Habitat Use and Foraging Ecology of Three Sea Turtle Species Nesting in Northwest Costa Rica

Abstract

Sea turtle species, even when sharing nesting beaches, exhibit distinct at‐sea movements and foraging behavior. At Playa Cabuyal, a sea turtle nesting beach in northwest Costa Rica, we utilized satellite telemetry to reveal the post‐nesting movement of green turtles ( Chelonia mydas , n = 9) alongside carbon and nitrogen stable isotope analysis of skin samples of green ( n = 28), olive ridley ( Lepidochelys olivacea , n = 20), and leatherback ( Dermochelys coriacea , n = 4) turtles. Green turtles (2012–2015) undertook three migratory strategies: moving northward to Nicaragua and the Gulf of Fonseca ( n = 6), remaining resident near Cabuyal in the Gulf of Papagayo ( n = 2), or migrating south to the Gulf of Guayaquil in Ecuador ( n = 1). There was no significant difference in the δ 13 C values of green turtles (mean: −14.7‰, range: −16.8‰ to −12.8‰) and olive ridley turtles (mean: −15.1‰, δ 13 C: −16.6‰ to −14.2‰) suggesting that both species forage across a range of coastal and offshore habitats, while δ 13 C values for leatherback turtles (mean: −15.5‰, range: −15.9‰ to −15.0‰) suggest exclusively offshore habitat use. In contrast, δ 15 N values of green turtles (mean: 16.0‰, range: 13.7 to 17.4‰) were significantly higher than those for olive ridley turtles (mean: 14.2‰, range: 12.3‰ to 15.7‰) suggesting that green turtles may be predominately carnivorous. The notably wide range of δ 15 N values in leatherback turtles (mean: 14.9‰, range: 12.2‰ to 16.8‰) also suggests that this species feeds across many different trophic levels of gelatinous prey. Evidence that the sea turtles nesting on Playa Cabuyal utilize a broad range of foraging areas in the East Tropical Pacific underscores the need for coordinated, multinational conservation efforts for these species.

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