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Nevertheless, most reports describe the standard mating position where a male will mount a female from behind and hook his fore flipper claws over the anterior rim of the female’s carapace (Booth & Peters 1972; Rostal et al. 1998; Schofield et al. 2006). Due to the paucity of published information regarding sea turtle courtship and mating in general, this note describes an unusual physical interaction between two adult hawksbill turtles, observed offshore of Cousine Island in the Seychelles.

Cousine Island is a small (26 ha) granitic island rising to just over 70 m above sea level and is situated at 4º 20’ 41” S and 55º 38’ 44” E (Samways et al. 2010). On 24 November 2013, I observed an unusual hawksbill turtle interaction during a reef-monitoring dive and recorded it with a high definition underwater video camera. Behavioral observations were made in shallow water (7-10 m depth), approximately 100 m off the island and visibility and water temperature on that day was 15 m and 29 ºC respectively.

Courtship and pre-copulatory behavior was observed from the initiation chase by the male entering the visual range of the female and biting at her carapace (Fig. 1a). The mounting behaviors during this interaction differed from the norm described in the literature in that the male initiated an attempt at courtship and copulation by mounting the female plastron-to-plastron (Fig. 1b). Thus orientated, the male gripped the female’s carapace on the dorsal surface of her carapace with the fore-claws in his front flippers and began biting around and behind the female’s head and neck (Fig. 1b). After further interaction, when orientating themselves vertically in the water (Fig. 1c), the male folded his tail onto the carapace of the apparently receptive female, and attempted to copulate, and appeared to be successful for a short period of time (Fig. 1d).

Figure 1. Hawksbill turtle pair observed offshore of Cousine island beach, 2013-11-24. (a) Male initiating interaction and chase of the female turtle; (b) Male and female interacting, male here biting the neck of the female turtle; (c) Male and female orientated vertically in the water; (d) Male attempting to copulate with the female.

The entire interaction took place over a period of 20 minutes from approximately 12:30 through to 12:50. During this time both the male and female remained completely submerged. After this period of intense interaction both individuals surfaced for air, after which the male again attempted to copulate in the same position, but was unable to successfully mount the female. At no time during the interaction were there any other male turtles present. Although the photographic evidence suggests that mating occurred, it is unlikely as marine turtles, unlike other marine species, may take up to a minimum of 40 minutes to mate successfully (Schofield et al. 2006), as fertilization is internal and females store viable sperm in their oviducts for long periods of time (Gist & Jones 1989).
During a genetic study conducted on Cousine Island by Phillips et al. (2011), it was shown that most male hawksbill turtles mated with only a single female. This behavior could lead to increased aggression in males, and thus precipitate a higher occurrence of males attacking any turtle perceived to be a threat (Mortimer pers. comm. 2014). When taking the above into consideration, the behavior that I observed might best be described as aggressive and pre-copulatory and not the standard for successful copulation between adult hawksbill turtles.

However, detailed, focal observational studies need to be undertaken on the behavior of hawksbill turtles in the Seychelles in order to investigate their behavioral activity more comprehensively. It is becoming increasingly important to understand sea turtle biology in light of global climate change and behavioral studies would benefit from data on the males behavior during the reproduction process and their reproductive success. This type of information would aid in understanding the progression of mating systems in the hawksbill turtle.

Acknowledgements. I thank Dr. J. Mortimer for her expertise and guidance. I also thank Mar. M.F. Keeley, for the opportunity to work and study on Cousine Island.

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