Seven kea died after being inadvertently caught in stoat traps in the Murchison Mountains, prompting the Department of Conservation to "kea proof" hundreds of traps.

Routine checks in the area above Lake Te Anau have revealed a new level of kea damage to traps in the southern part of the takahē management area, including kea breaking into boxes resulting in seven of the at-risk species being killed in stoat traps.

DOC senior ranger George Ledgard said the traps were housed in solid wooden boxes to deter kea but some birds gouged out the lid screws and prised the lids open to get to the egg and meat bait inside.

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The birds also dug up the trap footings and rolled traps downhill, sometimes over bluffs and into Lake Te Anau.

"Kea are naturally inquisitive and have meddled with traps in the Murchison Mountains before but this type of damage is new

"We've modified the traps previously but these incidents have required us to design and fit a new bracket to stop the trap boxes from being opened," Ledgard said.

During summer about 700 traps had been upgraded with longer screws and a specially designed bracket to keep the lids in place. A wider trap check throughout the management area completed in past weeks confirmed no other kea had been caught in traps.

"It appears that young kea in this particular area worked out how to prise open the traps with unfortunate consequences," Ledgard said.

"However, we're confident the upgraded boxes will now keep kea out of the traps."

With more groups doing pest control in areas where kea live, DOC and the Kea Conservation Trust are keen to hear from anyone using traps where kea damage has been an issue or where kea have been inadvertently caught or killed.

Kea are a mountain parrot found in alpine and forest areas throughout the South Island. The size of the population is unknown but is estimated at between 1000 and 5000 and its conservation status is 'at risk'. Kea nest on the ground and are particularly vulnerable to being preyed on by stoats and possums.

An observed increase of young kea within the takahē management area in recent years indicates kea are also benefiting from stoat protection.

The Murchison Mountain trap network protects New Zealand's only remnant wild population of takahē from stoats and consists of 3500 double trap boxes over the 50,000-hectare area.