DHAKA — Scientists have published the first record of the great Himalayan leaf-nosed bat in Bangladesh, dropping another pin on this wide-ranging species’ distribution map across Asia and highlighting the importance of continued biodiversity surveys in Bangladesh.

The species, Hipposideros armiger, was found in a cave in the Chittagong Hill Tracts in southeastern Bangladesh during field surveys between July and December 2023, according to a newly published study.

“We were thrilled to confirm this species in Bangladesh,” said lead researcher M. Abdul Aziz, a professor in the Department of Zoology at Jahangirnagar University.

“It’s an exciting moment for both local and global bat conservation efforts, as this discovery not only adds to the national fauna but also provides a deeper understanding of the species’ distribution across South Asia.”

H. armiger, among the larger of the leaf-nosed bats, has a wide distribution stretching from India in the west to China in the east, and as far south as Malaysia. Until last year’s discovery, however, its presence in Bangladesh had never been confirmed by scientists.

How it was identified

The species is a high-altitude cave dweller known for its distinctive nose-leaf structure, a crucial part of its echolocation mechanism that helps it navigate in the dark. The cave in which Aziz and his team found it is a culturally important one in the region. It has long served as a spiritual retreat for a local Buddhist monk, and is now also recognized for hosting a colony of these bats that roost in its cool, dark depths, the researchers said.

To confirm the bats as the species H. armiger, the researchers caught specimens and measured key physical traits such as forearm length, head-body size, and ear length, Aziz said. They also took close-up photographs of its distinctive nose-leaf, a key identifier for the species.

“Hipposideros armiger stands out from similar bat species with its longer forearms, dark brown fur, and a fleshy outgrowth behind its nose-leaf — features that confirmed its identity,” Aziz said.

The H. armiger colony that they found in the cave is estimated to number around 75-80 individuals. The cave also hosts other bat species, including horseshoe bats from the genus Rhinolophus and some as-yet-unidentified insect-eating bats.

Why this discovery is important

Conservationists say the discovery of the species in Bangladesh is a major milestone for the understanding of the country’s bat species. A 2022 review listed 31 bat species with a confirmed presence in the country. It also noted that while there were no confirmed reports of H. armiger in the country, it’s presence here was “highly probable.”

Despite this wealth of bat diversity, little is known about many of the species. More than half are considered “data deficient” on the IUCN Red List, which means not enough is known about their population trends and threats to make a conservation assessment about them. H. armiger is listed as a species of least concern by the IUCN, given its wide distribution and large population across its range.

“With this discovery, we now have a clearer picture of the diversity of bat species in Bangladesh,” Aziz said. “But there’s still much to be done to fully understand the distribution and ecological role of bats in the country.”

The Chittagong Hill Tracts, in particular, where the great Himalayan leaf-nosed bat was found, are a known biodiversity hotspot, thanks to their lush forests and dramatic topography. Researchers have long made the case that the region remains underexplored, and have called for more surveys to uncover the many species still hidden in its caves and forests.

Conservation challenges ahead

The cave where H. armiger was discovered is protected by local authorities due to its spiritual importance, but increased human activity could pose risks to the bats. Researchers cite rising numbers of visitors or human encroachment into the area.

“While this cave is currently safe, there is always the potential for human disturbance,” Aziz said. “It’s critical to protect these habitats to ensure that species like H. armiger can continue to thrive in Bangladesh.”

Bats play a crucial ecological role, controlling insect populations and pollinating plants, making their protection vital to maintaining ecosystem balance. The research team is calling for further studies in the Chittagong Hill Tracts and beyond, aiming to build a more comprehensive inventory of the country’s bat species.

As scientists continue to study the caves of Bangladesh, this new discovery serves as a reminder of the importance of preserving the country’s natural habitats and the remarkable species that depend on them.

Banner image: The bats were found in a cave in the Chittagong Hill Tracts in southeastern Bangladesh during field surveys between July and December 2023. Image by M. Aziz.

Rumors and misconceptions threaten tokay geckos in Bangladesh

Citations:

Aziz, M. A., Marma, A. S., Hamza, A., Rahman, M. A., Rahman, M. A., & Naznin, S. (2024). First record of Great Himalayan leaf-nosed bat, Hipposideros armiger (Hipposideridae) from Bangladesh. Mammalia, 88(5), 451-454. doi:10.1515/mammalia-2024-0003

Ul Hasan, M. A., & Kingston, T. (2022). Bats of Bangladesh — A systematic review of the diversity and distribution with recommendations for future research. Diversity, 14(12), 1042. doi:10.3390/d14121042