Hawksbill turtle monitoring in Cousin Island Special Reserve, Seychelles: an eight-fold increase in annual nesting numbers

Allen, ZC, Shah, NJ, Grant, A, Derand, GD and Bell, DJ (2010) Hawksbill turtle monitoring in Cousin Island Special Reserve, Seychelles: an eight-fold increase in annual nesting numbers. Endangered Species Research, 11 (3). pp. 195-200. ISSN 1863-5407

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Abstract

Results of hawksbill turtle Eretmochelys imbricata nest monitoring on Cousin Island, Seychelles, indicate an 8-fold increase in abundance of nesting females since the early 1970s when the population was highly depleted. From 1999 to 2009, the population increased at an average rate of 16.5 turtles per season. Females were individually tagged, and nesting data were derived from indirect evidence of nesting attempts (i.e. tracks) and actual turtle sightings (56 to 60% of all encounters). Survey effort varied over the years for a variety of reasons, but the underlying trends over time are considered robust. To overcome biases associated with variable survey effort, we estimated population changes by fitting a Poisson distribution to data on numbers of times each individual was seen at this breeding site in a season. This was used to estimate unseen individuals, and hence the total number of nesting females each season. The maximum number of individuals emerging onto Cousin Island to nest within a single season was estimated to be 256 (2007 to 2008) compared to 23 in 1973. Tag returns indicate that many turtles nest on both Cousin and Cousine Islands (2 km apart), and that some inter-island nesting also occurs between Cousin and more remote islands within the Seychelles.

Item Type: Article
Faculty \ School: Faculty of Science > School of Biological Sciences
Faculty of Science > School of Environmental Sciences
University of East Anglia > Faculty of Science > Research Centres > Centre for Ecology, Evolution and Conservation
University of East Anglia > Faculty of Science > Research Groups > Environmental Biology
University of East Anglia > Faculty of Science > Research Groups > Resources, Sustainability and Governance
University of East Anglia > Faculty of Science > Research Groups > Marine and Atmospheric Sciences
University of East Anglia > Faculty of Science > Research Groups > Organisms and the Environment
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Depositing User: Deborah Clemitshaw
Date Deposited: 11 Feb 2011 10:02
Last Modified: 04 Sep 2018 16:31
URI: https://ueaeprints.uea.ac.uk/id/eprint/21295
DOI: 10.3354/esr00281

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