Invaders march on
By ED SOUTHORN
THE biggest cane toad survey ever conducted in the Northern Rivers has found the toxic pests are spreading into previously toad-free zones in at least one Tweed region national park.
NSW National Parks and Wildlife Service pest management officer Lisa Well-man yesterday said cane toads were spreading into the Mebbin National Park, south-east of Tyalgum, adjacent to the Border Ranges National Park.
Mrs Wellman said toads had crept into the Border Ranges park only two years ago, and they had also become more prevalent at Coraki, Woodenbong and Old Bonalbo near the Tweed in the past 12 months.
In the Wollumbin National Park, at the base of Mt Warning where toads had already been found, and in the Mebbin park, the NPWS is trialling new toad "supertraps".
The supertraps, devised by NPWS staff and modelled on similar traps used in the Northern Territory, can hold up to 60 toads each, collected over a two-to-three-week period.
Each supertrap is more than a metre long, almost a metre wide and 600cm high.
The traps are being monitored by Southern Cross University student Adam Greenhalgh to see if they also trap native animals, but so far they have only caught toads.
"Depending on funding, we may roll out a lot more traps across the Northern Rivers later this year," Mrs Wellman said.
She said cane toads were particularly dangerous to the Northern Rivers quoll population.
As well, the NPWS toad survey is trialling a new toad euthanasia product, Aqui-S, used in the aquaculture industry to tranquilise fish.
"It's based on clove oil and we use it to overdose the toads, they just go to sleep," Mrs Wellman said.
"Cane toads are known to migrate along roads, so our survey method was designed to take advantage of the toad's laziness.
"By dividing the survey area into one- kilometre intervals along park roads, a wide range of parks were able to be surveyed quite quickly by watching and listening for the toads."
The toads were found in the Border Ranges, Mebbin, Mooball, Billinudgel, Nightcap, Goonengerry and Mount Jerusalem national parks and Yarringully, Bungabbee and Muckleewee Mountain nature reserves.