Temporal distribution and periodicity in hawksbill turtles (Eretmochelys imbricata) nesting at Cousin island, Republic of Seychelles, 1971-1997

  • Published source details Mortimer J. A. & Bresson R. (1999) Temporal distribution and periodicity in hawksbill turtles (Eretmochelys imbricata) nesting at Cousin island, Republic of Seychelles, 1971-1997. Chelonian Conservation and Biology, 3, 318-325.


The largest hawksbill turtle Eretmochelys imbricata breeding population remaining in the western Indian Ocean is found on the Seychelles archipelago, where about 1,230-1,740 females were estimated to nest annually in the early 1980s. Since then, however, breeding numbers declined on most beaches because of hunting of nesting females. In 1994, the turtle harvest was completely banned on the Seychelles. An exception to the post-1980's hawksbill decline was the population on the island of Cousin which gradually grew in size in response to a conservation programme. This project is described here.

Study area: An exception to the widespread post 1980s breeding decline in the population of hawksbill turtles Eretmochelys imbricata in the Seychelles was on Cousin Island Special Reserve. Before 1970 most of the turtles nesting on Cousin were killed by people for food. BirdLife International (then the International Council for Bird Preservation) stopped the taking of turtles in 1968 when it purchased the island, which was designated a Nature Reserve. Full legal protection was provided in 1974 when the island was designated a 'Special Reserve', and a marine protected area was established (extending up to 400 m from the shoreline out to sea) around Cousin.

Turtle monitoring: Monitoring was introduced in 1972 and continues under Nature Seychelles, the managers of the Reserve since 1998. It has become one of the world's longest (if not the longest) running hawksbill monitoring programme. Nesting beaches are protected, monitored and kept free of debris that may prevent access to nesting females and be barriers to turtle hatchlings as they make their way down to the sea. Poachers are kept out of the marine reserve thus protecting gravid females as well as mating pairs, as they approach the shoreline.

During the turtle nesting season the wardens regularly patrol the beaches. This is vital since hawksbill turtles in Seychelles nest during daylight hours, unlike the situation in other countries. Visitors are kept at safe distances to observe nesting females. Nests are all flagged with standardized markers. Since Cousin is free of introduced predators such as rats Rattus spp., dogs Canis familiaris, cats Felis catus and pigs Sus scrofa that could interfere with the nests or hatchlings, there is only natural (and predicted) mortality.

The monitoring is based on standard techniques and data entry forms used at all sites in Seychelles and refined by Dr. Jeanne Mortimer. Regular beach patrols, tagging new turtles, noting existing tag numbers and other biological parameters, number of emergences, successful nesting and so forth are some of the activities undertaken.

Anti-poaching measures: Poachers are kept out of the marine reserve through various ways. As Cousin has been a reserve for over 30 years the designation is well know. Economic benefits from a thriving ecotourism business on Cousin by local people also deter poaching. Special buoys have been set in the sea demarcating the reserve. The wardens approach any suspicious looking boats and query the activities. The staff have the powers to arrest and also to seize vessels, equipment and any evidence.

The Reserve now hosts what is considered to be the single most important nesting site for hawksbill turtle in the western Indian Ocean. Nesting activity, since 1972 has almost quadrupled. From lows of less than 30 nesting females annually in 1972, the population had grown to at least 140.

Many problems have been encountered including lack of scientific capacity in Seychelles and inadequate interest from the international scientific community for further research, lack of motivation on the part of staff, lack of funding, poaching outside the reserve, and constraints to do with the police and courts.

Conclusions: The experience on Cousin shows that protection of nesting beaches and of female turtles coming in from the sea to nest is an effective way of conserving and enhancing the hawksbill population. This model programme on Cousin has shown the way forward and since the 1990's, management on other islands is ongoing, as well as the Seychelles government taking protection of nesting sea turtle beaches seriously.

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