An at-sea assessment of Argos location accuracy for three species of large whales, and the effect of deep-diving behavior on location error

• Published in: Animal Biotelemetry
• Main Authors: Ladd M. Irvine, Martha H. Winsor, Tomas M. Follett, Bruce R. Mate, Daniel M. Palacios
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2020
• Subjects: Argos error; Satellite telemetry; Satellite tracking; Cetaceans; Blue whale; Fin whale; Ecology; QH540-549.5; Animal biochemistry; QP501-801; Balaenoptera musculus; Physeter macrocephalus; Sperm whale
• Online Access: https://doi.org/10.1186/s40317-020-00207-x; https://doaj.org/article/7150a81d06484150b45fe6ff1507c3e1

Abstract Background Argos satellite telemetry is used globally to track terrestrial and aquatic megafauna, yet the accuracy of this system has been described empirically only for a limited number of species. We used Argos-linked archival tags with Fastloc GPS deployed on free-ranging sperm (Physeter macrocephalus), blue (Balaenoptera musculus), and fin (B. physalus) whales to derive empirical estimates of Argos location errors for these species, examine possible behavior-related differences, and test the effect of incorporating species-specific error parameters on performance of a commonly used movement model. Results Argos location errors for blue and fin whale tags were similar and were combined (n = 1712 locations) for comparison against sperm whale tags (n = 1206 locations). Location error magnitudes for tags attached to sperm whales were significantly larger than blue/fin whale tags for almost all Argos location classes (LC), ranging from 964 m versus 647 m for LC 3, respectively, to 10,569 m versus 5589 m for LC B, respectively. However, these differences were not seen while tags floated at the surface after release. Sperm whale tags were significantly colder than ambient temperature when surfacing from a dive, compared to blue/fin whale tags (16.9 °C versus 1.3 °C, respectively) leading to larger changes in tag temperature during post-dive intervals. The increased rate of tag temperature change while at the surface was correlated to increased error magnitude for sperm whales but not blue/fin whales. Movement model performance was not significantly improved by incorporating species-specific error parameters. Conclusions Location accuracy estimates for blue/fin whales were within the range estimated for other marine megafauna, but were higher for sperm whales. Thermal inertia from deep, long-duration dives likely caused transmission frequency drift and greater Argos location error in sperm whales, as tags warmed at the surface during post-dive intervals. Thus, tracks of deep-diving species may be less ...