Nesting preferences of hawksbill (Eretmochelys imbricata) and leatherback (Dermochelys coriacea) turtles in the Gandoca Manzanillo National Wildlife Refuge, Limón, Costa Rica

Abstract

The Caribbean region of Costa Rica is an important feeding, mating, nesting and spawning area for sea turtles, which exhibit site preference in beaches to build their nests. This study attempts to review the nesting pattern of sea turtles Dermochelys coriacea and Eretmochelys imbricata in the Gandoca sector of the National Wildlife Refuge Gandoca Manzanillo, Limón, Costa Rica, to propose management actions. Between February and August of 2011 and 2012 night patrols were conducted between 8:00 p. m. to 4:00 a. m., in five sectors of beach, across Punta Mona and the Sixaola river mouth recording direct observations and tracks of nesting turtles only. A total of 1005 individuals of D.coriacea, 47 of E.imbricata and 6 of Chelonia mydas were recorded. Due to sampling size C.mydas was not taken into account for analyses. Leatherback nesting activity peaked between March and July in both years. Hawksbill from May to June in 2011 and June to August in 2012. Preferences were observed regarding the position in the beach used for nesting. Leatherbacks used the middle section of the beach mainly, while the hawksbill use mostly the bottom to nest (t = 17.2525). The leatherback seemed to use more frequently the C sector, however, no differences in the use of the sectors between turtles were found. It is concluded that both species have preferred nesting areas. Hawksbill uses more the bottom beach area near the shoreline while leatherback uses the middle area more. Also the leatherback turtles use interchangeably different sectors of the studied beach.