ALERT: The Automatic LoRa-Enabled Radio Tracker for Wildlife Monitoring in Remote Environments

Biologging has advanced wildlife research by providing detailed insights into animal movement and behaviour. However, data recovery in remote areas without cell coverage remains a major challenge, often relying on costly satellite communication or labor-intensive manual recovery of archival tags, typically through Very High Frequency (VHF) tracking. Current automated VHF monitoring approaches often rely on proprietary hardware and software, offer limited wireless data retrieval options, and require substantial power or infrastructure, which prevent their applicability in remote or extreme environments where they are most needed. Hence, manual tracking is still the most commonly used method. To address these limitations, we developed ALERT (Automatic LoRa-Enabled Radio Tracker), a simple radio-telemetry system that integrates custom-built receiving stations with Long Range Wide Area Network (LoRaWAN) communication. ALERT continuously scans for non-coded VHF signals, detects them using an adaptable custom algorithm, and wirelessly transmits presence information to a central gateway for real-time visualization. ALERT can be built with commercial off the shelf parts and does not require specialized electrical engineering knowledge. The system was tested at Atka Bay, Antarctica, from November 2024 to January 2025. During this period, 18 adult emperor penguins ( Aptenodytes forsteri) were equipped with archival data loggers and VHF transmitters. To facilitate recovery of these archival tags, ALERT was deployed to automatically notify the field team when VHF-tagged penguins returned to the colony from foraging trips. Three receiving stations were strategically installed in the vicinity of the colony, at distances of up to 5 km from the LoRa gateway. Each station reliably detected VHF signals within an effective range of approximately 0.8 km and successfully alerted researchers in real time to the return of all VHF-tagged emperor penguins. This study describes the hardware and software architecture of ALERT and analyses system performance as a function of transmitter-receiver distance, weather conditions, and antenna configuration. It also evaluates the reliability of LoRaWAN data transmission under Antarctic conditions, including factors influencing packet loss and transmission delays. Our findings demonstrate that ALERT is a low-cost, low-power, and scalable solution for automated VHF telemetry, capable of supporting wildlife monitoring in remote and logistically challenging environments.