As It Happens

Biggest library of bat sounds catalogues world's rare species

An international team of researchers has been busy recording bat calls in some of Mexico's most remote areas, to create the biggest library of bat sounds ever.
The pallid bat (Antrozous pallidus) (Veronica Zamora-Gutierrez)

You'd be forgiven for thinking the Bat Library is a fictional wing in Batman's underground cave, where he stores all his leather-bound books on crime fighting. But it's very real, and infinitely cooler than a comic book fantasy.

The library is actually the biggest collection of bat sounds ever created. It's the result of efforts by an international team of researchers, who have recorded more than 4,500 bat calls in some of Mexico's most remote areas. The collection represents about half of the 130 bat species found in Mexico. 

The pallid bat, the California leaf-nosed bat, the ghost-faced bat, the pocketed free-tailed bat, Parnell's mustached bat, The Western yellow bat, Allen's big-eared bat, The Hoary bat
Professor Kate Jones (Kate Jones/Twitter)

Details of the research are published in the journal Methods in Ecology and Evolution. Kate Jones, a professor at University College London, and a member of the Zoological Society, is one of the authors. She tells As it Happens guest host Laura Lynch how the project got off the ground.
Bats in Mexico are really special, because it's one of the bat hotspots in the whole world.- Professor Katie Jones

"My PhD student was from Mexico, originally and she was really interested in understanding what Mexican bats were facing in the future," Jones explains. "She wanted to understand what the pressures were — of climate change, land-use change, and pollutants — on the bats of Mexico. Bats in Mexico are really special, because it's one of the bat hotspots in the whole world."

That's largely due to the variety of habitat that Mexico offers, says Jones — from hot deserts, to the lush green rainforests of the south.

The Reserve El Pinacate in northern Mexico, where some of the bat sounds were collected (Veronica Zamora-Gutierrez)

Jones says her student, Veronica Zamora-Gutierrez, traveled all around Mexico, placing little tiny mesh nets to catch the bats. She would then record them and determine their species before releasing them back into the wild.

Veronica Zamora-Gutierrez (Courtesy of Kate Jones)

Of course travelling remotely in Mexico presents unique challenges and is not without danger.

"She found the Northern areas are quite badly sampled for bats. And so she headed there to complete some of the libraries. Some of those areas are tough to be in. But she's a pretty tough cookie. She's as hard as nails."

Jones explains that the study relies on artificial-intelligence technology for accurate classification, because the human ear isn't well-equipped to distinguish between the various calls.

"We use some techniques like Siri on your phone, so some speech-recognition algorithms, to start analyzing what call it is. We're actually quite bad at telling bat calls apart. And there are lots and lots of bat calls that sound exactly the same."

As for what lies ahead, Jones anticipates that the research may embark on a trip into the past "...to understand how these calls have evolved through time, and understand what the ancestral bat might have sounded like. And maybe reconstruct that sound so everyone can hear it. That would be fun."