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ABC Wide Bay
By Eliza Goetze
PHOTO: The much-maligned pest could have a new us — fending off goannas from turtle nests. (Supplied: Department of Parks and Wildlife)
Cane toads, one of Queensland's most hated pests, could become unlikely heroes in the quest to protect endangered turtles.
The much-maligned cane toad has been trialled as a deterrent to keep goannas away from vulnerable nests at the state's second-most significant breeding beach for loggerhead turtles.
And it all came about by accident.
Goannas cause chaos at turtle nesting sites
At Wreck Rock, halfway between Bundaberg and Agnes Water, loggerhead turtles have a tough start to life before they even hatch.
Goannas and foxes stalk the nests, with a recent study finding goannas had overtaken foxes as the number one predator of loggerheads in the area.
Using camera traps, University of Queensland researcher David Booth found the lizards had increased their raids on nests in the dunes at Wreck Rock, disturbing up to 400 nests a year.
Turtle Care volunteers Bev and Nev McLachlan, who have camped at Wreck Rock every summer for the past 40 years, have experienced the frustration first-hand.
"Once they get a taste for the turtles — the eggs in particular — they dig the nests and there's not much we can do about the goannas, because they're a protected species," Mr McLachlan said.
"Once they find one they want, they'll dig the nest out and destroy it. They eat a lot of the eggs, but the rest they just spread over the sand.
"We're losing five or six nests per night at the moment and a lot of the time, there's only five or six nests being laid each night by turtles."
PHOTO: Nev McLachlan says goannas have become more of a threat to turtles over the past 10 years. (Supplied: University of Queensland)
A turn-off for goannas
The potential solution to the goanna problem was pioneered just north of Wreck Rock.
Agnes Water locals and long-time turtle taggers Gary Simpson and Kelly Elsmore had been inspired by an experiment with quolls in the Northern Territory and put it to the test at Red Rock beach.
"[They] put some toads on top of the turtle nests and found the goannas were avoiding them, so we did an experiment with it ourselves," Mr McLachlan said.
"We found some cane toads that were squashed on the track by four-wheel-drives and put them on the nests around areas where goannas were digging up lots, and we found they were avoiding those nests."
Dr Booth said in areas newly invaded by cane toads, goanna populations crashed when the lizards mistook the poisonous toads for frogs, a popular food source.
"But in areas like Wreck Rock, where cane toads have been for 50 or 60 years, it appears the goannas have learned not to eat them … and they are repelled by them," he said.
Cooking up a solution
After studying the way goannas attack turtle nests, Dr Booth believes the cane toad deterrent could be one of the next steps in his research.
"It could be a long-term project to have a look at what the active avoidance mechanism is," he said.
"It could be some kind of [chemical] that's produced by the skin secretions that the goannas smell and avoid.
"If you were to find that's what could happen, you could manufacture that [chemical] artificially, put it in a solution and spray it over a nest every couple of days, and presumably the goannas would stay away."
He said to get that research underway, it would take some time, effort and money.
PHOTO: Bev and Nev McLachlan say a ready-made solution using the cane toad secretions could make their job monitoring turtles much easier. (ABC Wide Bay: Eliza Goetze)
For the McLachlans and the turtles they care for, a manufactured solution would be a lifesaver.
"We haven't yet got enough evidence, enough time or enough cane toads to really look at the problem seriously," Mr McLachlan said.
"Until we can find a humane way of killing lots of cane toads so we can do some experiments on them, at the moment we're just using road kill."
And tossing dead cane toads onto every turtle nest would be too labour intensive across the 23km stretch of beach the couple patrols each night.
The McLachlans are hoping someone will take on the passion project to take the breakthrough from experiment to reality.
"If we had some sort of deterrent that was maybe in a spray bottle or a pellet that we could throw on or spray onto a nest when it's laid, that would certainly make our job a whole lot better," Mr McLachlan said.
It could allow a few more turtles a fighting chance at life outside the nest.
By Eliza Goetze
PHOTO: The much-maligned pest could have a new us — fending off goannas from turtle nests. (Supplied: Department of Parks and Wildlife)
Cane toads, one of Queensland's most hated pests, could become unlikely heroes in the quest to protect endangered turtles.
The much-maligned cane toad has been trialled as a deterrent to keep goannas away from vulnerable nests at the state's second-most significant breeding beach for loggerhead turtles.
And it all came about by accident.
Goannas cause chaos at turtle nesting sites
At Wreck Rock, halfway between Bundaberg and Agnes Water, loggerhead turtles have a tough start to life before they even hatch.
Goannas and foxes stalk the nests, with a recent study finding goannas had overtaken foxes as the number one predator of loggerheads in the area.
Using camera traps, University of Queensland researcher David Booth found the lizards had increased their raids on nests in the dunes at Wreck Rock, disturbing up to 400 nests a year.
Turtle Care volunteers Bev and Nev McLachlan, who have camped at Wreck Rock every summer for the past 40 years, have experienced the frustration first-hand.
"Once they get a taste for the turtles — the eggs in particular — they dig the nests and there's not much we can do about the goannas, because they're a protected species," Mr McLachlan said.
"Once they find one they want, they'll dig the nest out and destroy it. They eat a lot of the eggs, but the rest they just spread over the sand.
"We're losing five or six nests per night at the moment and a lot of the time, there's only five or six nests being laid each night by turtles."
PHOTO: Nev McLachlan says goannas have become more of a threat to turtles over the past 10 years. (Supplied: University of Queensland)
A turn-off for goannas
The potential solution to the goanna problem was pioneered just north of Wreck Rock.
Agnes Water locals and long-time turtle taggers Gary Simpson and Kelly Elsmore had been inspired by an experiment with quolls in the Northern Territory and put it to the test at Red Rock beach.
"[They] put some toads on top of the turtle nests and found the goannas were avoiding them, so we did an experiment with it ourselves," Mr McLachlan said.
"We found some cane toads that were squashed on the track by four-wheel-drives and put them on the nests around areas where goannas were digging up lots, and we found they were avoiding those nests."
Dr Booth said in areas newly invaded by cane toads, goanna populations crashed when the lizards mistook the poisonous toads for frogs, a popular food source.
"But in areas like Wreck Rock, where cane toads have been for 50 or 60 years, it appears the goannas have learned not to eat them … and they are repelled by them," he said.
Cooking up a solution
After studying the way goannas attack turtle nests, Dr Booth believes the cane toad deterrent could be one of the next steps in his research.
"It could be a long-term project to have a look at what the active avoidance mechanism is," he said.
"It could be some kind of [chemical] that's produced by the skin secretions that the goannas smell and avoid.
"If you were to find that's what could happen, you could manufacture that [chemical] artificially, put it in a solution and spray it over a nest every couple of days, and presumably the goannas would stay away."
He said to get that research underway, it would take some time, effort and money.
PHOTO: Bev and Nev McLachlan say a ready-made solution using the cane toad secretions could make their job monitoring turtles much easier. (ABC Wide Bay: Eliza Goetze)
For the McLachlans and the turtles they care for, a manufactured solution would be a lifesaver.
"We haven't yet got enough evidence, enough time or enough cane toads to really look at the problem seriously," Mr McLachlan said.
"Until we can find a humane way of killing lots of cane toads so we can do some experiments on them, at the moment we're just using road kill."
And tossing dead cane toads onto every turtle nest would be too labour intensive across the 23km stretch of beach the couple patrols each night.
The McLachlans are hoping someone will take on the passion project to take the breakthrough from experiment to reality.
"If we had some sort of deterrent that was maybe in a spray bottle or a pellet that we could throw on or spray onto a nest when it's laid, that would certainly make our job a whole lot better," Mr McLachlan said.
It could allow a few more turtles a fighting chance at life outside the nest.
