Bat researcher, Matt Struebig, began working at Camp Leakey in Tanjung Puting National Park three months ago to conduct a survey of bat species diversity in the park.
Surveying Bats at Camp Leakey
Matt started doing bat research in 2000 as a volunteer in Sulawesi, Indonesia and trained for a year before he began his own research. He has worked for the Malaysian Bat Conservation Research Unit, has trained students in Myanmar, and received his BSc and MSc in Ecology and Conservation. Matt is currently an Associate Researcher at University of East Anglia in Norwich, U.K. His PhD work focuses on the impact of forest fragmentation on genetic and community structure of tropical bats. He will be moving to Queen Mary University of London in September.
Matt wanted to conduct a bat survey in Camp Leakey because it is one of the few accessible places in Borneo where logging has not occurred. Bat diversity is a good indication of forest health, because many species have particular roost requirements for large, old trees. Matt created a team to assist him with his work including Dave White, Joanna Cartwright, and Rachel Payne from University of East Anglia and Miss Hetty and Miss Norma from University of Palangkaraya.
Weighing and sexing a bat
The team has worked out of three sites at Camp Leakey including Post Jalan 17 and Camp Wilkey. To capture bats, they have used harp traps and mist nets. Eight to ten traps are set each night across well-cleared trails and occasionally along streams to capture insectivorous bats. The traps are set 50 meters apart. The harp traps have a much higher capture success rate than mist nets when set in the forest, so the mist nets are rarely set and then mainly used to capture fruit bats.
Early each morning, the researchers remove the bats from the traps. Each bat is identified, sexed, has its forearm length and weight measured and their reproductive condition evaluated (pregnant, lactating, etc.) which helps the researchers determine the breeding season for each species. Some species breed seasonally while others breed year round. The research assistants collect standard measurements on 20 representatives of each species. These include tail length, tibia length, hind-foot length, and ear length. Then a hole-punch sized piece of the wing is taken so that recaptured individuals are known. This area quickly regrows as the membrane of a bat wing is one of the fastest growing tissues.
The researchers capture a minimum of 12 bats and up to 30 in an evening. The number collected each night varies depending on the rain patterns and proper trap set up (the strings must be tight and the trap well placed). If it rains during the night, the bats can see the strings of the trap and avoid it. Alternatively they may not fly during the rain. If it is dry for a long period, the catch rate also goes down, perhaps because insect aren’t as abundant. After almost three months, the team has collected data on over 680 bats.
Thus far 22 species of bats have been collected in the Camp Leakey area of the park out of over 90 species found in Borneo. The team has discovered three new species records for Indonesia, and several further new records for this region of Kalimantan. The species diversity in TPNP is less than other areas in Borneo since there are no caves in or near the park, but the species it does support are true forest specialists, and most of them would simply not be here if the forest was degraded.
The different species of insectivorous bats in the park feed on different types of insects. One of the first steps in understanding feeding patterns and partitioning of food resources is looking at the adaptations each species has for maneuvering around the forest and hunting for prey. Are there differences in the wing shape of each species which help in the partitioning? To find out, the research team photographs the wings of bats for further measurements and has set up a flight cage to measure the acuity of each species’ flight.
Inside a flight cage an obstacle course is created consisting of two sets of strings. The researchers release a bat into the cage and give each bat a score on how they maneuver around these strings. They record if a bat touches the string, if they fly between them, if they go around them, or if they avoid them. The results of this work will be tabulated over the next year.
The team will collect data through the end of July and the results will be compared to the few other sites that have been studied in south-east Asia. In its simplest form, the survey is finding out the species that Kalimantan’s coastal forests can support. However this forms the foundation for further studies that can evaluate the effect that the destruction of Borneo’s forests is having on its wildlife. The project is also making the first steps in determining how Bornean forest bats are adapted to their habitat, which can indicate the conservation needs of different species.
For more information about the project and the species caught, please contact Matt at email@example.com.