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Hart et al. Movement Ecology (2021) 9:1
Drivers of realized satellite tracking
duration in marine turtles
Kristen M. Hart1*
, Jacquelyn C. Guzy1 and Brian J. Smith2
Background: Satellite tags have revolutionized our understanding of marine animal movements. However, tags
may stop transmitting for many reasons and little research has rigorously examined tag failure. Using a long-term,
large-scale, multi-species dataset, we evaluated factors influencing tracking duration of satellite tags to inform study
design for future tracking studies.
Methods: We leveraged data on battery status transmitted with location data, recapture events, and number of
transmission days to probabilistically quantify multiple potential causes of failure (i.e., battery failure, premature
detachment, and tag damage/fouling). We used a combination of logistic regressions and an ordinary linear model
including several predictor variables (i.e., tag type, battery life, species, sex, size, and foraging region).
Results: We examined subsets of data from 360 satellite tags encompassing 86,889 tracking days deployed on four
species of marine turtles throughout the Gulf of Mexico, Caribbean, and Bahamas from 2008 to 2019. Only 4.1% of
batteries died before failure due to other causes. We observed species-specific variation in how long tags remain
attached: hawksbills retained 50% of their tags for 1649 days (95% CI 995–1800), loggerheads for 584 days (95% CI
400–690), and green turtles for 294 days (95% CI 198–450). Estimated tracking duration varied by foraging region
(Caribbean: 385 days; Bahamas: 356; southern Gulf of Mexico [SGOM]: 276, northern Gulf of Mexico [NGOM]: 177).
Additionally, we documented species-specific variation in estimated tracking duration among foraging regions.
Based on sensor data, within the Gulf of Mexico, across species, we estimated that 50% of tags began to foul after
83 95% CI (70–120) days.
Conclusions: The main factor that