An Assessment of Cave Bats and Cave Resource Use on Siquijor Island, Philippines

Mentor: Jodi Sedlock
Students: Thomas Coben, Paul Senner

Project Abstract

During our five-week stay in the Philippines, we surveyed bats in Bandilaan National Park, the largest remaining patch of forest on the island, as well as two smaller forest patches. We also assessed the disturbance level and bat populations in twenty large caves throughout the island, and we conducted video-taped interviews with a diversity of stakeholders invested in cave conservation. We used harp traps and mist nets and captured 180 individual bats representing nineteen species. Despite our modest sampling effort, we documented several species of bats not previously known to occur on Siquijor Island. We also conducted several acoustic monitoring transects with the bat detector. Most of our time was spent locating and surveying caves. Our goal was to survey as many large, accessible caves as possible in order to assess the population and conservation status of cave-dwelling bats on the island. Surprisingly, we managed to assess twenty caves in four municipalities. Low species richness, small cave bat populations, and the conspicuous absence of fruit bat colonies and other, less common, cave-associated insect bat species distinguish Siquijor from other less disturbed karst areas in the Philippines. The apparent decline of cave-dwelling bats in Siquijor and other areas may mean not only a decline in biodiversity, but in the ecosystem services they provide as pollinators, seed dispersers and consumers of crop pests. We conducted many video-taped interviews with people invested in the conservation of caves and cave bats. We learned that – unlike in other areas of the Philippines – very few farmers use bat guano as fertilizer. This may be the result of extirpated cave bat populations and the virtual absence of guano to collect. Where there are still bats present, men occasionally collected bats to eat as palutan (beer food); bats, however, are not a staple food in any of the communities we visited. We also interviewed government officials, including the Provincial Environment and Natural Resources Officer in Siquijor and the Director of the Protected Areas and Wildlife Bureau in Manila. These interviews underscored how little government officers based in urban areas know about what is happening in rural areas.

Thomas Coben

As part of this research project, I learned much about bats and the threats they face on the island of Siquijor as well as in the rest of the Philippines. I witnessed firsthand the impact of guano mining and of cave ecotourism on bat populations and learned a great deal about Philippine culture through my interactions with local people. I also developed and refined my skills as a wildlife videographer. I am currently enrolled in an Independent Study with two faculty in the art department in order to turn my numerous video clips into a documentary on cave bat conservation in the Philippines which will be my primary contribution to this joint research project.

Paul Senner

This was my first trip to Asia and to the Philippines, and I found it richly rewarding. The country is a beautiful and diverse one, and rich in biodiversity. I discovered a way of life far removed from the supermarket culture of the United States, and also learned the importance of remaining close to the land. All this will help me become a better field biologist and citizen of the world. My work in this joint project has been to collect and analyze acoustic cave data as I prepare to present a poster display at the fall student research symposium at Lawrence University. I will also work directly with Professor Sedlock on a paper we plan to submit for publication. Our findings will become part of a presentation Dr. Sedlock will give in late October at the North American Symposium on Bat Research in Denver, Colorado.