By Will McCarry
October 30, 2023
In an undisturbed cave, expedition finds ‘microbats’ once thought lost
6 min
Pacific sheath-tailed bats are vanishing across Oceania.
By any count, the species, scientifically known as Emballonura semicaudata semicaudata, was hurtling toward extinction.
But recently, that all changed. On one of Fiji’s least visited islands, an expedition led by Conservation International made a remarkable discovery: A cave containing thousands of Pacific sheath-tailed bats.
“We descended into a cave on the island of Vanua Balavu not knowing exactly what we might find,” Helgen said.
The entrance was small and concealed by vegetation, requiring the researchers to crawl in, descend down a waterfall, swim through a pool and navigate a series of ever-shrinking chambers. But once inside, tell-tale signs made it clear they were on the right track. The path was caked with bat droppings, known as guano, and the air was periodically lit with the rustle of beating wings above them. Finally, at the end of a lengthy tunnel, they emerged into a massive underground cavern.
“The air was thick with bats as we entered this cathedral-like chamber,” Helgen said. “Every direction I turned I could see them moving through my torchlight.”
Helgen conservatively estimates that the population in the cave hovers at approximately 2,000 to 3,000 bats — making it the largest bat roost for any species across the entire South Pacific.
“We also found the bats in a number of other caves,” Helgen said. “This is a really hopeful sign that the Lau islands are still a stronghold for the species. We have the local communities to thank for that.”
“We don’t see anything like that happening in this cave,” he said. “The local communities have quite clearly made a deliberate choice to not exploit nor disrupt the cave, ensuring the bats can thrive undisturbed.”
Mere Lakeba, who leads Conservation International's work in Fiji, underscored that these types of discoveries are essential to furthering conservation efforts for endangered species.
“There’s a tremendous opportunity to work with the local communities to learn about their relationship with the bats,” Lakeba said. “They have a profound understanding of the land, shaped by generations of traditional practices and wisdom. We have a lot to learn from them about this roost and they will be instrumental in leading efforts to help protect the space.”
“Bats not only play a vital role in their habitat by controlling insect populations. They also offer a huge benefit to agriculture and human health,” Helgen said. “If we can bring the Pacific sheath-tailed bats back to more places, it will be good for both nature and people.”
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