No Rest for the Weary: Restricted Resting Behavior of Green Turtles (Chelonia mydas) at a Deep-Neritic Foraging Area Influences Expression of Life History Traits

For breath-holding marine animals, tradeoffs between ‘active’ and resting behaviors during periods of submergence can have consequences for acquisition and allocation of energy to vital life history requirements. In this study, we fitted 18 green turtles (Chelonia mydas) with detachable time-depth recorder (TDR) systems to obtain and analyze fine-scale dive behaviour and daily activity – with a focus on resting dive bouts – at Bahía de los Angeles (BLA), a warm-temperate foraging area in the Gulf of California, México. Our results showed that resting bout durations increased with water depths among all turtles, but patterns of resting bout durations and depths varied widely among individuals. To evaluate potential consequences to green turtles of tradeoffs between time spent ‘active’ versus resting, we also compared behavioral parameters (e.g. time spent resting, home range sizes) and life history traits (e.g. growth rates, body size at maturity) of green turtle populations from around the world, including BLA. We found that BLA green turtles spend less time resting, spend more time actively swimming and diving, occupy larger home ranges, and exhibit slower growth rates and smaller adult body sizes compared to their counterparts in other parts of the world. Unique characteristics of the BLA foraging habitat (e.g., patchy resources and temperature extremes) appear to require increased diel movements and foraging activity and decreased resting opportunities. These interactions between habitat and turtle behavior not only influence expression of life history traits, but can also increase turtles’ exposure to human activities (e.g., vessel traffic and fisheries bycatch) as they move throughout the area.

Seminoff JA, Whitman ER, Wallace BP, Bayless A, Resendiz A, Jones TT. 2021. No rest for the weary: restricted resting behaviour of green turtles (Chelonia mydas) at a deep-neritic foraging area influences expression of life history traits. Journal of Natural History. 54(45-46):2979-3001.  https://doi.org/10.1080/00222933.2021.1887387.