In a tragic case of mistaken identity, four critically endangered takahē birds have been accidentally killed in New Zealand after hunters misidentified the animals as a more common species.

The mixup occurred at a sanctuary on Motutapu Island, where volunteers from the Deerstalkers Association, a national body representing hunters, were participating in a regulated cull of up to 600 pukeko or Australasian swamphens – an abundant New Zealand bird that's considered a threat to other species due to its aggressive nature.

Takahe 2015-08-20 (1)
Although the colouring of the takahe is similar to the pukeko, they are at least twice as plump. Image: Ashleigh Thompson 

The country's Department of Conservation says the hunters were briefed on the distinct differences between the two birds, but according to an official, the pukeko has "very similar colouring" to the flightless takahē, so the volunteers could have mixed up the two species. The takahē is, however, at least twice as heavy as the more common Australasian swamphen.

News of the killings has angered local Maori groups, who agreed to have the rare birds relocated to Motutapu from their native South Island for conservation purposes. "There are even calls for the return home of those birds,” said a member of New Zealand’s parliament. “There is a lot of goodwill that goes with these gifts to improve the biodiversity and to see that they've been needlessly bowled over by some deer hunters is just really disappointing.”

Once abundant across New Zealand’s North and South Islands, the takahē was thought to be extinct for around 50 years until it was rediscovered in 1948. Special protected areas were set up to keep these rare birds safe from introduced predators and other threats. But despite long-running conservation efforts, it's thought there are still only about 300 takahē left in the country.

The head of the Deerstalkers Association has apologised to the Department of Conservation and to the country at large for the birds' deaths.

Pukeko 2015-08-20
The more abundant, slimmer pukeko or Australasian swamphen. Image: Sid Mosdell