Bats in tea: Acoustic identification of bats in plantation agriculture landscape and their conservation monitoring
University of Ruhana, Department of Agricultural Biology
I received two SM4BAT recorders with two SMM-U2 Ultrasonic Microphones and an Echo Meter Touch 2 Pro in early October 2018. First, I tested each of the recorders overnight in fragmented forest patch at faculty of Agriculture, University of Ruhuna, Kamburupitiya, and further tested for different recording schedules. I have trained my research assistants, Mathisha Karunarathna and Chamara Amarasinghe, regarding every steps before install (includes opening recorder, insert batteries, insert memory cards, connect microphone cable, adjust different settings) and mounting recorders and microphones in the field. And also, we were learnt about how create recording schedules and what is the recording schedule of present study. Data analyzing part hasn’t been started yet. Test recordings were made using non rechargeable batteries and low capacity memory cards available with us. Rechargeable batteries, a battery charger and high capacity memory cards will be purchased in January 2019 from additional funds. Echo meter touch 2 pro was tested using Android operated smart phones by the team during same field testing sessions.
We are in a process to extend our permissions to conduct field works in all selected tea plantations from plantation managers and land owners and applied for extend our bat capture permit from Department of Wildlife Conservation, Sri Lanka. We hope to start out first field works on early February 2019 in 14 tea plantations representing all tea growing agro-ecological zones in Sri Lanka. Most of tea growing areas in the country have been affected by heavy rain falls and landslides during last few months. Weather in the country is presently becoming normal and hopefully we will gather very useful data regarding bat diversity and activity patterns soon.
We have started field work in mid February 2019 and field works conducted in seven sampling sites including Ginigathhena, Pundaluoya, Nuwara Eliya, Knuckles, Udapussellawa, Idulgashinna and Morawaka up to now. We have identified suitable recording sites using Echo meter touch 2 pro and two Songmeter SM4Bat FS detectors fitted with SMM-U2 ultrasonic microphones were mounted on shade trees inside tea plantations with positioning one bat detector at the edge of tea plantation and other one at the middle of tea plantation. Bat sounds were recorded in three consecutive nights in each site from sunset to sunrise to cover full nocturnal activity of bats. Assuming the night length to be 11 hours on an average, we collected roughly 231 hours of acoustic data. During the field works, our field assistants Chamara Amarasinghe, Mathisha Karunarathna and Sameera Suranjan were trained well about bat research. Now, they are well-trained not only in setting up bat detectors but also in identifying different genera of bats from recordings.
We have started analysing the recordings at University of Ruhuna using Kaleidoscope Pro software. Initial analysis suggests that we have recorded about 08 species of bats across different tea growing regions. Many feeding buzzes in the sound collection are indicating the promising use of tea plantations for bat foraging. Another interesting thing is different social calls of different bat species recorded during this sampling session. I hope that, we can learn a lot from these bat sound recordings about the secret lives of bats in tea plantations of Sri Lanka.