Use of Apple Airtag to track urban wildlife: Proof of concept with Harris's hawks

Abstract

Accurate tracking of the movement of wildlife is important for understanding the behavior, spatial use, and resource selection of a species. While traditional methods like Very High Frequency (VHF) transmitters have been widely used, newer technologies, such as GPS data loggers and Global System for Mobile Communications (GSM) transmitters, have provided more detailed data at a higher cost. We evaluated the effectiveness of Apple Airtags, a Bluetooth tracking device that can be purchased for ~US$30, for tracking Harris's hawks (Parabuteo unicinctus) in the Rio Grande Valley, Texas, USA. We tagged 9 Harris's hawks with VHF transmitters and 6 with Airtags, and we tracked their movements over 12 weeks. While VHF transmitters provided only 36 locations (approximately 4 locations per hawk) due to limitations of field time, Airtags yielded 236 locations (approximately 39 locations per hawk), of which 181 were usable for MCP analysis. The cost per location for usable data was significantly lower for Airtags, at US$0.96 per location compared to US$69.08 per location using VHF telemetry. We also conducted a home range analysis using the Minimum Convex Polygon (MCP) method. For the 3 Harris's hawks equipped with Airtags that provided sufficient data for analysis, we estimated a 95% MCP home range of 284 ha for an adult and 133.5 ha on average for 2 juveniles. Core 50% MCP home ranges were 31.9 ha for the adult and a mean of 13.5 ha for juveniles. Our results suggest that Apple Airtags can be used for tracking urban wildlife, allowing analysis of home range areas and spatial use patterns. We note, however, that there are limitations to this technology, including reliance on proximity to Apple devices and finite battery life, and studies should be designed with these limitations in mind. Airtags offer a low-cost alternative for researchers working with medium-sized and large species in areas with high human activity aiming to collect remote locations on wildlife.