Spatial Ecology of Hawksbill Turtles (Eretmochelys imbricata) Nesting at Gandoca-Manzanillo National Wildlife Refuge, Costa Rica

2019-10-16T16:04:51Z (GMT) by Quintin D Bergman
The beaches in the Gandoca-Manzanillo National Wildlife Refuge (GMNWR) in southeastern Costa Rica are known to host nesting critically endangered hawksbill sea turtles (Eretmochelys imbricata). The spatial ecology and movement behaviors of this nesting population has never been observed. Evaluating the spatial ecology of nesting sea turtles allows for a better understanding of their local movement behavior as well as their large scale oceanic movements that inform conservation needs. Satellite tracks reveal internesting, postnesting migration, and foraging behaviors for four nesting hawksbills from the GMNWR. During the internesting behavior, satellite-tracked hawksbills remained in the coastal waters near the nesting beach for 15 to 55 days before making their postnesting migration. Home-range areas occupied by internesting hawksbills vary between 21.9 and 557.9 km2. Hawksbill internesting high use areas overlapped with the marine boundary of the GMNWR for an average of 29% of time spent inside the refuge. The beginning of all four turtle’s migrations start with a pelagic circular movement away from the coast into the Caribbean Sea before resuming a northern coastal migration pattern. Migration routes varied in length from 662 to 1,486 km and passed through three or four exclusive economic zones of various neighboring nations. Foraging areas of three hawksbills were situated east of Nicaragua and one was found along the northern coast of Honduras, near Roatan. Foraging home-range areas of satellite-tracked hawksbills varied from 205.1 to 696.1 km2. This is the second satellite telemetry study completed on nesting hawksbills in the Costa Rican Caribbean and the first for GMNWR. These results display the use of pelagic and coastal migratory routes for the critically endangered hawksbill. Distant foraging grounds utilized by hawksbills nesting in Costa Rica reveal the importance for the preservation of the Miskito Cays and nearby ecosystems.