Characterisation of a New Lightweight Lorawan Gps Biologger and Deployment on Griffon Vultures Gyps Fulvus

Abstract

Abstract 1. Information provided by tracking studies using satellite telemetry is providing ecologists with invaluable new insights into animal behaviour and movement strategies. Here we describe a new type of GPS (global positioning system) tracking device which makes use of a growing network of LoRaWAN (long range, low power wide area network) gateways. These tags have the potential to be a low weight and power consumption solution. 2. We characterise the GPS accuracy and data transmission range, including uplinks and downlinks, for the tracker using a series of standardised tests. Data transmission range was tested by visiting locations with line of sight to the LoRa gateway at distances up to 75km and recording whether data transmission was completed successfully from each location. These tests were complemented by a trial deployment of six devices on Griffon Vultures Gyps fulvus. 3. These LoRa tags reliably provided accurate GPS location estimates, particularly on shorter location acquisition cycles. At one-minute intervals the GPS location bias was 4.71m in the horizontal plane and 5m in the vertical plane while GPS precision, measured by standard deviation, was 3.9m in horizontal space and 7.7m in vertical space. GPS locations were less accurate on a longer acquisition cycle but still comparable with other commercially available tags. Ground based range tests revealed reliable transmission of multiple data payloads was recorded from a maximum distance of 40.7km. Initial results from a deployment on Griffon Vultures Gyps fulvus yielded useful information about flight speeds, height and transmission range during the first two weeks after tag deployment. 4. The LoRa tags demonstrated potential for effective use in the study of animal movement. The small size and power needs allows for flexibility in which combination of battery, solar panel, and housing they are paired with meaning that fully assembled tags can weigh less than 5g. The LoRaWAN gateway network does not yet allow global coverage, hence at present, this solution is best suited to the study of colonial species, where gateways can be installed on site, or species with consistent migration routes.