ANALYSIS AND COMPARISON OF COASTAL BEACHES FOR NEST SITE SELECTION OF HAWKSBILL TURTLES (ERETMOCHELYS IMBRICATA) IN SINGAPORE

Abstract

Despite being heavily modified and utilized, the beaches in Singapore support tremendous biodiversity and wildlife. In particular, the hawksbill sea turtle (Eretmochelys imbricata) has been perpetually coming onto Singapore’s shores to nest. Hawksbill turtles in Singapore belong to a population in the West Pacific Ocean, where genetic studies have revealed the importance of genetically-distinct microhabitat preferences when choosing a nest site along a beach. Given the lack of studies regarding the nest site selection of hawksbill turtles in the Asia-Pacific region, this study is the first to analyse the influence of several beach parameters that could affect the nest placement of hawksbill turtles across four beaches in Singapore (East Coast Park, Changi Beach, Big Sister’s Island, Small Sister’s Island). These parameters include: beach slope, elevation, width, type of vegetation and sand, and presence of coastal development. A total of 62 points were surveyed, which comprised 28 nesting sites and 34 beach survey points. Results indicate that nests at East Coast Park had a lower elevation than those in Sisters’ Islands, owing to coastal development and coastal retreat from rising sea level. Most nests were also found in vegetated areas. This study also used principal component analysis to interpret multiple environmental variables and suggest that hawksbill turtles in Singapore may follow a sequential threshold hypothesis when selecting nest sites. Comparisons across nesting and non-nesting sites also showed that nesting sites were further away from beachfront lighting. The constant resurfacing of coastal development, which affects the nest site selection of hawksbill turtles, indicate the urgent need for proper nest management and policy decisions in order to conserve these critically endangered species. This would be beneficial for the long-term sustainability of nesting beaches and hawksbill turtles in Singapore.