Staff at Dannevirke's Gallery of History are reeling after the theft of its prized female huia.
The bird was displayed in a glass-fronted case along with a male huia.
The glass was prised open and the huia removed either on Wednesday or yesterday.
The theft was discovered yesterday afternoon just as museum president Nancy Wadsworth was about to show the huia to visitors.
She said the theft was a disaster.
CCTV footage is being searched in an attempt to identify the thieves.
The Gallery of History was closed after the theft as committee members and volunteers were devastated.
It's not the first time the huia have been targeted by thieves. In 2012 the two tail feathers were stolen from the male.
"It's pretty clear the thieves knew exactly what they were after this time as they didn't touch the male. They must have known its tail feathers weren't genuine," Wadsworth said.
Gallery volunteer Murray Holden said he had been told that a pair of huia had recently sold in London for $30,000.
"This is very sad, not only for the gallery but for the people of Dannevirke, it's part of the district's heritage," Holden said.
There were concerns the stolen female could be damaged.
"When we had the feathers replaced on the male we asked the repairer if he could fix the feathers on the female as they were very ruffled, but he said she was too fragile to touch."
The birds were donated by the Galloway family more than 30 years ago and had been the gallery's biggest drawcard.
The birds were shot in Pohangina Valley in 1889 and mounted as a wedding gift for a local couple. They were reported to be the last huia in the valley.
The last confirmed sighting of the endemic bird was in 1907, although some say there were credible sightings as late as the early 1960s.
The species was highly prized for its unique white-tipped black tail feathers. In 2010 a tail feather sold for $8400 at Webb's Auction House in Auckland, which was believed to be a record for a bird feather at that time.
The huia is one of New Zealand's best-known extinct birds because of its bill shape. The female has a long curved bill and the male has a shorter, straighter bill.
It was regarded by Māori as tapu and the wearing of its skin or feathers was reserved for people of high status.
The Gallery of History is offering a reward for the safe return of its huia.