Nesting female leatherback turtles, Dermochelys coriacea Vandelli, 1761, are ungainly and vulnerable to predation, stranding and physiological stress, dangers encountered repeatedly in a nesting season. Minimising these risks must be balanced against optimising investment in nest site selection, excavation, re-filling, and concealment of their egg clutches. We investigated the relative investment in the different phases of nesting in leatherback turtles by recording the duration of, and respiratory frequency during, each phase. Nest excavation and the final sand scattering (usually termed 'camouflage' or 'disguise') phases were the longest in duration. By combining the relative durations of nesting phases with literature estimates of oxygen consumption, we found that these may be the most expensive phases energetically, sand scattering in particular. Leatherback turtles follow convoluted paths during the sand scattering phase, which were mapped and measured. They disturb large areas (mean 30.3 + 11.1 m 2 , maximum 57 m 2 ), the centroids of which were always offset from the nest itself. Interestingly, in none of 26 nestings observed did the centre line of females move over the nest itself. Nesting leatherbacks therefore invest heavily in obscuring the egg clutch, and the pattern of their movements in doing so suggests decoy behaviour.
The Wildlife Health Bridge was established in 2009 with the aim of improving the expertise and knowledge base of wildlife health professionals in biodiverse low- and middle-income countries. The Wildlife Health Bridge centres around partnerships among educational institutions: the Zoological Society of London, the Royal Veterinary College, the University of Edinburgh’s Royal (Dick) School of Veterinary Studies, the Wildlife Institute of India, and the University of Melbourne Veterinary School. The Wildlife Health Bridge provides quality education in wildlife health, ecosystem health, and wildlife biology, facilitates the interchange of students between collaborating countries for research studies and provides a global graduate network of wildlife health professionals. In addition to established Masters’ level wildlife health training programmes run by the partner organisations, the Wildlife Health Bridge has developed a collaborative field-based course, Interventions in Wild Animal Health, provided annually in India since 2016, which has trained 138 veterinarians to date, enhancing local and international capacity in managing emerging wildlife health issues and building global professional linkages. The Wildlife Health Bridge’s Wild Animal Alumni network facilitates networking and exchange between Wildlife Health Bridge institutions and graduates, with over 701 members from 67 countries, half of which are biodiverse low- and middle-income countries. Collaboration between educational institutions has enabled new ideas and ongoing developments in the delivery of materials and learning outcomes. The Wildlife Health Bridge is building global capacity in trained wildlife health professionals, through educational programmes and a synergised network, with the aim of impacting conservation practice to benefit human, domestic animal and wildlife health.
After laying their eggs and refilling the egg chamber, sea turtles scatter sand extensively around the nest site. This is presumed to camouflage the nest, or optimize local conditions for egg development, but a consensus on its function is lacking. We quantified activity and mapped the movements of hawksbill (
Eretmochelys imbricata
) and leatherback (
Dermochelys coriacea
) turtles during sand-scattering. For leatherbacks, we also recorded activity at each sand-scattering position. For hawksbills, we recorded breathing rates during nesting as an indicator of metabolic investment and compared with published values for leatherbacks. Temporal and inferred metabolic investment in sand-scattering was substantial for both species. Neither species remained near the nest while sand-scattering, instead moving to several other positions to scatter sand, changing direction each time, progressively displacing themselves from the nest site. Movement patterns were highly diverse between individuals, but activity at each sand-scattering position changed little between completion of egg chamber refilling and return to the sea. Our findings are inconsistent with sand-scattering being to directly camouflage the nest, or primarily for modifying the nest-proximal environment. Instead, they are consistent with the construction of a series of dispersed decoy nests that may reduce the discovery of nests by predators.
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