Abstract
Automated radio telemetry systems (ARTS) have the potential to revolutionise our understanding of animal movement by providing a near-continuous record of individual locations in the wild. However, localisation error in data generated by ARTS can be very high, especially in natural landscapes with complex vegetation structure and topography. This curtails the ecological questions that may be addressed with this technology. Here, we set up an ARTS grid in a valley with heterogeneous vegetation cover in the Colombian high Andes and applied an analytical pipeline to test the effectiveness of localisation methods. We performed calibration trials to simulate animal movement in high- or low-flight, or walking on the ground, and compared workflows with varying decisions related to signal cleaning, selection, smoothing, and interpretation, along with four multilateration approaches. We also quantified the influence of spatial features on the system’s accuracy. We tested the grid by deploying tags on two high-altitude hummingbirds, the Great Sapphirewing (Pterophanes cyanopterus) and Bronze-tailed Thornbill (Chalcostigma heteropogon). Results showed large variation in localisation error, ranging from only 0.4–43.4 m from known locations up to 474–1929 m, depending on the localisation method used. The lowest average median error across calibration tracks was 105m. In particular, we found that the selection of higher radio signal strengths and data smoothing based on the temporal autocorrelation in movement data are useful tools to improve accuracy. Moreover, the variables that significantly influence localisation error include terrain ruggedness, height of movement, vegetation type, and the location of animals inside or outside the grid area. In the case of our study system, thousands of location points were successfully estimated for two hummingbird species that previously lacked movement ecology data. Our case study on hummingbirds suggests ARTS grids can be used to estimate small animals’ home ranges, associations with vegetation types, and seasonality in occurrence. We present a comparative localisation pipeline, highlighting the variety of possible decisions while processing radio signal data. Overall, this study provides guidance to improve the resolution of location estimates, broadening the application of this tracking technology in the study of the spatial ecology of wild populations.
Original language | English |
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Article number | e70405 |
Number of pages | 15 |
Journal | Ecology and Evolution |
Volume | 14 |
Issue number | 10 |
Early online date | 10 Oct 2024 |
DOIs | |
Publication status | Published - Oct 2024 |
Bibliographical note
We are grateful to all students, park rangers, and volunteers that supported and participated in fieldwork. They braved through the extreme weather of the paramo and a muddy valley with challenging slopes and prickly vegetation, carrying heavy equipment and doing intense physical work. We are particularly thankful to Juan Pablo Ríos, Manuela Lozano, Jonathan Espitia, Sarah Chaves, Angie Rodríguez, Ana Melisa Fernandes, Miguel Ángel Muñoz-Amaya, Aaron Skinner, Daniel Mancera, Fredy García, Luisa Díaz, Ángela María Uribe, Alfonso Rueda, Adriana Rueda, Diego Rueda, Michael Spence and Santiago Cepeda. We also thank our drone pilots, Nicolás Skillings and Carolina Arévalo, Jessie Williamson for sharing experiences in hummingbird tracking and research, Luis Guillermo Linares for giving initial advice and support, Leonel Herrera-Alsina for help running code on the cluster, Stephen Palmer, Rebekka Allgayer and Tamsin Woodman for suggestions on the methods, David Sragli, Rufus Behr and Alice Scarpa for initial coding approaches, Chingaza National Natural Park staff and management, especially Juan Camilo Bonilla-C., for all the support in the field, and Premium 3D for designing a tag chassis specifically suited for hummingbirds. NERC, Rufford Foundation, University of Washington Department of Biology, and School of Biological Sciences University of Aberdeen funded this work and we are grateful for their support.Data Availability Statement
All data and code are available in the Dryad Digital Repository at https://doi.org/10.5061/dryad.3ffbg79t3 and Zenodo at https://doi.org/10.5281/zenodo.13768241.Keywords
- Andes
- Colombia
- hummingbirds
- movement ecology
- multilateration
- paramo
- state-space models
- Trochilidae