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We report an opportunistic observation of an unsuccessful nesting attempt by the Critically Endangered hawksbill turtle (Eretmochelys imbricata) (Mortimer & Donnelly 2008), at Côco Beach on Príncipe Island (1° 41 N; 7° 24 E). The island, which is located on the Gulf of Guinea in West Africa, was recently nominated as a UNESCO Biosphere Reserve and today high level tourism investments are being planned and implemented. Côco Beach extends 611 m and is backed by a resort complex where artificial lights (bungalow balcony lights and 1-m light poles, all oriented toward the sea), armoring (concrete bungalows and 30-cm high garden curbstones which impede nesting) and ornamental grass are distributed along ca. 150 m of the northern fraction of the beach. Otherwise, this portion of the beach represents the best suitable nesting habitat for turtles. Connected to the resort by an illuminated wooden bridge there is a small islet where the restaurant is located. Although lights were turned off nightly at midnight, most of the turtle emergences occur before that time according to technicians from the local turtle program (H. Carvalho, pers. comm.). Sea turtle nesting is not monitored on that beach but animals are protected from poachers since only resort staff and tourists have access to it.

Figure 1. Egg chamber abandoned by female hawksbill. Behind the motorcycle is the light pole that attracted the disoriented hawksbill.

In this disorientation event, the female hawksbill was first observed emerging before sunset at 17:45 on 23 January 2010. After encountering a curbstone (~30 cm high), that delimited a small garden surrounded by grass, the turtle started digging an egg chamber. However, the nesting attempt was abandoned at 18:20, before the egg chamber was completed (Fig. 1). From observations of the inside of the egg chamber, the most probable cause for the abandonment was the presence of roots and very compact sand. The turtle then moved inland toward the main source of light (a pole with a strong light) where it remained inactive for 25 min, apparently disoriented and without knowing what to do (Fig. 2). At 18:45 the turtle moved parallel to the beach and then after the resort lights were turned off at our request, she managed to orient herself in the direction of the ocean and moved through the parking lot until she encountered a group of curbstones at 18:51 (Fig. 3). The hawksbill then turned inland and moved in the direction of two resort guards with flashlights. Once the flashlights were extinguished, the turtle again moved toward the ocean and at 18:55, she successfully climbed over the curbstone obstacle. At this point the turtle was held for tagging and genetic sampling (minimum curved carapace length = 80 cm; flipper tags: TTY469; TTY468) by request of a foreign researcher who was on the island to collect hawksbill blood samples. Upon release, the female again started to move inland, disoriented by the lights that were already back on for the functioning of the resort (it was necessary to restart the diesel generator for power). We then helped turn the turtle toward the ocean by blocking the lights and directing its path with our bodies.

Figure 2. Nesting female hawksbill attracted to the light pole after abandoning its nesting attempt (it remained at that location for 25 min).

On 25 January 2010, two nights later, another abandoned egg chamber was observed in the resort area. The following night, 26 January 2010, the previously tagged hawksbill emerged but was turned over on its carapace by resort guards before attempting to nest. For years, foreign research personnel and conservation projects methodologies relied on paying for turtles, so this is a frequent practice that we do our best to correct. However, in this instance the turtle was released and it returned immediately to the ocean. When sea turtles are deterred from nesting they may be forced to select less suitable nest sites or they may shed their eggs at sea (Witherington & Martin 2003). In fact, several turtle eggs were sighted and reported by spearfishers on the reef in front of Côco Beach during the subsequent nesting season. Also, in November 2012, another hawksbill was observed emerging during the day in the resort area and according to the coordinator of a foreign turtle program, it behaved in a similar way to the turtle reported in this note. The 2012 turtle aborted an egg chamber near the grassy border and then walked around the resort looking for a nest site; it was unsuccessful in finding a new site. However it managed to find the sea before nightfall (J. Hancock pers. comm.).

Figure 3. Curbstones dividing the parking lot from the beach (on the left side of the central curbstone, the dirt mark left by the hawksbill is visible).

During our visits and stays at the resort, we frequently observed the unnecessary use of lighting on balconies and in employee accommodations. These lights were visible from the beach. The illumination of the bridge that connects the restaurant islet to the resort are visible from the resort beaches and from the ocean; in the absence of wave clues, lights may impact the dispersal of swimming hatchlings over distances >1.5 km (Kamrowski et al. 2012).

We delivered published manuals on minimizing light pollution on sea turtle nesting beaches to the resort responsible and prepared a best practices guide for the staff and visitors on simple ways to reduce impacts, but we have no knowledge if it is being used and a recent visit (December 2012) revealed that lights and armoring had not changed. Of all the anthropogenic threats that sea turtles face, light pollution may be among the most manageable. Management, rather than prohibition, is the most realistic conservation policy for developed sea turtle nesting beaches (Witherington 1999). Witherington (1992) pointed out that mercury vapor lamps and other broad-spectrum lighting types, such as incandescent, metal halide, and conventional fluorescent lamps, could all perturb nesting. The author also suggests that when lighting cannot be eradicated during the nesting season, low-pressure sodium vapor lamps should be used as substitutes. For a comprehensive list of light management techniques for sea turtle nesting beaches, see Witherington & Martin (2003).

A nesting beach survey conducted during the 2009/2010 nesting season at the Island of Príncipe, estimated that only 2 hawksbill nests are laid each year at Côco Beach while 80 are laid at the other 50 sandy beaches of Príncipe (Ferreira et al. unpublished data). Reducing light pollution on Côco Beach during the nesting season could benefit both the turtles and the resort. Also, the removal of bungalows and gardens that cover the otherwise suitable nesting habitat, along with the naturalization of that area (though expensive), would have the most positive effects on nesting. Visitors could be made aware that they are contributing to the protection of an endangered species and nesting sea turtles would have a potentially suitable and poacher-free beach. We recommend that as development increases along the Príncipe coastline, impacts of armoring and light pollution on sea turtles and other animals should be anticipated and managed through the implementation of mitigation strategies.

Acknowledgements: We are grateful to the Príncipe Island local government and authorities, to the anonymous reviewers of the manuscript and to the Portuguese Foundation for Science and Technology by providing RLF with a PhD fellowship (SFRH/ BD/73947/2010).

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