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Nesting behaviour of the Green turtle at Kosgoda rookery, Sri Lanka

Authors:

EMI Ekanayake,

Department of Zoology, Faculty of Science, Postgraduate Institute of Science, University of Peradeniya, Peradeniya and Turtle Conservation Project, No. 11, Perera Mawatha, Madakumbura, Panadura, LK
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RS Rajakaruna ,

Department of Zoology, Faculty of Science, University of Peradeniya, Peradeniya,, LK
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T Kapurusinghe,

Turtle Conservation Project, No. 11, Perera Mawatha, Madakumbura, Panadura, LK
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MM Saman,

Turtle Conservation Project, No. 11, Perera Mawatha, Madakumbura, Panadura, LK
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DS Rathnakumara,

Turtle Conservation Project, No. 11, Perera Mawatha, Madakumbura, Panadura, LK
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P Samaraweera,

Department of Molecular Biology and Biotechnology, University of Peradeniya, LK
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KB Ranawana

Department of Zoology, Faculty of Science, University of Peradeniya, Peradeniya, LK
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Abstract

Studies on nesting behaviour of turtles provide the most important information on their reproduction by providing estimates of female population size. Kosgoda, located in the southwest coast of Sri Lanka, has a year-round nesting rookery which is visited by five species of sea turtles, the green turtle being the most frequent visitor. Nesting behaviour of the female green turtle was studied at the Kosgoda rookery during a five-year period from August 2003 to July 2008. A total of 1,492 nests of the green turtle were recorded with a mean of 298.4 annual nests. Nesting took place year round, with 66 % of nesting recorded during February to June. The highest and the lowest number of nests were recorded in April and November, respectively. The average clutch size of a female green turtle was 111.5 and the clutch frequency was 2.17. The average annual nesting abundance in the study area was 138.28. Of the 2,297 nesting attempts, 805 were false crawls accounting for a nesting success of 65%. Females nesting at Kosgoda showed nest site fidelity. More than half of the females (54.3%) nested in the same beach twice or more (mean 2.17) during the same nesting season. The highest number of re-nesting recorded was ten and the mean inter-nesting interval was 13.5 days. Of the 519 individuals tagged during the study period, 56 re-visited the same beach for nesting during the subsequent nesting seasons with a mean re-migration interval of 2.56 years. One female visited the same beach three times for nesting during the study period (after 2.67 years and then after 1.83 years). The nesting behaviour of the green turtle at Kosgoda rookery was similar to those at Rekawa, the largest rookery in Sri Lanka, located in the southern coast 130 km away from Kosgoda. Rekawa beach was declared a sea turtle sanctuary in 2006. This study shows that Kosgoda beach also provides a significant nesting site for the green turtle and highlights the need to declare it as a sanctuary.

Key words: clutch frequency; nesting success; re-nesting; re-migration; inter-nesting interval

DOI: 10.4038/cjsbs.v39i2.2997

Cey. J. Sci. (Bio. Sci.) 39 (2): 109-120, 2010

How to Cite: Ekanayake, E. et al., (2011). Nesting behaviour of the Green turtle at Kosgoda rookery, Sri Lanka. Ceylon Journal of Science (Biological Sciences). 39(2), pp.109–120. DOI: http://doi.org/10.4038/cjsbs.v39i2.2997
Published on 21 Apr 2011.
Peer Reviewed

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