Some bats feast on songbirds midflight

Vampire bats are a staple of Halloween. But they’re not the one bats that deserve the title of creepy creature. Another species snatches birds out of the air for a grotesque midnight feast.

Songbird DNA has proven up earlier than within the poop of three bat species. So researchers knew these flying mammals ate extra than simply bugs. But how does a bat hunt a chicken? It seems that Europe’s largest bat, the higher noctule, can capture, rip apart and eat songbirds midflight.

Researchers shared these findings October 9 in Science.

Flying with bats

For years, scientists have questioned how higher noctules (Nyctalus lasiopterus) seize prey. But it’s exhausting to know what animals are doing excessive within the night time sky. The resolution: Track their actions, says Ilias Foskolos. He research the acoustics of dwelling issues at Aarhus University in Denmark.

Foskolos and his colleagues outfitted higher noctules with biologgers. These units had a number of sensors. Accelerometers recorded 3-D motion. Magnetometers logged course. Altimeters measured top within the sky, or altitude. And microphones captured sound.

These sensors tracked the bats’ nightly actions. Listening to the recordings “is like flying with the bats,” says Elena Tena. You can hear their wings flap and frog calls as they fly over marshes. Tena is a bat conservationist at Doñana Biological Station in Seville, Spain. That’s the place the crew captured and tagged bats for the research.

Microphones additionally captured the feeding buzzes bats made as they approached their prey. These buzzes, adopted by chewing sounds, indicated a profitable hunt.

Om-nom-nom

The researchers logged 611 searching occasions. Most concerned bugs close to the bottom. But two stood out. In each instances, the bats flew above the peak of migrating songbirds — greater than 1,200 meters (almost 4,000 toes) excessive. The bats then homed in on a chicken and approached with feeding buzzes.

The pitches, or frequencies, of these buzzes are too excessive for birds to listen to, Foskolos says. Both birds responded on the final second. They had been possible reacting to the bat’s contact or the sound of its wings. “They probably do dives and spirals” to flee, Foskolos says. “They seem to go vertically down.”

One chicken escaped close to the bottom. The different wasn’t so fortunate. Microphones captured its misery calls adopted by a 23-minute in-flight meal. Accelerometer knowledge confirmed the bat was flying usually whereas it chewed, Tena says. “Sometimes you could hear that it must be biting bone.”

Removing wings appears to be a part of the bats’ course of. “Sometimes, when we were capturing [bats], suddenly, some wings [would] fall to the ground,” Tena says. DNA from wounds on the wings confirmed the chunk of a higher noctule bat. And captured bats of the identical species have generally been caught with red-stained lips and feathers hanging from their mouths.

Though there isn’t any video of the bats searching birds, the research “provides compelling evidence that birds are caught in flight,” says Danilo Russo. This bat ecologist on the University of Naples Federico II in Italy was not concerned with the research.

 “We still know very little about this species,” Tena says. Yet this analysis is a leap ahead in understanding the higher noctule’s function as certainly one of Europe’s prime predators.

Data Dive:

1. What is altitude? What kind of sensor measures motion on this dimension?
2. What is the vary of altitudes proven on the graph? How does that evaluate to the peak of migrating songbirds?
3. How does the bat’s altitude change because it searches for prey? Why may this be?
4. How does the bat’s altitude change because it assaults its prey? Why may this be?
5. What is sound frequency? Roughly what frequencies are the songbird’s misery calls? About how lengthy does a misery name final?
6. What different sorts of measurements might provide extra perception into how bats eat birds midflight? How would you graph these knowledge?