DOC believe kea, such as this one on Milford Rd, that are exposed to human food may be more vulnerable to picking up 1080 cereal baits.

Environmentalists fear hundreds of birds may have been killed in a 1080 drop in Otago but Department of Conservation (DOC) staff say no such conclusion can be made.

On Monday DOC announced six of 12 monitored kea in the Matukituki Valley, near Wānaka, died following an aerial 1080 predator control operation.

DOC expects to get autopsy results this week that will determine the cause of the deaths.

PATRICK WOOD/SUPPLIED Kea studied at Auckland University have proven they're as smart as primates. (Video first published in March 2020)

According to DOC figures there have been 27 kea deaths attributable to 1080, prior to this incident.

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That includes seven kea out of 17 monitored birds that died at Fox Glacier in 2009, eight kea at Okarito on the West Coast in 2011, five in Arthur's Pass in 2013 and two of 14 kea being monitored in a 1080 operation in the Perth River area of the West Coast in 2019.

MAT GOODMAN Kea are considered endangered with an estimated population of between 3000 and 7000.

Ecologist Bill Wallace, founder of the Ban 1080 Party, said the reported deaths in the Matukituki Valley equated to half of the monitored kea in the area, which could mean hundreds of endangered kea died.

DOC threats director Amber Bill said it was not known how many kea lived in the area but the national kea population is thought to be between 3000 and 7000.

If the deaths of the six kea were attributed to 1080 then it could not be inferred that half the kea in the area would have died, she said.

The kea were monitored by the Kea Conservation Trust and the controls were not designed to test questions about risk to kea from 1080.

The kea were opportunistically caught, many near huts so were at greater risk as DOC research showed the risk of 1080 to kea increased when birds had learnt to scavenge for human food, she said.

"DOC's research on risk to kea from 1080 shows that the risk of poisoning to kea in remote areas is low and is easily offset by the benefits of predator control of increased nesting success and more young birds entering the population."

Wallace was also concerned DOC had done no research on the effects of sub-lethal 1080 doses on breeding habits of kea, either by not mating, laying infertile eggs or abandoning their nests.

"And what about the insects? What about wrens? What about all those other birds who are too small to carry a transmitter?"

Bill said DOC research showed well-timed aerial 1080 operations and traps enabled kea nesting success and chick production increased significantly.

"Only about 10 per cent of kea nests are successful without predator control following a mast year when rat and stoat numbers soar," Bill said.

"After predator control about 70 per cent of kea nests are successful and produce at least one chick."

The reaction of many birds to 1080 drops were monitored, including kiwi, robins, blue duck, rock wrens and mohua, she said.

After news of the Matukituki Valley deaths the NZ Outdoors Party announced it was seeking an immediate moratorium on the use of 1080.

Co-leader Alan Simmons said it was not the first time the organisation had written to DOC calling for a moratorium, but they had yet to receive a reply.

The organisation was considering getting funding to pursue a private prosecution against DOC as it considered the use of 1080 was a breach of the Wildlife Act.

* This article has been changed to correct the number of monitored kea during the Perth River operation.