A keeper at Wellington Zoo was sacked after she left a small female bird in an enclosure with a killer Australian crane named Bruce.
The peahen was promptly attacked and was so badly hurt it had to be put down.
The crane, named Bruce the Brolga, was known to have a violent temper. It was aggressive toward humans, had previously attacked a wallaby, and was the prime suspect in the killing of other birds, including another brolga crane.
Kelly Green, a keeper at the zoo for four years, was suspended from her job and was later dismissed. She appealed against the dismissal through the Employment Relations Authority.
Its report said Ms Green told a supervisor she had expected the peahen – the female version of a peacock – to fly out the top of the cage in the July 2010 incident.
"She said that she had noticed it had looked a bit slow and she suspected it had been sick in the previous two days and that was why it was perhaps unable to get away from the brolga."
The first Ms Green heard of her suspension was when she got a letter in August. It said she had acted with "gross negligence" and failed to ensure the safety of animals in her care.
Ms Green denied any negligence. The incident could have happened to any other staff member, she said.
At a disciplinary meeting, she said she caught a glimpse of "something" in the cage but did not immediately realise it was the peahen.
Ms Green said she loved her job, but it could be "stressful and exhausting".
In September she was told she would be sacked.
"No animal should have been confined with the brolga which is a known aggressive animal ... In this case, the brolga caused the death of the peahen due to your actions," a letter from the zoo said.
Brolgas are found in tropical Australia. They are known for their elaborate mating dances and sometimes violent temper.
Authority member Greg Wood said although there was no suggestion Ms Green's actions were deliberate, she had failed to ensure animal safety.
"Her wrongful assumption that the peahen would simply fly out of the enclosure was a fundamental failure that went to the core of her obligations as a zookeeper." However, Mr Wood found Ms Green's suspension was unfair. The zoo's letter was "effectively a fait accompli, rather than consultation", he said.
"The decision to suspend had already been made, and only granted her an opportunity to object, rather than be consulted beforehand, as the law requires."
The authority found Ms Green was justifiably dismissed, but unjustifiably suspended.
Wellington Zoo was ordered to pay $1000 compensation to Ms Green.
A Wellington Zoo spokeswoman said procedures for dealing with Bruce were in place before the incident. These had continued.
He was locked away at night for the protection of other animals, she said.