Monitoring beak movements with an acceleration datalogger: a useful technique for assessing the feeding and breathing behaviors of sea turtles

Abstract

This study was performed to determine whether the attachment of acceleration dataloggers to the lower beaks of loggerhead turtles Caretta caretta could be a useful technique for monitoring their feeding and breathing behaviors. Attaching acceleration dataloggers to the lower beak of turtles allows determination of the pitch of the head from the low frequency component of the acceleration data, and of dynamic movements (e.g. biting) from the high frequency component. In addition, to determine whether the acceleration datalogger could distinguish between different food sources and feeding locations based on acceleration characteristics, we fed the turtles with different types of food (squid rings, fins, and heads that include arms and tentacles) across different locations. Our results demonstrate that the acceleration datalogger was able to detect the lower beak movements of loggerhead turtles, which enabled detection of 99.6 1.1 (SD) % of feeding and 100% of breathing behaviors, with respective false detection rates of 24.8 12.4% and 2.4%. Furthermore, our results demonstrate that it is possible to (1) determine whether feeding on prey requires a strong biting force, and (2) differentiate between feeding at the sea floor and in the water column. Attaching an acceleration datalogger is thus established as a useful technique for monitoring the feeding and breathing behaviors of sea turtles. Future studies employing acceleration dataloggers should provide new insights into the biology of sea turtles and their feeding and diving strategies.