Chelonia BatBug
RDUK has been field testing The ‘BatBug’, a new product in development at Chelonia. Based on the F-POD marine passive acoustic monitoring device, the BatBug is a solar powered acoustic logger designed to capture Bat calls but also works for many small mammals, birds and insects vocalising in the ultrasonic range. Chelonia is working on a basic Bat species classifier, this is a significant task but we hope our raw data recordings at a sample rate of 1000KHz (1 million samples / second), upsampled to 4000KHz sample rate (4 million samples / second) in the the FPGA processor giving us a resolution of 250 nanoseconds, may reveal some subtle characteristics to help classify Bat calls into groups.
BatBugs run indefinitely on a 20 watt solar panel and 12v sealed lead acid cell. Several were deployed on uninhabited islands around South West England in 2021 – 2023. We worked with National Trust, Wildlife Trusts, and local Bird Ecologists to access these sites, the BatBugs were running for a year.
The software used to analyse the recordings is based on the F-POD software from Chelonia’s marnine acoustic logger. As well as amplitude, frequency and tonality, the logger records, light levels and temperature every minute. A ‘Report.txt’ file is created when the logger starts up and shuts down, so when the rodents were chewing the cables, the logger would reboot and keep running but I could see when these events were taking place. Very useful information.
Constant frequency bat calls from a BatBug identified as Lesser Horseshoe by the classifier
Frequency Modulated Call from a BatBug – Much harder to classify
Frequency Modulated Call from a BatBug – Much harder to classify
Some of the things the BatBugs coped with were Gull investigations pecking through the mesh covering the mic, rodents chewing the cables and small insects crawling in through the water pathways. All the BatBugs kept running in all conditions. BatBugs also work as self-contained devices running on 18AA Alkaline Batteries for quick easy deployment.
This BatBug ran through the summer of 2022 on top of Great Mew Stone off South Devon, we detected Lesser Horseshoe Bats. In the Autumn we moved the BatBug lower down to an Elder Grove. It has been there ever since, we are looking forward to recovering that data.
Constant frequency bat calls from a BatBug identified as Greater Horseshoe by the classifier
Frequency Modulated Call from a BatBug – Much harder to classify
Quasi Constant Frequency Call from a BatBug – Pipistrelle shape.
Zooming in on a Bat call with BatBug software
Parallel data at Calamansac SSSI with BatBug recording at 1000KHz sample rate and the SM4BAT recording at 500KHz sample rate.