ESR 27:265-276 (2015)  -  DOI: https://doi.org/10.3354/esr00672

Seasonality, abundance, and fifteen-year trend in green turtle nesting activity at Itsamia, Moheli, Comoros

J. Bourjea1,2,*, M. Dalleau3, S. Derville3,4, F. Beudard3,5, C. Marmoex3, A. M’Soili5, D. Roos1, S. Ciccione3, J. Frazier6

1Institut Français de Recherche pour l’Exploitation de la Mer (Ifremer), Délégation Océan Indien, Rue Jean Bertho, BP 60, 97822 Le Port Cedex, Ile de La Réunion, France
2University of Reunion Island, FRE3560 INEE-CNRS, 15 Avenue René Cassin, BP 7151, 97715 Saint Denis, La Réunion, France
3Kélonia, l’Observatoire des Tortues Marines de La Réunion, 46 rue du Général De Gaulle, 97436 Saint Leu, La Réunion, France
4Ecole Normale Supérieure de Lyon, Département de Biologie, 15 parvis René Descartes, 69007 Lyon, France
5Association pour le Développement Socio-Economique d’Itsamia (ADSEI), BP 36, Fomboni, Moheli, Comoros
6Division of Amphibians and Reptiles, Department of Vertebrate Zoology, National Museum of Natural History, Smithsonian Institution, PO Box 37012, Washington, DC 20013-7012, USA
*Corresponding author:

ABSTRACT: Nesting green turtles Chelonia mydas were studied at Moheli Island, Union of Comoros, southwestern Indian Ocean (SWIO). Five contiguous beaches near Itsamia village, in the southeastern part of the island, were monitored daily for nesting activity from January 1999 to June 2007 and irregularly between August 2009 and December 2014; nesting success was recorded from 2000 to 2006. Nesting occurred year-round and peaked in the austral winter, from March through August, with the highest values in May. During the 7 yr period when nesting success was recorded, 63164 successful nestings were reported, and the total was 69630 when estimates of missing data were included. The average rate of nesting success was 0.49 (SD = 0.04, n = 7). Using the estimate of 3.03 successful nestings per female per season, the estimated number of nesting females per year varied from 924 in 2000 to 5827 in 2005. There was marked growth in nesting activity over the beginning of the study period, as indicated by seasonal decomposition of time series by loess and generalized additive mixed model analyses, with an increase of 226% from 1999 to 2006 and evidently a leveling off of nesters between 2007 and 2014. The Itsamia beaches have one of the largest nesting populations, with a higher rate of increase than any other site in the SWIO. Long-term protection of the beaches and offshore waters by the Itsamia community, despite several years of intense exploitation by outsiders, is reasoned to be the primary explanation for these remarkable figures.


KEY WORDS: Green turtle · Nesting · Seasonality · Trend · Comoros · Moheli


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Cite this article as: Bourjea J, Dalleau M, Derville S, Beudard F and others (2015) Seasonality, abundance, and fifteen-year trend in green turtle nesting activity at Itsamia, Moheli, Comoros. Endang Species Res 27:265-276. https://doi.org/10.3354/esr00672

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