Scientists are fitting goannas with GPS tracking devices as they search for ways to stop them devouring loggerhead turtle eggs.
Researchers are also trialling excluder devices and deterrents - including pepper and red flags - to protect turtle nests at Wreck Rock Beach (situated roughly halfway between Bundaberg and Gladstone).
More than 70 endangered female loggerheads nest at Wreck Rock Beach each year - the second largest mainland nesting site for loggerheads in the South Pacific Ocean.
Foxes used to destroy the majority of nests but baiting has greatly reduced their impact. However, goannas have replaced foxes as a problem. The native lizards could be eating thousands of eggs or hatchlings each year at Wreck Rock Beach - a major blow for an endangered species.
Last year WWF-Australia supported a trial of aluminium cages placed over nests to keep goannas out. They were successful, saving 1200 hatchlings, but each device took 20 minutes to install – not easy for a dedicated but small group of volunteers at a high density nesting beach.
Now the University of Queensland is leading a new, two-year research project to test more user-friendly excluder devices and deterrents and to also learn more about the goannas responsible for turtle nest predation.
WWF-Australia, the Burnett Mary Regional Group, Turtle Care, and Gidarjil rangers are assisting the project. The project was provided nearly $180,000 in funding through the Nest to Ocean Turtle Protection Program, a joint initiative by the Queensland and Australian Governments to address predation of turtle nests.
University of Queensland Scientist Dr David Booth said while it is still early days his team is learning more about goanna behaviour.
“It appears that larger yellow spotted goannas are the first to attack a nest because they have the strength and persistence to dig down through the sand. Once there’s a tunnel to the eggs, smaller yellow spotted goannas and lace monitors also try for an easy meal,” Dr Booth said.
“GPS tracking indicates that yellow spotted goannas are the main culprit. They spend much more time among the beach dunes than lace monitors and no camera trap has ever shown a lace monitor initiating an attack on a nest.
“If we find that a few large yellow spotted goannas are responsible for the majority of nest predation, then relocating these individuals could mean thousands more baby turtles have a chance at life,” he said.
Dr Booth said there had been some reported success overseas spreading pepper over nests as a deterrent or using flags that flap in the breeze to spook predators.
“Unfortunately, initial testing at Wreck Rock Beach has shown that pepper and flags are not particularly successful against goannas. But a simple piece of plastic mesh is proving much more promising,” he said.
“It’s lighter and much easier to transport and install than the aluminium cage and if it is set up properly on top of a nest and covered in sand it is effective at stopping goannas,” said Dr Booth.
WWF-Australia spokesperson Christine Hof said world-wide loggerheads are endangered primarily because they die from entanglement in fishing gear, boat strikes, predation, and ingestion of marine debris.
“In Australia, turtle exclusion devices on nets and fox baiting has eased those problems but now goannas have emerged as a serious issue at the important nesting site of Wreck Rock Beach.
“A healthy Great Barrier Reef needs healthy populations of marine turtles. Helping loggerheads and other marine turtle species recover is a top priority for WWF,” she said.
Long-term volunteers Nev and Bev McLachlan, from Turtle Care, have become increasingly troubled about the number of nests attacked by goannas.
“Our main concern is that something must be done to decrease the amount of predation on our beach so that these beautiful sea creatures are around for all to see,” said Bev.
Saranne Giudice of the Burnett Mary Regional Group said: “Visitors to Wreck Rock may see goannas that are part of the research project marked with numbers or a GPS device, however these do not stay on the animals for long and are not harmful.
“Our region has a crucial role as guardians of a major nesting site for endangered loggerheads. We’ll keep working hard with our partners to give these magnificent creatures a chance to survive into the future,” she said.
WWF-Australia Media Contact:
Mark Symons, Senior Media Officer
0400 985 571