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Explore how a team of researchers from the University of Ruhana used wildlife audio recording to…
Sri Lanka is the world’s fourth largest tea producer, and bats are the principal predator of insects on tea plantations. Bats are also considered good indicators of biodiversity and environmental changes. With so few studies on bats in tea plantations, there is a critical need to assess the diversity of bats to benefit tea plantations with insect pest regulation.
Tharaka Kusuminda from the University of Ruhuna and his team, initially used capture methods to assess the species composition and their abundance inside tea plantations. However, capture methods, such as nets and traps, were inappropriate for the open nature of the habitat. That’s where unattended wildlife audio recorders came in.
Fourteen sampling sites were selected. Two SM4BAT recorders with two SMM-U2 Ultrasonic Microphones and an Echo Meter Touch 2 Pro were tested in a fragmented forest patch at the University of Ruhuna to test different recording schedules and settings. Then field work began in mid-February 2019 in seven sites. The two Song Meter SM4BAT FS detectors fitted with SMM-U2 ultrasonic microphones were mounted on shade trees inside tea plantations, positioning one bat detector at the edge and the other at the middle of the tea plantation. Bat sounds were recorded in three consecutive nights in each site from sunset to sunrise to cover full nocturnal activity.
Initial analysis at the University with Kaleidoscope Pro software suggested the presence of 8 species of bats across different tea growing regions. The large number of feeding buzzes recorded confirmed that bats were using the tea for foraging. While this project is still in its early stages, Tharaka Kusuminda and the team hope to learn more about the secret lives of bats on the tea plantations of Sri Lanka.
Spectrogram of Eastern bent wing bat echolocation call.
Final results of this project will be shared with the Sri Lankan Forest Department, Department of Wildlife Conservation, and the tea industry to quantify how insectivorous bat activity and species richness positively affect the ecologically friendly tea plantation landscapes. This data will help drive policy development and land use planning to make tea plantations more bat-friendly to maximize their ecosystem services.