Even though the human ear can’t normally hear the ultrafast chirps, beeps, and whistles of bats, a new catalog of bat calls promises to make studying these flying mammals a whole lot easier. Previously, scientists had compiled the calls of European bats and even bats in New York City. But Mexico, a hot spot of bat diversity, was largely untouched. So a Mexican ecology graduate student spent 1.5 years traipsing through that country, combing through dense jungles and braving areas controlled by drug cartels to net more than 900 of the nocturnal creatures. Before releasing them, she recorded their calls, some of which you can hear—slowed down 10 times—in the video above. With additional data donated by other researchers, she compiled 4685 calls from 1400 individual bats. Using artificial intelligence software, her London-based team developed a computer program that distinguishes bat species based on the calls. Already, that group had developed a similar identification tool for 34 of Europe’s 40 bats. But this new caller ID is much more comprehensive, covering 59 of Mexico’s 130 bat species. Even if a bat’s call is not in the data set, the caller ID can make a “best guess” about the family of bat or what it’s likely to eat based on its similarity to known calls, the group reports today in Methods in Ecology and Evolution. In addition to growing the database, the team is now setting up a citizens’ science group to regularly visit key bat habitats in Mexico to listen in and find out how they are doing.

(Video credit: AAAS/Science)