Authors: D. Stewart, E. Mendes, K. Lee, M. Blum, L. Tedeschi, S. Webb

Animal-borne tracking systems have provided unique insights into when, where, why, and how animals move

and interact with the environment. GPS neck collars have been the standard for animal tracking studies, especially for mid to large-size mammals. However, new technological developments have helped to miniaturize

tracking devices (e.g., GPS ear tags), including battery size and longevity (e.g., using solar panels). We initiated

this study to quantify the difference in horizontal error and data loss between solar-powered GPS mOOvement

version 1 ear tags and GPS Vectronic Aerospace collars during stationary testing and while deployed on beef

cows (Bos taurus). Mean horizontal error was 41 m (± 1.8 SE) and 2 m (± 0.1 SE) for GPS ear tags and collars

during stationary testing, respectively; during animal testing, the distance between paired ear tag and collar

locations was 59.2 m (± 3.3 SE). Fix acquisition was 99.3% ± 0.3 SE for ear tags and 99.8% ± 0.2 SE for collars

during stationary testing. During animal deployment, fix acquisition changed to 30.7% (± 9.1 SE) and 100% for

ear tags and collars, respectively. Lower acquisition rates, driven by loss of battery life, and greater horizontal

error of GPS ear tags, while on animals, may introduce bias into estimates of movement and space use; GPS

collars appear to be less sensitive to these forms of bias. However, mOOvement GPS ear tag systems are more

economical than commercially manufactured GPS collars. Therefore, budgetary constraints, data resolution, and

study objectives will dictate which technology to use

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Stephen Webb

Research Assistant Professor

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