Doc Wakatipu operations manager Geoff Owen said 1080 control operations were designed to minimise by-kill of native wildlife, and its research showed few native birds were poisoned.
The Otago Daily Times approached Doc for comment after a reader photographed a dead yellow-crowned parakeet, or kakariki, near the Dart River on October 31. Queenstown man Eric Nauta found the bird on the ground a few metres from a 1080-laced pellet.
The bird was inside the drop zone of an aerial 1080 operation in the Dart, Routeburn and Caples valleys that took place on October 21.
Photos and video footage of dead wildlife and 1080 pellets have been widely shared on social media since the recent 1080 operations in the Wakatipu and Fiordland. Mr Owen said it was possible the kakariki had died from 1080 poisoning, but that could only be confirmed with an autopsy.
"If people are concerned about potential bird deaths from 1080 poisoning, they need to bring the carcass to Doc to get assessed."
In the case of kakariki, the benefits of 1080 "far outweighs the small number of birds that may be poisoned".
"With substantially reduced nest predation there will be many more young birds entering the population, as well as fewer adult birds killed on the nest."
Doc had studied the effects of aerial 1080 operations on the survival and breeding success of species including kiwi, kea, rock wrens, kaka, whio, moreporks, riflemen, robins, weka and bats, he said.
Weka, robins and kea had been poisoned by 1080 using current pest control methods. Uncertainty remained about the effect on rock wrens, and more research was being done on that species, he said.
"However, for all these species any losses have been more than offset by the big gains from pest control.
"Without pest control these species would continue to decline."
Queenstown partnerships ranger Chris Hankin said the Dart Valley had been a key study site for mohua for at least a decade, and ongoing monitoring would give Doc good information about how mohua had responded to the latest operation.
Doc did not have the resources to monitor all bird species in the Wakatipu to the same degree, but other species were being monitored closely elsewhere in the country.
Mr Nauta said Doc’s response to his photograph did not alleviate his concerns, as he had heard many first-hand accounts of people finding dead wildlife after aerial 1080 operations.
He also worried that concentrations of the poison would accumulate in fish and other water life if aerial operations continued year after year.
He had stopped fishing in rivers downstream of 1080 drop zones as a result.
"The technology we have isn’t sensitive enough yet to tell us if there are traces of 1080.
"I’m concerned that it’s potentially doing a lot of long-term damage."
He accepted the case for using 1080 in a highly targeted way, but was disturbed by Doc’s "gung-ho" approach, he said.
1080 and kakariki
• Doc has studied the effects of 1080 predator control and traps on yellow-crowned kakariki survival rates and nesting success on 11 occasions between 1990 and 2009.
• In one study, 58 kakariki were monitored during three separate 1080 operations in the Dart Valley, Canterbury’s Hurunui South Branch and the West Coast’s Lake Daniels between 2006 and 2009. One bird died from 1080 poisoning, giving a mortality rate of 1.7%.
• The research showed that when no pest control was carried out when stoat and rat levels were high, an average 48% of nests had at least one chick fledge.
• When pest control using either traps or poisoned bait stations was carried out, nesting success increased to 57%.
• When traps and aerially applied 1080 were used, 89% of nests were successful.
