In-Flight Snack 

During their yearly migration, many songbird species travel at night, partly to avoid daytime predators. 

Night skies, however, have their own hunters, and bats are among the most skilled and most lethal. 

After more than two decades of research, a new study has described how Europe’s largest bats hunt and capture small birds more than half a mile above the ground, eating them without even landing. 

“We know that songbirds perform wild evasive maneuvers such as loops and spirals to escape predators like hawks during the day – and they seem to use the same tactics against bats at night,” study author Laura Stidsholt said in a statement. “It’s fascinating that bats are not only able to catch them, but also to kill and eat them while flying.” 

Researchers attached high-resolution biologging tags to the backs of 14 greater noctule bats (Nyctalus lasiopterus), documenting two of them attempting to catch prey. These instruments track the bats’ movements, acceleration, altitude, and sounds, including echolocation calls, revealing their hunting techniques.  

One of the two bats successfully secured itself a snack. It was observed climbing to an altitude of almost 4,000 feet while it used its low-frequency, ultrasound echolocation calls to locate the bird. Unlike some insects, birds cannot hear the bats’ echolocation calls and might only notice danger when it’s too late. 

The bat then plunged vertically downwards, flapping its wings faster and harder to triple its speed while emitting a rapid series of short echolocation calls in a hunt that lasted almost three minutes and ended close to the ground. 

The bird, identified as a European robin (Erithacus rubecula), emitted 21 distress calls before going quiet. Then, the microphone recorded 23 minutes of chewing sounds from the bat as it flew at a low altitude. 

“While it evokes empathy for the prey, it is part of nature,” study author Elena Tena said in the statement.  

“We knew we had documented something extraordinary,” she added. “For the team, it confirmed what we had been seeking for so long.” 

Combined with X-ray and DNA analysis of songbird wings collected below the bats’ hunting grounds, the study indicates that bats kill their prey by biting them. Then, they bite off the wings, likely to shed weight and reduce drag, stretch it between their hind legs to form a pouch and begin snacking. 

“A bird like that weighs about half as much as the bat itself – it would be like me catching and eating a 35-kilo (77 pounds) animal while jogging,” said Stidsholt.