LB 36-296 - A Miniature Radio-Frequency Transmitter and 3D tracking Algorithm for Studying Bats and Birds

Radio-Frequency (RF) telemetry has been successfully used to track bats. However, use of RF telemetry in animal tracking has been limited by the relatively large transmitter sizes that could negatively affect the behavior of the animals to which they are attached, and the relatively short service life. The weight of the transmitter is a major constraint and as a result the smallest transmitters typically last less than two weeks. To study small animals and minimize the resulting bias introduced by the tag burden, biologists have been continually seeking smaller transmitters to obtain as-unbiased-as-possible data to support decision-makingWe advanced the state-of-the-art of radio-frequency (RF) transmitters by developing three options of a new RF transmitter that can address the research needs for the key bat species to understand wind turbine impacts: 1) Minimized the transmitter size and weight (0.16 gram; 8 km range) to study bats that could be too small to use commercially available RF transmitters; this option targets as the endangered species of Myotis. 2) Prioritized service life (0.40 gram; one year tag life at 15 second ping rate; 16 km range) over the transmitter size, weight and detection range; This option targets the tracking applications for studying the migratory behavior of hoary, eastern red and silver-haired bats, while still staying under the 5% tag-burden guideline. 3) Prioritized detection range (0.57 gram; 35 km range) while keeping the transmitter size and weight reasonable; This option is designed for studying the potential landscape scale attraction of bats to wind turbines and their fine-scale movements across one or more wind farms. We also develop a 3D localization algorithm for these transmitters that can provide high-resolution behavioral information of the tagged bats. The detection range of three RF transmitter designs and the accuracy and efficiency of the 3D tracking algorithm were validated in an operational wind farm. The new RF transmitters, which are small or possess longer service life, can collect bat movement information with the resolution needed for monitoring these animals at a landscape level scale as well as studying their behavior around wind turbines. Advancing the state-of-the-art of RF transmitters and tracking algorithms would greatly improve abilities to gather basic life history information, characterize bat habitat use, evaluate theories of bat attraction to wind turbines and improve species-specific risk modeling to develop appropriate mitigation strategies.