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RESEARCH ARTICLE
Contents Vol 34(3)

Insights into size, seasonality and biology of a nesting population of the Olive Ridley turtle in northern Australia

Scott D. Whiting A E , John L. Long B , Kate M. Hadden B , Anderson D. K. Lauder C and Andrea U. Koch D
+ Author Affiliations
- Author Affiliations

A WWF Australia, PO Box 1268, Darwin, NT 0801, Australia.

B Tiwi Land Council, PO Box 38545, Winnellie, NT 0821, Australia.

C Coastcare NT, PO Box 30, Palmerston, NT 0832, Australia.

D Faculty of Education, Health and Science, Charles Darwin University, NT 0909, Australia.

E Corresponding author. Present address: Marine Biodiversity Group, Department of Natural Resources, Environment and the Arts, Northern Territory Government, PO Box 30, Palmerston, NT 0831, Australia. Email: scott.whiting@nt.gov.au

Wildlife Research 34(3) 200-210 https://doi.org/10.1071/WR06131
Submitted: 10 October 2006  Accepted: 17 April 2007   Published: 6 June 2007

Abstract

The Olive Ridley turtle (Lepidochelys olivacea), classed as endangered in Australia, is one of Australia’s least studied marine turtles and is little known in the south-east Asian region. This is the first detailed study of the nesting biology and ecology of L. olivacea in Australia or south-east Asia, which adds to the regional knowledge of the species and will aid management locally. Daytime surveys of nesting tracks at 14-day intervals in 2004 and irregular surveys in 2005 indicated that the nesting season extended from February to November with peak nesting in April and May. Daily track counts over a 14-day period in April 2004 during peak nesting showed that nesting abundance varied between nights and along the beach. Nightly numbers ranged from 2 to 59 turtles per night over the 10-km beach while, spatially, nesting densities (0.1–6.9 tracks km–1 night–1) varied between sectors. Nesting in this population was solitary, as opposed to the mass nesting behaviour of L. olivacea observed elsewhere in its range, such as in India, Mexico and Costa Rica. The size of nesting L. olivacea was normally distributed with a mean curved carapace length of 69.6 ± 2.3 (s.d.) cm (range = 65.0–75.2, n = 85). During the peak of the nesting season dingoes (Canis lupus dingo) were responsible for the highest egg mortality (over 14%), followed by varanids (Varanus spp., 4.5%) and humans (1.7%). Cyclone Ingrid caused significant egg loss in 2004. Saltwater crocodiles (Crocodylus porosus) were a significant predator of adult nesting turtles.


Acknowledgements

This project was funded partly by the Natural Heritage Trust (Australian Government), the Tony and Lisette Lewis Foundation, WWF–Australia, Tiwi Land Council and Coastcare NT. We thank Cyril Kalippa (Tiwi Land Council Elder and Trustee for Munupi Landowning Group) for access to the area, support and advice, and the Tiwi Land Council for access to the area and support. Ray Chatto (Northern Territory Government) provided preliminary data that helped to select Cape Van Diemen as a study site for this project. We also thank Anthony Kleidon and the staff at the Pularumpi School who provided educational material to the community of Pirlangimpi (Garden Point). All procedures were conducted under approval from the Animal Ethics Committee at Charles Darwin University (A4005) and used wildlife permits from Northern Territory Parks and Wildlife.


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