Authors: D. Stewart, E. Mendes, T. Batter, J. Beaver, M. Blum, M. Cox, J. Dykes, M. Hoffman, K. Piecora, L. Tedeschi, E. Tomassetti, S. Wells, T. Werdel, S. Webb

Animal-borne global positioning system (GPS) technology is advancing rapidly, providing new opportunities to study animal ecology and improve livestock management. Evaluation of emerging GPS technologies is needed, particularly those incorporating autonomous solar charging and satellite, cellular, and Long-Range Wide-Area Network (LoRaWAN) data transmission. We quantified and compared the performance of GPS neck collars and solar-powered GPS ear tags using stationary trials conducted under varying canopy cover conditions. Using a crossover design, we evaluated fix acquisition probability (Pacq), horizontal error (HE), circular error probable (CEP), and, when applicable, battery longevity for 10 GPS devices (7 collars and 3 ear tags) produced by 9 manufacturers. GPS performance was generally consistent across manufacturers and device types and showed limited sensitivity to canopy cover. Devices using LoRaWAN maintained high Pacq (0.92–0.99) across canopy conditions, though HE (2.94–19.70 m) and 95% CEP (7.07–77.83 m) varied substantially among devices. Track Tag and 701x ear tags exhibited high Pacq, low HE and CEP, and sustained functionality throughout the study, indicating potential for wildlife and livestock monitoring. A minimum of 84 locations was sufficient for centroid variation to reliably represent HE. Horizontal error was centered on a device-specific centroid rather than the true location, resulting in systematic bias ranging from 0.96 to 3.50 m, except for one device (11.52 m). Overall, GPS ear tags achieved performance metrics comparable to traditional collars. These results can inform technology selection, though extrapolation beyond stationary conditions should be made cautiously, as GPS performance is often optimized under static deployments.

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Stephen Webb

Research Assistant Professor

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