Habitat Use and Diet of Juvenile Eastern Pacific Hawksbill Turtles (Eretmochelys imbricata) in the North Pacific Coast of Costa Rica

摘要

The hawksbill turtle (Eretmochelys imbricata) is critically endangered throughout its global range and is particularly threatened in the eastern Pacific, a region where our knowledge of the ecological traits is very limited. Understanding habitat preferences of hawksbills at different life stages is necessary to create effective local and regional conservation strategies. We studied habitat use and the diet of juvenile hawksbill sea turtles at Punta Coyote, a rocky reef located along the Nicoya Peninsula on the north Pacific coast of Costa Rica, along the northern boundary of the Caletas-Ario National Wildlife Refuge. We tracked 12 juvenile hawksbills (36-69-cm curved carapace length) with acoustic transmitters to study their habitat use. Turtles were on the rocky reef more frequently than the sandy bottoms (x~2_1 = 29.90, p = 0.00). The 95% fixed kernel density home range analysis revealed high-intensity use of the rocky reef, where hawksbills mainly dove in shallow waters (7.6 ± 3.3 m). Less than 5% of the 95% home range area overlapped with the Caletas-Ario National Wildlife Refuge. Hawksbills fed mainly on 2 invertebrate species regardless of season: a sponge (Geodia sp.) (mean volume = 67%) and a tunicate (Rhopalaea birkelandi) (mean volume = 51%). Our surveys along the Nicoya Peninsula suggested that use of rocky reefs by juvenile hawksbill turtles was common. To protect juvenile hawksbills in the study area, we recommend that this site be granted official protection status as part of the Caletas-Ario National Wildlife Refuge. We also suggest studying other discrete rocky reefs along the Nicoya Peninsula to determine critical habitats for the hawksbill turtle to improve conservation and management policy.