Deadly kiwi whacks robins on her turf

New Zealand's national icon has a rather nasty mean streak.

Scientists have captured on camera a cold-hearted kiwi destroying a robin nest - and causing the death of chicks in it - and it all might have only been over a few borrowed feathers.

Over two consecutive nights at Wellington sanctuary Zealandia, the little spotted kiwi was shown pushing the robin nest down a slope, pecking the chicks, and returning the next night to tear the nest apart.

"That morning I went to band the nest of robin chicks, when I discovered the nest had been pulled out from its location and the chicks were dead," said Dr Rachael Shaw, a postdoctoral research fellow in Victoria's School of Biological Sciences.

"I noticed the chicks had peck injuries on their bodies."

But it was only when Dr Shaw, who is studying the robin population at Zealandia, checked camera footage that she found the culprit.

"I was shocked to find it was a kiwi. I was expecting a morepork or other bird to have destroyed the nest."

Although the kiwi didn't directly kill the chicks, they had "pretty severe injuries", she said.

"The video shows that the chicks were still alive after being pecked by the kiwi and then fell out of the nest, most likely to their deaths."

She couldn't say for certain what might have motivated the kiwi to destroy the nest, but speculated it may have been acting defensively.

"One possibility is that the robin may have lined the nest with kiwi feathers, because robin do like to use these as nest lining.

"Kiwi are highly territorial, so it may have reacted to the smell of that nest, as if it were an intruder on its territory.

"While it's sad for the robins it's exciting to be making new scientific discoveries like this, and potentially uncover a new behaviour that might change the way we look at our national icon."

There are only an estimated 2500 little spotted kiwi left in New Zealand - including about 70 at Zealandia at last count.