ESR 18:27-34 (2012)  -  DOI: https://doi.org/10.3354/esr00436

ABSTRACT: The use of off-road vehicles (ORVs) on sandy beaches creates ruts in the sand that may interfere with the beach dispersal of sea turtle hatchlings. The present study investigated the influence of simulated ORV ruts of 3 depths (5, 10 and 15 cm) on the success and speed of green sea turtle Chelonia mydas hatchling dispersal. Almost all hatchlings (91%) were unable to traverse a single 15 cm rut, indicating that ruts of this depth are particularly detrimental to hatchling dispersal. Hatchlings had greater success traversing the 5 and 10 cm ruts, although they spent 2.6 and 18.6 times longer to get through a single rut, respectively (compared to the flat sand control path). It took progressively longer to get through subsequent ruts, and 99 and 53% of the hatchlings crawled along the 10 and 5 cm ruts, respectively, instead of attempting to crawl out of them. It was estimated that if hatchlings had to traverse 100 ORV ruts during dispersal, it would take 1.9 and 25.1 h for 5 and 10 cm deep ruts, respectively. The results from the present study indicate that green sea turtle hatchlings would spend considerable time navigating through ORV ruts, even as shallow as 5 cm, resulting in increased exposure to predation, dehydration and energy expenditure during this initial stage of dispersal.

KEY WORDS: Tyre ruts · 4-wheel drive · Off-road vehicle · ORV · Recreational activity · Nesting · Endangered species · Turtle · Seafinding · Hatchling