Ironically the Kea were killed by the organisation that is supposed to protect them. Photo: Christian Mehlführer (Wikimedia commons)

The seven birds came from a group of 17 in the Fox Glacier region and had been fitted with radio transmitters to see how they reacted to the use of the poison, known as 1080.

Kea are endemic to New Zealand’s South Island and there are an estimated 1,000-5,000.  They are intelligent and inquisitive, and were once persecuted for their reputation as attackers of sheep. The main threat to Kea now comes from introduced mammals and they are classified as Vulnerable birds, having protection under New Zealand law.

The poison, also called sodium fluoroacetate, occurs naturally in some plants as a deterrent to herbivores. It is widely used in New Zealand to control mammalian pests, especially possums, stoats and rats as there are no native land mammals, apart from bats.  

A report on the use of 1080 has called on the Department of Conservation to review its use of the compound, especially in areas where Kea live. The poison is usually dropped from the air as pellets. MPs have called for an immediate ban on its use.