Gruesome recording reveals bats catching, killing and eating blackbirds in mid-flight | Animal behavior
Bats are generally considered harmless, albeit frightening, nocturnal creatures. But scientists have revealed a wilder side, after observing a greater noctule bat – Europe’s largest bat species – chasing, killing and devouring a robin in mid-flight.
The grisly recording reveals the bat as a fearsome predator, climbing up to 1.2 km (4,000 feet) before launching into a dive at breakneck speed in pursuit of its prey. Upon capture, the bat emitted a lethal bite and subsequent chewing sounds, recorded between echolocation calls, indicated that the bat had consumed the bird continuously during flight for 23 minutes without losing altitude.
“It is fascinating that bats are not only able to catch them, but also kill and eat them while flying,” said Dr Laura Stidsholt, co-author of the research based at Aarhus University. “A bird like that weighs about half the weight of the bat itself. It would be like catching and eating a 35-kilogram animal while jogging.”
Billions of birds migrate seasonally at night and long distances at high altitudes and their flight paths are known to intersect bat hunting grounds. Dr Carlos Ibáñez, from the Doñana Biological Station, in Seville, was the first to demonstrate that birds were an important food resource during the periods of pre-hibernation – autumn – and gestation – spring – after observing feathers in bat droppings 25 years ago. Other scientists were skeptical, however, and in the years that followed, Ibáñez and his colleagues deployed surveillance cameras, military radar, and ultrasonic recorders attached to hot air balloons in an effort to gather compelling evidence.
In the latest study, large noctule bats were collected from nest boxes in southern Spain and fitted with tiny “backpacks” containing instruments to record acceleration, altitude and audio, including echolocation calls. The data revealed two cases of bat attacks on migratory birds, one of which was successful.
This bat has been observed climbing to an altitude of 1.2 km, before encountering its prey. “The bat flies in stealth mode,” Stidsholt explained. “It’s dark, the bird doesn’t see it coming, it doesn’t hear the echolocation sounds. The bat has an advantage.”
Approaching closely – perhaps alerted by the bat’s wingbeats or its shadow – the bird suddenly entered a downward spiral. The bat was observed following a cat-and-mouse chase for more than a kilometer, during which the microphone recorded 21 distress calls from the robin. As the pair approached the ground, a final cry was heard from the blackbird, followed by 23 minutes of chewing sounds from the bat as it continued to fly at low altitude.
“From a human standpoint, I didn’t feel good,” Stidsholt said. “But on the other hand, the bat is a very rare species and it doesn’t do very well in southern Europe because of droughts and forest fires. So we want this species to feed well.”
Previously, Ibáñez had collected and stored in a freezer severed songbird wings found beneath bat hunting grounds. X-ray imaging and DNA analysis of 11 wings suggest that the bats bite and fling the wings – probably to reduce their weight and drag. Researchers believe the bats then stretch the membrane between their hind legs forward like a pouch, allowing them to eat the rest of the bird in mid-flight.
Elena Tena, from the Doñana Biological Station and lead author of the study, said: “Even though it evokes empathy for the prey, it is part of nature. »
The results are published in the journal Science.
