COMPARING THE BEHAVIOR OF EAST PACIFIC GREEN TURTLES FROM TWO NEIGHBORING BEACHES IN PACIFIC COSTA RICA

CHELSEA CLYDE-BROCKWAY; STEPHEN J. MORREALE; FRANK V. PALADINO; NATHAN ROBINSON; JAMES R. SPOTILA; GABRIELA S. BLANCO; PILAR SANTIDRIÁN TOMILLO

Las Vegas

Congreso; 37th International Symposium of Sea Turtle Biology and Conservation; 2017

Green turtle inter-nesting behavior is examined on a site-by-site basis, with each nesting beach being treated as a unique individual. This is time consuming and expensive, especially when addressing a species that might not have time for site-specific analysis to generate conservation management plans. If we employ comparative studies we can generalize turtle behavior and begin to predict what habitats are necessary without deploying costly transmitters on turtles at each individual nesting beach. We hypothesize that due to inconsistent distribution of resources spatially and temporally; turtles will conserve energy during the inter-nesting interval and display similar behavior regardless of nesting beach. We predict that the average inter-nesting movement of green turtles will be similar between beaches and years. We used satellite telemetry to investigate this prediction using two nesting populations of East Pacific green turtles that nest 50 km apart on beaches in Pacific Costa Rica (playas Cabuyal, CAB, and Nombre de Jesús, NDJ). Data collection began in 2007 at NDJ and continued through 2009; data collection at CAB began in 2012 and continued through 2015. We successfully recorded inter-nesting movements for 22 turtles (n=9 NDJ, n=13 CAB) and dive behavior was collected on eight turtles (n=3 NDJ, n=5 CAB). The turtles used for this study were of a similar size, CCL of 82 ? 89.5 cm for NDJ and 82.2 ? 91.6 cm for CAB, and had inter-nesting intervals that were within the range expected for the species, 12±1.4 days for NDJ and 15.4±2.9 days for CAB. We analyzed area use using a kernel density analysis in ArcGIS, and found that the contours of home range were the same between the beaches, however individual movements, using log transformed track length, were significantly different between beaches (ANOVA, F1,20=15.06 P=0.001; R 3.3). Summary dive data indicate that 80% and 43% of dives remained in the top 5 meters of the water column for NDJ and CAB, respectively. Dive durations ranges between 0 and 60+ minutes, with 88% and 92% of dives being 30 minutes or shorter for NDJ and CAB, respectively. The major difference between the beaches is how turtles used the surface water, being defined as 2 meters or shallower; turtles from NDJ had 33% of dives being surface dives, while CAB only had 8%. All turtles showed the same daily activity trends, with diurnal dives being deeper than nocturnal dives. Core area use of nesting East Pacific green turtles was not different between the two beaches, even though individual movement was determined by beach. This could be because the two nesting beaches are in fact the same population of turtles, although we know there were no repeated individuals in this study, or because the behavior of East Pacific green turtles is similar regardless of the nesting beach. If the latter is true, then we can estimate required protected area of East Pacific green turtles in Costa Rica without individual site analysis, saving time and money.