Abstract:Little is known about the effects of jaguars on the population of marine turtles nesting in Tortuguero National Park, Costa Rica. This study assessed jaguar predation impact on three species of marine turtles (Chelonia mydas, Dermochelys coriacea and Eretmochelys imbricata) that nest in Tortuguero beach. Jaguar predation data was obtained by using two methodologies, literature review (historical records prior the year 2005) and weekly surveys along the 29 km stretch of beach during the period 2005-2013. Our results indicated that jaguar predation has increased from one marine turtle in 1981 to 198 in 2013. Jaguars consumed annually an average of 120 (SD= 45) and 2 (SD= 3) green turtles and leatherbacks in Tortuguero beach, respectively. Based on our results we concluded that jaguars do not represent a threat to the population of green turtles that nest in Tortuguero beach, and it is not the main cause for population decline for leatherbacks and hawksbills. Future research should focus on continuing to monitor this predator-prey relationship as well as the factors that influence it so the proper management decisions can be taken. Rev. Biol. Trop. 63 (3): 815-825. Epub 2015 September 01.
Key words:Chelonia mydas, Dermochelys coriacea, Eretmochelys imbricata, marine turtles, Panthera onca, predator-prey interaction, Tortuguero National Park.Predator-prey interactions play a critical role in the dynamics of the ecosystems (Heithaus, Wirsing, Thomson, & Burkholder, 2008). It is well known that predators can have a direct effect on prey due to consumption of prey individuals (Nelson, Matthews, & Rosenheim, 2004;Heithaus et al., 2008). However, predators can also induce behavioral changes in prey which may lead to shift in activity patterns, reduction in foraging time or spatial and temporal redistribution, among others (Nelson et al., 2004;Heithaus et al., 2008, Valeix et al., 2009Fitzpatrick et al., 2012). Nonetheless, the effect of predators on adult marine turtles has been overlooked since this interaction can be difficult to observe and quantify (Heithaus et al., 2007;Hays, 2008;Fitzpatrick et al., 2012;Bornatowski, Heithaus, Batista, & Mascarenhas, 2012). Heithaus et al. (2008) suggested that predators of adult marine turtles can influence turtle population sizes in spite of low predation rates. Pitman and Dutton (2004) predation upon marine turtle populations in the Mediterranean sea is unknown but probably extremely small compared to other sources of mortality (e.g. anthropogenic causes). Ortiz, Plotkin and Owens (1997) indicated that American crocodile (Crocodylus acutus) predation on the olive ridley sea turtles (Lepidochelys olivacea) have little or no effect on the nesting population at Playa Nancite in Costa Rica. They also highlighted that this interaction may enhance the survival of the local population of crocodiles. Heithaus et al. (2007) also emphasized that the loss of marine turtle predators could result in a negative impact in the ecosystem dynamics.Although jaguar (Panthera onca) predati...