| dc.description.abstract | The leatherback sea turtle (hereafter referred to as LB), which is monotypic in the family Dermochelyidae, is morphologically and physiologically distinct from other six extant sea turtle species. Despite its worldwide distribution and ancient lineage, it is one of the least understood marine turtles because of its pelagic life. The goal of this study was to use miniature, animal-borne video and data recorders and satellite telemetry to monitor diving and foraging behavior and movements of LB during the internesting interval on St. Croix in the U.S. Virgin Islands. I tested two hypotheses: 1) foraging is rare and opportunistic during the internesting interval, and 2) the internesting interval is an antipredator strategy. The results show that LB make two types of dives: Shallow Transit (ST) and Deep Transit (DT) dives. ST dives were short, shallow and associated with slow subsurface swimming to reduce drag. DT dives involved gliding and were moderately deeper than ST dives with a longer distance traveled at the same slow speed. LB spent 94% time at sea making ST and DT dives with short surface resting periods, but there was no indication of prolonged periods of resting or sleep. Six species of gelatinous prey were identified. Reduced foraging effort indicated fasting during nesting season (i.e., capital breeding strategy). There was no indication of behavioral thermoregulation. Assuming LB fast during the nesting season, the energy expended while at sea for the entire internesting interval would be equivalent to the catabolism of 26.3 kg of fat (39 kg fat including egg production). LB are at risk of predation from sharks once they leave the beach, most likely from tiger sharks based on scars, wounds, and missing flippers. When attacked, their response was instantaneous, robust, and involved evasive swimming at an elevated speed with rapid rotation, steep descent and ascent, and lateral inversion. Most shark encounters were short (< 5 min), which indicates that defensive behavior is effective, although this behavior cannot eliminate injury and death. Shark attacks were most frequent (3-fold) when LB were < 6 km from St. Croix compared to > 6 km offshore. If LB had remained < 6 km from shore for the entire interesting interval, they potentially would have experienced 48% more shark attacks. Therefore, offshore internesting trips appear to be a strategy to reduce shark encounters (i.e., avoidance behavior) while the next clutch of eggs develops. | en |
