Reproductive Homing and Internesting Behavior of the Green Turtle (Chelonia mydas) at Ascension Island, South Atlantic Ocean

Abstract

Female green turtles (Chelonia mydas) were tagged while nesting on the 32 cove-head beaches distributed in four clusters along the leeward shoreline of Ascension Island. The turtles showed high nesting site fidelity, returning to the same beach cluster during at least 70% of consecutive observed renesting emergences. Stronger site fidelity to beach clusters and also to points within the boundaries of a beach was more evident in emergences separated by less than 7 d (assumed to be repeated attempts to lay one clutch of eggs) than in nestings separated by longer time intervals, involving separate egg clutches. These differences correlate with predictable patterns of behavior observed in females, the movements of which were visually tracked during their internesting intervals. After successful oviposition, most of the tracked females traveled to a shallow area off the northwest coast of the island. Those that did not lay eggs remained in the vicinity of the beach just abandoned, traveling back and forth in nearshore waters until daylight when they moved into deeper water. The rates, patterns and periodicities of travel by Ascension turtles in their internesting habitat after successful and aborted nestings are compared with those of internesting female turtles at other breeding grounds; possible explanations for observed differences are discussed.