Possum numbers in the West Coast's Perth River Valley area have potentially reduced from roughly 10,000 to just 30 after a new technique was used in a 1080 operation.
Zero Invasive Predators (ZIP) is in charge of the operation in the Perth River Valley area in South Westland. The operation is halfway through and has involved the deployment of 4 kilograms of 1080 per hectare so far.
Zero Invasive Predators (ZIP) is in charge of the operation in the Perth River Valley area in South Westland. The operation is halfway through and has involved the deployment of 4 kilograms of 1080 per hectare so far.
In statement, ZIP confirmed two kea had also died as a result of the operation. ZIP said the deaths were anticipated though and would not have a lasting impact on the area's kea population.
"Six of the radio-tagged adult female kea in the area survived the operation," the statement said.
"This is an important outcome for the population, because the ground-nesting habits and extended nesting cycle of adult female kea make them particularly vulnerable to predation, and therefore most likely to benefit from the removal of predators."
Initial estimates using cameras suggested there were only about 30 possums left, compared to roughly 10,000 before the drop.
The number of rats in the area were also thought to have reduced from about 5000 to 15, and the number of stoats dropped from about 40 to just three.
ZIP chief executive Al Bramley said in a normal 1080 operation, a non-toxic drop was spread first to attract possums to the area. It was then followed by a toxic drop, which aimed to kill as many possums as possible.
The technique involved with the Perth River Valley operation was slightly different though, with the non-toxic drop done twice "to make sure all animals are covered".
"Then we put the first toxic drop down and this is where we are now ... around 10,000 possums down to roughly 30."
Five people were now working in the Perth Valley to confirm how many possums were left.
"The most effective method of tracking the numbers is through cameras lured with egg mayonnaise, this disperses intermittently to attract possums and get them into a habit of coming back to these areas," Bramley said.
"The goal here is all about the complete removal of possums, so that we can do it once and never use 1080 again."
ZIP will now spend two years tracking population levels to determine how successful the operation was.
"Six of the radio-tagged adult female kea in the area survived the operation," the statement said.
"This is an important outcome for the population, because the ground-nesting habits and extended nesting cycle of adult female kea make them particularly vulnerable to predation, and therefore most likely to benefit from the removal of predators."
Initial estimates using cameras suggested there were only about 30 possums left, compared to roughly 10,000 before the drop.
The number of rats in the area were also thought to have reduced from about 5000 to 15, and the number of stoats dropped from about 40 to just three.
ZIP chief executive Al Bramley said in a normal 1080 operation, a non-toxic drop was spread first to attract possums to the area. It was then followed by a toxic drop, which aimed to kill as many possums as possible.
The technique involved with the Perth River Valley operation was slightly different though, with the non-toxic drop done twice "to make sure all animals are covered".
"Then we put the first toxic drop down and this is where we are now ... around 10,000 possums down to roughly 30."
Five people were now working in the Perth Valley to confirm how many possums were left.
"The most effective method of tracking the numbers is through cameras lured with egg mayonnaise, this disperses intermittently to attract possums and get them into a habit of coming back to these areas," Bramley said.
"The goal here is all about the complete removal of possums, so that we can do it once and never use 1080 again."
ZIP will now spend two years tracking population levels to determine how successful the operation was.
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