborne.

That presents another biological challenge because a songbird is enormous compared with the prey most aerial insect-eating bats handle. Some passerines eaten by greater noctules can weigh more than half the body mass of the bat itself. Imagine capturing something a substantial fraction of your own weight while flying, controlling it, killing it and somehow eating it without falling out of the sky.

Researchers found clues about how greater noctules manage that problem by examining discarded bird wings recovered from their hunting areas. X-rays revealed distinctive bite damage, and DNA analysis connected some of the evidence directly to greater noctule bats. The findings suggest that after capturing a bird, the bat may bite off its wings. Removing them would help immobilize the bird while also reducing drag and making the remaining body easier to manipulate during flight. Researchers have proposed that this technique may have evolved from behaviors greater noctules already used to handle large flying insects. Evolution may not have needed to invent an entirely new hunting strategy. The bats may have simply scaled up the prey.

The discovery also reveals a predator-prey interaction occurring in a habitat we rarely think about as an ecosystem: the night sky. Huge numbers of small birds migrate after dark, sometimes traveling hundreds or thousands of meters above the ground. That creates an enormous seasonal food resource, but very few predators are capable of accessing it. Greater noctule bats have the flight ability, sensory system and hunting behavior necessary to exploit that resource.

There is still plenty scientists do not know. Importantly, only two of the 611 recorded attacks showed the distinctive characteristics of bird pursuits, with one providing the successful capture documented in detail. That does not mean these bats are constantly knocking songbirds out of the sky. Instead, the study gives researchers rare direct evidence of a behavior that is incredibly difficult to observe. Future research could help determine how frequently individual bats hunt birds, whether some bats specialize in bird hunting, how weather or migration intensity affects their success, and how important birds actually are to the bats’ seasonal energy needs.

And all of this brings us back to the 400-year-old painting we talked about in an earlier Nature Is Lit episode. Jan Brueghel the Elder’s 1611 painting Air appears to depict a noctule bat carrying a small bird in its mouth. Researchers recently pointed out the remarkable possibility that the painting captured this predator-prey relationship centuries before modern scientists could directly document it. We cannot know exactly what Brueghel saw or what information inspired the image, but the fact that a recognizable noctule appears with a bird makes the painting particularly intriguing.

For centuries, the evidence may have been sitting in an art museum. Then it appeared in bat poop. Finally, scientists strapped tiny microphones and motion sensors onto bats and followed them into the night sky.

Sometimes scientific discoveries happen because we find something completely new. Other times, we finally develop the technology to see something nature has been doing all along.

And THAT is why Nature Is Lit.