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VOLUME 23, NO. 3 Fall 2005

A Frightful Stairway
Cave bats in Borneo
M.T. Abdullah et al

Ecotourism can be a powerful tool for bat conservation, especially in regions with little history of understanding or concern for bats. Whether it comes from 1.5 million Mexican free-tailed bats (Tadarida brasiliensis) swirling out from under a bridge in downtown Austin, Texas, or 20,000 large flying foxes (Pteropus vampyrus) rising from tree roosts in the Philippines, few things improve the image of bats more than the direct infusion of cash into a local economy.
Our upcoming book, Bats of Borneo (by M. T. Abdullah and Les Hall), describes major bat caves that attract – or could attract – ecotourists to Borneo. Our research for the book took us to Gomantong Cave in the state of Sabah in Malaysian Borneo, home to 600,000 to 2 million wrinkle-lipped bats (Chaerephon plicata), whose evening emergence is an awesome spectacle.
We hoped to study the bats from inside the cave and collect information that could offer help in effectively managing and protecting this important colony.
Our caving expedition, however, turned into a greater adventure than we had anticipated. Uncounted centuries of roosting bats provided a functional, if somewhat unsavory, staircase leading to the home of the bats.
Les first saw the fly-out of wrinkle-lipped bats during a BCI Founder’s Circle Trip in 1998. The cave is popular with both foreign and local tourists who come to see the bats and the spine-tingling harvest of swiftlet nests – the primary, and highly valued, ingredient for the bird’s nest soup that’s popular among the Chinese community.
Locals gave us directions to the part of the cave used by bats. They also noted that the area smells rather badly and no one ever goes there. We soon discovered just what they meant.
Gomantong Cave is a large, intricate cave system. The bats roost at the rear of a segment known as Simud Hitam (Black) Cave. Part of this segment is occupied by black-nest swiftlets (Collocalia maxima), which make their nests mostly out of the birds’ saliva.
We emerged from the rain forest at the base of a limestone cliff where the dark entrance to the cave was fronted by a small cluster of timber long-houses used by those who collect the nests. Inside the cave, ladders of twined rotan vine and hardwood rungs hung from the ceiling at dizzying heights. The nest collectors dangled from these ladders like flies in a spider web. Another type of ladder, made from a hardened bamboo pole, pivoted around the cave to reach the highest nests.
Inside the cave, we found ourselves at the base of a steep rock pile left by a collapse in the cave roof. Above the rocks, daylight streamed through a large hole some 200 feet (60 meters) above the floor – the exit through which the wrinkle-lipped bats emerge at sundown. After scrambling up and around the rock pile, we had expected to encounter a tall chamber, since wrinkle-lipped bats almost always roost in cracks and on ceilings very high up in large caves. Most roost sites are inaccessible to humans.
What we found instead was both stunning and disconcerting: An enormous, chocolate-brown cone of guano rose more than 100 feet (30 meters) high. Here was a stairway to the wrinkle-lipped bats. The top of the guano mountain was lost in the darkness of the chamber, but we could hear the chattering of bats that seemed to be daring us to climb the pile.
With some trepidation, we stepped off the rocky floor – and immediately sank knee-deep in guano. Then we began trudging upwards as our boots filled with guano. Halfway up, the guano grew softer and our legs sank even deeper. The smell of ammonia was overpowering. Three-quarters of the way up, we were thigh-deep in guano and leaning forward almost on all fours. Our eyes began weeping and our throats burned from the ammonia.
Finally, we made it to the top and stood there on wobbly, aching legs. Still more than 15 feet (5 meters) below the ceiling, we aimed our flashlights into several deep crevices, causing the bats to add substantially to the guano pile. We could see very little in the dark crevices, although the bats’ chattering increased markedly as they noted our intrusion.
Then we ventured into a side passage with a ceiling height of about six feet (two meters) – and suddenly we saw bats everywhere. Most were wrinkle-lipped bats ranging from naked newborns to gray-furred older pups and on up to adults. The young and their mothers occupied the deepest pockets in the ceiling, squeezed in tightly with just their heads poking out. Adult males often hung below the females and young on prominent projections from the ceiling. We also saw small clusters of Philippine horseshoe bats (Rhinolophus philippinensis) and fawn roundleaf bats (Hipposideros cervinus). Many females of both species were obviously pregnant.
At this height, the cave was extremely hot and humid, just what horseshoe and leaf-nosed bats look for in maternity sites. Perhaps this low-ceiling area also offered a choice microclimate for rearing young wrinkle-lipped bats? That’s a question for another day. With sweat rolling off our foreheads and our glasses and cameras fogged, it was time to get out – both because of the extreme conditions and to avoid unnecessarily disturbing the bats.
Descending the pile was easy: We’d take one step and slide another until we reached the bottom. The total time of our journey up and back down the guano mountain probably lasted just 20 minutes, but the experience is guaranteed to remain in our memory forever.
Bat colonies play a vital role in maintaining healthy environments and economies, and many communities are also recognizing their cash value as destinations for tourists. Around the Pacific, bats are becoming valuable tourist attractions, with popular colonies in the Philippines, Thailand, Malaysia, Indonesia and elsewhere.
This conspicuous cash value is generating new interest in protecting bat colonies. Now we need to gather and pool our knowledge to develop effective, long-term management strategies to ensure that the bat colonies remain healthy and continue to provide the spectacular emergences that so enthrall visitors from around the world. The great caves of Borneo require special, continued attention and monitoring to ensure that the bats can also continue to co-exist with the harvesting of bird’s nests.
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M.T. ABDULLAH is an Associate Professor at the Universiti Malaysia Sarawak and Head of the Animal Resource Science and Management Program. He studies biodiversity and molecular ecology of bats in Borneo and Malaysia. IMELDA VIVIAN PAUL is a postgraduate student studying bats at the Universiti Malaysia Sarawak. LES HALL, a member of BCI’s Scientific Advisory Board, recently retired from the University of Queensland but is still involved in bat research and is a Visiting Fellow at Universiti Malaysia Sarawak.

All articles in this issue:
A Frightful Stairway
Besieged Bats of Mentawai
From Superstition to Understanding
Battered by Harsh Winds

Unless otherwise noted, all images are copyright ©Merlin D. Tuttle and/or ©Bat Conservation International