Collaborative project focuses on Livingstone’s fruit bat.

07.28.22

By Kristen Pope

Halfway between Madagascar and Mozambique lies a small chain of islands: the Comoros. Two of these remote islands are the only place on Earth known to be inhabited by the approximately 1,200 Livingstone’s fruit bats (also called flying foxes) known to exist.

Hanafi Dhihari, Dahari Comores

Dr. Isabella Mandl, Bat Conservation International (BCI) Endangered Species Interventions Research Fellow, and a team from NGO Dahari, including Nadia Ambdi Keldi and Badrane Ben Ali, are working together to learn everything they can about these Critically Endangered bats. The research is going to support Dahari’s landscape management strategy to protect bats and other species by counteracting the widespread deforestation on the islands, which is fuelled by poverty and unsustainable agriculture methods.  

This year, Dr. Mandl has spent over seven weeks on the islands so far, joining her Comoran colleagues in their fieldwork, and will return this fall. Conducting research in Comoros is challenging, and the locations where bats prefer—remnant pockets of forest—are often in rugged terrain, difficult to access for humans. A typical day in the field involves one to three hours of hiking up steep, slippery mountains in rain, fog, mud, and humidity followed by 8-12 hours of research.

Once the team reaches a site, they set up a massive net to catch the bats—which can have a wingspan of up to five feet—and hoist these nets high above the treeline. “To catch a bat this size, you need a really big net,” Mandl says.

Once the net is in place, the team waits. Catching a Livingstone’s fruit bat is especially challenging since they use heat currents to soar high in the air and survey their surroundings during the day—which means they often spot the nets and avoid them.

When they catch a bat, the team carefully affixes a GPS tracker to it. This year, the team has applied 10 GPS tags, and have collected data from seven so far. To download data, they need a direct line of sight to a tag and to be within a few hundred yards of it.

Dr. Isabella Mandl

The GPS data collected by the bats shows clearly which trees they visited at different times. It will help identify where the bats roost and where they feed throughout the upcoming months. It can even reveal where bats go to seek refuge during tropical storms. 

“It’s important to protect these island populations,” Mandl says. “They might be wiped out by a huge cyclone. With a tiny island and tiny populations, any big weather event can actually be quite critical.”

In August, the Comoran team will “ground truth” the data, validating the collected GPS points with on-the-ground observations, including finding individual trees and tree clusters the bats use to see if they’re fruiting or flowering, and if the bats are eating or roosting there. To make sure these important resources remain part of the Comoran landscape the NGO Dahari has worked directly with landowners since 2015 to protect individual trees that are crucial to bats and other species. Every tree matters when a Critically Endangered species relies on them, and this study should reveal just how important these sites are to the species.