Guided by nearby villagers, the bat biologists descended into the mouth of a cave on Fiji’s distant island of Vanua Balavu. They slipped down a rock encounter, swam via an underground pool, clambered more than piles of guano and emerged into a cathedral-sized cavern “absolutely chockablock-full” of Pacific sheath-tailed bats, claims Kris Helgen, a mammal professional and chief scientist at the Australian Museum Exploration Institute in Sydney.

Hundreds of the animals crammed the cave like a cloud, and Helgen could come to feel the whoosh of their sensitive wings as they zoomed all over him in the darkish. “It was a amazing moment,” he states.

The April expedition, led by the nonprofit corporation Conservation Global, had not only identified the most significant acknowledged bat cave in the Pacific Islands, with a inhabitants conservatively believed at 2,000 to 3,000 the scientists had also found new hope for a creature they’d feared was racing toward extinction.

Pacific sheath-tailed bats have comfortable, chocolate-brown fur and attain just five grams—the weight of a nickel or a sheet of paper. A couple of million yrs in advance of human beings sailed across the Pacific and manufactured their homes on island immediately after island, these little bats undertook the very same astonishing journeys—by air. (A associated species, the a little greater Brazilian cost-free-tailed bat, can fly 160 kilometers in a solitary night.)

The Pacific Islands have 191 recognised bat species, from little insectivorous microbats this kind of as the four-centimeter-very long sheath-tailed bats to fruit-feeding on flying foxes that dangle in trees and have a wingspan of a meter. Persons in the area accumulate bats’ guano for fertilizer, hunt them for foodstuff and—in the Solomon Islands—even use their enamel as standard forex.

Sheath-tailed bats have been as soon as among the Pacific’s most widespread mammals but are now a person of its most threatened. Less than a century in the past they had been identified across Oceania, from Guam to American Samoa. Currently the four recognized subspecies are now considered to endure on just a handful of Micronesian and Fijian islands.

The archipelagic nation of Fiji is the “last stronghold” of the sheath-tailed subspecies Emballonura semicaudata semicaudata, says expedition member Siteri Tikoca, a Fijian conservation biologist and a Ph.D. candidate at the University of Adelaide in Australia. But in Fiji, as well, the bat’s populations have been plummeting.

Some critical roosts are now absolutely devoid of bats. Tikoca says she counted all around 1,000 sheath-tailed bats in 2018 in a cave on the island of Taveuni, approximately 120 km northwest of Vanua Balavu. By 2019, the forests had been cleared practically to the mouth of that cave—and just a several hundred bats remained.

Tikoca suggests finding these kinds of a balanced roost in the Vanua Balavu cave was a “beautiful” minute that rekindled her hope for these bats. But the Taveuni problem “emphasizes the have to have to safeguard them now simply because so considerably can materialize in a span of one year,” she suggests. “If we you should not do anything for it in Fiji, then we will drop this subspecies totally.”

Conservation International says it will now function with the area’s Indigenous communities to superior safeguard the cave. “We’re all the richer for the truth that they have appeared right after these landscapes, all those caves and ultimately these bats,” Helgen suggests.

The insectivorous bats are believed to play a vital part in the encompassing ecosystems, eating crop pests and managing sickness-bearing mosquitoes. Mastering additional about these creatures’ ecology is vital, Tikoca claims, and is a very important to start with stage towards possibly relocating sheath-tailed bats to some of their former haunts.

“This is these types of an amazing discover and a substantial gain for the species,” says Jon Flanders of Bat Conservation International, who was not concerned in the expedition. All over the world, 270 new bat species have been described since 2005, he says—and this most recent discovery implies other Pacific islands may perhaps shelter nonetheless much more winged surprises. “It just goes to exhibit how small we continue to know about bats,” he suggests.