A little spotted kiwi has been busted on video killing robin chicks and destroying their nest.

Our beloved native kiwi has been exposed as a ruthless, cold-blooded chick killer.

A Victoria University researcher was shocked to see a robin's nest at Zealandia containing two chicks destroyed by an adult kiwi. The act was caught on a camera monitoring the nest.

The kiwi's attack lasted two nights, postdoctoral research fellow Rachael Shaw said. On its first visit - while the robin mother was away - the kiwi kicks away at part of the nest, effectively signing the chicks' death sentences.

FAIRFAX NZ A Wellington little spotted kiwi was exposed by a hidden night camera as the bird attacking a robin's nest twice.

"The kiwi uses its bill to probe at the nestlings, and you do see them wriggle in response. Then they fall out of the nest because [the male or female kiwi] has damaged it.

"It's unclear if when the chicks were on the ground if he had a look at them further. Because they do have little puncture wounds ... It could have been made by the claws on its feet but I wondered if it might have been made by the bill, but it's unclear."

The returning robin mother tried to feed and incubate at least one chick still alive outside the nest, but a tumble down the slope likely killed it alongside its nest mate, Shaw said.

The kiwi was seen on video returning the next night to tear the empty nest apart, she said. "I was shocked to find it was a kiwi. I was expecting a morepork or other bird."

Shaw first discovered the dead chicks when she went to band them, seeing the nest in pieces and the bodies not far away.

"If [the kiwi] hasn't had much experience of nestlings, he might have just been trying to figure out what they were."

It was then she turned to the video footage of the fixed camera pointed at the nest to find the identity of the bandit.

Shaw said it was unlikely anyone would ever know what motivated the kiwi to go on the attack, but noted the birds were notoriously territorial. The double visit makes Shaw suspect the nest may have been lined with kiwi feathers.

"Robins do like to use these as nest lining," she said.

"It may have reacted to the smell of that nest, as if it were an intruder on its territory.

"Because he did come back that second night it makes me think there was really something about that nest in particular that was drawing its attention."

The attack may not have been this kiwi's first. Several robins' ground nests were destroyed last year at Zealandia, which was one reason the cameras were set up.

Such a never-before-seen act by a kiwi could change the way both biologists and the general public thought about our national icon, she said. "If it turns out this behaviour is way more widespread and that kiwi will go after ground-nesting birds then that becomes interesting in its own right.

"Our birds are probably a bit tougher than we give them credit for, though unfortunately they don't stand up well to introduced pests."

Shaw estimated 400 robins pairs had bred in Zealandia this season. The loss of their chicks had been a fatal blow to the mating bond between this mother and father robin though, Shaw said. "The male now has a new female ... So it did lead to divorce sadly."