Red flags and hot chilli powder do not stop the yellow-spotted goannas from raiding nests on Wreck Rock beach, Queensland

Scientists are working to find out ways to prevent goannas devouring the eggs of endangered loggerhead turtles after deterrents such as red flags and attempts to smother nests with hot chilli powder failed.

Researchers have focused their efforts at Wreck Rock beach, between Bundaberg and Gladstone, in Queensland. The beach is the second largest nesting site for loggerhead turtles in Australia but there is a growing problem of goannas feasting on turtle eggs.

It is estimated goannas raid about half the 500 nests laid by turtles on the beach between November and February. Each nest has 100 to 120 eggs, so this means several thousand never become hatchlings.

The problem was identified by local volunteers who realised that while foxes, which previously preyed upon the eggs, had successfully been killed off with poisoned bait, goannas had taken their place in recent years.

A coalition of academics, conservation volunteers, Aboriginal rangers and the World Wildlife Fund have been given funding by state and federal governments for a two-year project to tackle the problem.

However, initial hopes that chilli powder and red flags would work have been dashed, says the University of Queensland, which is leading the project.

“Hot chilli powder has been used in north and south America in the past to deter predators such as civets, so we had high hopes,” Dr David Booth, from the university’s school of biological sciences , told Guardian Australia.

“We scraped some sand off the nests and sprinkled hot chilli powder on it and covered it up again. But it didn’t work. Reptiles don’t have the same taste buds as mammals, so they weren’t bothered by it.

“We also put red flags up half a metre from each of the nests in the hope the visuals would scare the goannas off, but that didn’t work either.”

Facebook Twitter Pinterest A loggerhead turtle. Photograph: Christine Hof / WWF-Aus

The research has found that it is the yellow-spotted goannas, rather than lace monitors, that are the main culprits. GPS tracking and camera traps show the goannas digging open the nests and eating the eggs.

Further analysis of the goannas’ movements will identify whether it is just a few that prey upon the eggs, or all of the local population.

“It may be just a few individuals, so removing them may help,” Booth said. “If it’s all of them, that’s probably not a solution because goannas are native-protected animals. If that’s the case, we’ll have to focus on protecting each of the nests with barriers, which is a labour-intensive process each night and morning.”

Researchers have found that erecting a mesh around each nest keeps the goannas at bay, although this is a time-consuming process requiring volunteers to visit the beach every night and morning.

Booth said he hopes to find an easier solution to help safeguard loggerhead turtles, which are listed nationally as an endangered species. The turtles suffer from goanna predation on other beaches on a smaller scale, as well as death at the jaws of feral pigs and wild dogs.

“It would be great to get a goanna-centric solution,” Booth said. “Because they are endangered, we want to make sure as many hatchlings reach the sea as possible. Every little bit helps because of the long time it takes for hatchlings to become breeding adults – about 30 years or so. It’s important to look after this now, or we’ll see adult numbers plummet in the future.”

Bev McLachlan, a long-term volunteer at the beach, said: “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.”