The automatic LoRa-enabled radio tracker for wildlife monitoring in remote environments

Biologging has transformed wildlife research by providing detailed insights into animal movement and behaviour. Archival tags are often used on animals that exhibit site fidelity or predictable movement patterns, as these behaviours increase the likelihood of recovering the tag and accessing the stored data. To facilitate recovery, archival tags are frequently paired with Very High Frequency (VHF) transmitters that indicate the presence of a tagged animal within detection range. When animals return only briefly to predictable but difficult-to-access locations, timely detection of these signals is essential for successful recapture and tag retrieval. Automated VHF monitoring can reduce the need for repeated manual surveys, but existing systems often rely on proprietary hardware and software, provide limited remote data access, or require substantial power and infrastructure, limiting their applicability in remote, dynamic, or extreme environments. To address these limitations, we developed ALERT (Automatic LoRa-Enabled Radio Tracker), an automated radio-telemetry system that combines custom-built, highly sensitive VHF receiving stations with Long Range Wide Area Network (LoRaWAN) communication. ALERT continuously scans for uncoded VHF signals, detects them using a custom algorithm, and wirelessly transmits detection scores to a central gateway for near-real-time visualization of animal presence. The system can be assembled from commercial off-the-shelf components and does not require specialized electrical engineering expertise. ALERT was tested at Atka Bay, Antarctica, from November 2024 to January 2025, during which 18 adult emperor penguins ( Aptenodytes forsteri ) were equipped with archival data loggers and VHF transmitters. Three receiving stations were deployed around the colony to notify researchers when tagged penguins returned from foraging trips, enabling timely recovery of biologgers, as penguins may remain available for recapture for only a few hours before departing again. Each station reliably detected VHF signals within an effective range of approximately 0.8 km and successfully alerted researchers to the return of all tagged penguins within minutes. We describe the hardware and software architecture of ALERT and evaluate system performance under Antarctic conditions. Our results demonstrate that ALERT is an easily deployable and scalable solution for automated VHF telemetry in remote and logistically challenging environments where communication infrastructure is unavailable.