People feeding kea in South Island high country car parks have made the intelligent and curious alpine parrots more likely to nibble things they shouldn't - including a pest control poison.
That poison is being spread across more than a million hectares of conservation land, in a bid to stop a predicted "rodent plague" from devouring native bird eggs and chicks, and denting the already-endangered kea species.
Mice, rats and stoat numbers are expected to explode following a "mega mast", or heavy seeding, of beech trees, which will soon litter forests with a buffet of rodent food not seen in 40 years.
Department of Conservation scientist Dr Graeme Elliott said the 1080 drops, this year and next, could save the kea population, but could also cause a few kea deaths as those living near car parks and cafes have been known to fatally nibble the bait.
"The trick is, don't feed the buggers ... we're teaching them to eat things they shouldn't be," Elliott said at the Marlborough Biodiversity Forum on Sunday.
Mountain-dwelling kea were less likely to eat the bait, but those living near camp grounds, rubbish tips, tourists and towns were at risk because of their interactions with people, he said.
"They are far more vulnerable than kea in remote country ... they will come right up to you and say hello, they know about people and they regularly scavenge in car parks, and eat whatever you offer them.
"But kea in the backcountry haven't learnt to nibble at things ... they already know what's good to eat."
Kea nested on the ground, where eggs and chicks were vulnerable to predators, so a 1080 operation that wiped out rodents in the area could lift their survival rates from 40 per cent to 60 per cent, Elliott said.
"They're headed for extinction if we do nothing. So 1080 works, but a few kea do get bowled by it, it's a real worry."
The ongoing $30 million national 1080 operation was intended to dent the "plague of rodents" following the beech seed mega mast that arrived with spring this year.
The native beech trees were populous in the Pelorus and Nelson Lakes areas, and usually flowered every three or four years. The most recent mast was in 2016, but this summer's mast was tipped to be the worst in 40 years, according to temperature data.
Flowering would turn the green trees to red, with clouds of pollen visibly wafting over hillsides, Elliott said.
A heavy seeding event could spread 50 million seeds per hectare, and a forest's bird, insect and spider populations would flourish. "And then they breed, and there's squillions of them."
In fact after two consecutive mega masts in 1999 and 2000, the rodent population on Mt Stokes in the outer Marlborough Sounds "slaughtered" the mohua, causing the native bird to go extinct in the area, Elliott said.
"Every time you get a stoat plague, the mohua numbers crash. They go up again later, but you never get them back to where they were," Elliott said.
"They are particularly vulnerable because they nest in holes ... if a rat comes along the female might get away but for any chicks, it's all over."
There were several other vulnerable native species, including the brown kiwi, the rifleman and the South Island robin.
The aerial poison was by far the most effective way to cull rodents over large areas, Elliott said. "Trapping, it's bloody hard to do anything except small areas."
Studies of nesting birds showed survival rates of chicks at nearly 100 per cent following a 1080 drop, much higher than normal rates for species such as kaka, which only had about 20 per cent survival rate without 1080 drops.
However a study of weka at Tennyson Inlet revealed 90 weka monitored over four 1080 operations all ate the bait, and none of them died, Elliott said.
"Either they're just not vulnerable to the poison, or they barf it up before they die. It's a much more effective mammal killer than a bird killer. So they got away with it."
Few stoats were prepared to take on a weka anyway, Elliott said.
"We've got videos of stoats and even cats actually backing away from them."
Mice, rats and stoat numbers are expected to explode following a "mega mast", or heavy seeding, of beech trees, which will soon litter forests with a buffet of rodent food not seen in 40 years.
Department of Conservation scientist Dr Graeme Elliott said the 1080 drops, this year and next, could save the kea population, but could also cause a few kea deaths as those living near car parks and cafes have been known to fatally nibble the bait.
"The trick is, don't feed the buggers ... we're teaching them to eat things they shouldn't be," Elliott said at the Marlborough Biodiversity Forum on Sunday.
Mountain-dwelling kea were less likely to eat the bait, but those living near camp grounds, rubbish tips, tourists and towns were at risk because of their interactions with people, he said.
"They are far more vulnerable than kea in remote country ... they will come right up to you and say hello, they know about people and they regularly scavenge in car parks, and eat whatever you offer them.
"But kea in the backcountry haven't learnt to nibble at things ... they already know what's good to eat."
Kea nested on the ground, where eggs and chicks were vulnerable to predators, so a 1080 operation that wiped out rodents in the area could lift their survival rates from 40 per cent to 60 per cent, Elliott said.
"They're headed for extinction if we do nothing. So 1080 works, but a few kea do get bowled by it, it's a real worry."
The ongoing $30 million national 1080 operation was intended to dent the "plague of rodents" following the beech seed mega mast that arrived with spring this year.
The native beech trees were populous in the Pelorus and Nelson Lakes areas, and usually flowered every three or four years. The most recent mast was in 2016, but this summer's mast was tipped to be the worst in 40 years, according to temperature data.
Flowering would turn the green trees to red, with clouds of pollen visibly wafting over hillsides, Elliott said.
A heavy seeding event could spread 50 million seeds per hectare, and a forest's bird, insect and spider populations would flourish. "And then they breed, and there's squillions of them."
In fact after two consecutive mega masts in 1999 and 2000, the rodent population on Mt Stokes in the outer Marlborough Sounds "slaughtered" the mohua, causing the native bird to go extinct in the area, Elliott said.
"Every time you get a stoat plague, the mohua numbers crash. They go up again later, but you never get them back to where they were," Elliott said.
"They are particularly vulnerable because they nest in holes ... if a rat comes along the female might get away but for any chicks, it's all over."
There were several other vulnerable native species, including the brown kiwi, the rifleman and the South Island robin.
The aerial poison was by far the most effective way to cull rodents over large areas, Elliott said. "Trapping, it's bloody hard to do anything except small areas."
Studies of nesting birds showed survival rates of chicks at nearly 100 per cent following a 1080 drop, much higher than normal rates for species such as kaka, which only had about 20 per cent survival rate without 1080 drops.
However a study of weka at Tennyson Inlet revealed 90 weka monitored over four 1080 operations all ate the bait, and none of them died, Elliott said.
"Either they're just not vulnerable to the poison, or they barf it up before they die. It's a much more effective mammal killer than a bird killer. So they got away with it."
Few stoats were prepared to take on a weka anyway, Elliott said.
"We've got videos of stoats and even cats actually backing away from them."
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