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Figure 1. Location of Matapalo beach, Guanacaste, Costa Rica. Dotted lines in Sardinal District are highways.

Matapalo Beach is easily accessible by car; it allows for people to visit the beach during the night to collect eggs illegally. According to Blanco & Santidrián (2011), 50% of green turtle nests were poached during their survey at Matapalo beach. This beach is not a wildlife protected area managed by the government and it has moderate beachfront development as with many nesting beaches in Guanacaste (Blanco & Santidrián 2011). Currently, beachfront development comes mainly from the Riu Hotel Guanacaste and Riu Palace; these two hotels have replaced native vegetation and manage a beachfront that is approximately 200 m long.

Figure 2. Number of activities classified as successful nests (light blue) or false crawls (dark red) observed for Pacific green turtles nesting at Matapalo Beach (n = 264).

To the best of our knowledge, this is the first study about the nesting activity of adult female Pacific green turtles at Playa Matapalo. The beach was patrolled at night for 100 days, from 7 September 2011 to 7 February 2012. According to Cornelius (1986), from October to March is the peak of the nesting season for the Pacific green turtle in Costa Rica. Nesting activity was surveyed mainly from 6 pm until midnight and the eggs were collected in order to relocate them if possible. The beach was patrolled every morning to count nesting activity (SWOT Scientific Advisory Board 2011). Each nesting activity was classified as a false crawl or a nest; we recorded 264 nesting activities (Fig. 2). Of these activities, 117 were successful oviposition events/ nests (44%). Sixty-four nests were left in situ (55%) and 53 nests were relocated (45%). Unfortunately, 31 nests left in situ were poached (48%). No relocated nests were poached. We observed 147 false crawls corresponding to 56% of the total activity (Fig. 2). The mean and standard deviation (SD) for the data were obtained according Sokal & Rohlf (1980). The average number of eggs per clutch for both relocated and in situ nests was 60 ± 21 SD eggs (n = 48). Here we report the percentage of hatching success, emergence success and number of hatchlings for relocated nests. Hatching success was 84% ± 20 SD (n = 28) and emergence success was 69% ± 26 SD (n = 24); 1,804 hatchlings were produced from 38 nests. Continued monitoring of this beach and additional information collection about the nesting ecology of Pacific green turtles is highly recommended. Furthermore the use of flipper tagging to estimate the number of females nesting would improve our knowledge about this nesting population. Also, it is very important to establish a hatchery with good protection to decrease poaching and increase environmental awareness. Any future sea turtle conservation initiative at Matapalo Beach must consider the current effect of beachfront development, in order to determine those impacts caused by land use change on sea turtle nesting activity.

Acknowledgments. I thank Riu Hotel Guanacaste for providing logistical support for this research. Research was performed under permit ACT-OR-DR-117, from Tempisque Conservation Area (ACT), Sistema Nacional de Areas de Conservación (SINAC), and the Ministry of Environment and Telecommunications (MINAET).

BLANCO, G. & M. SANTIDRIÁN. 2011. La tortuga marina negra de Guanacaste amenazada de extinción por prácticas humanas. Ambientales 41: 19-26.

CORNELIUS, S.E. 1986. The Sea Turtles of Santa Rosa National Park. Fundación de Parques Nacionales Costa Rica, Costa Rica. 64 pp.

NATIONAL MARINE FISHERIES SERVICE AND U.S FISH AND WILDLIFE SERVICE. 1998. Recovery plan for U.S Pacific populations of the East Pacific Green Turtle (Chelonia mydas ). National Marine Fisheries Service, Silver Spring, Maryland. 50 pp.

SEMINOFF, J.A. 2004. Chelonia mydas . IUCN Red List of Threatened Species. Version 2013.1. <http://www.iucnredlist.org>.

SOKAL, R. & J. ROHLF. 1980. Introducción a la Bioestadística. Reverté S.A, Barcelona. 362 pp.

SWOT Scientific Advisory Board. 2011. The State of the World’s Sea turtles (SWOT) Minimum Data Standards for Nesting Beach Monitoring. 28 pp. <http://www.seaturtlestatus.org/data/standards>