Kiwi may give Polly run for its cracker

DAVID HALLETT

NO BIRD BRAIN: Although they only have small heads kiwis are not bird brains, researchers have found

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Although they only have small heads kiwis are no bird brains, researchers have found.

A study at the University of Auckland has found the kiwi rules the roost in terms of brain size, having a relatively larger and more developed brain than its peers.

Dr Fabiana Kubke, from the university's Department of Anatomy, said the kiwi had a larger brain relative to its size compared with other birds that evolved at a similar time such as the moa, ostrich and emu.

"The forebrain -- which is the area where intelligence is thought to lie -- was especially developed," said Kubke.

Birds are split into two families known as paleaognaths and neognaths. Paleaognaths, including the kiwi, are descended from an ancient ancestor in the Cretaceous period and evolved earlier than neognaths which make up most modern birds.

Neognaths generally have larger brains than their older counterparts.

"The total brain of a kiwi is of a size which is pretty much that of an average modern bird," Kubke said.

"However, it has an above average brain size for a paleaognath."

She said the results were "confusing" since the kiwi did not behave like birds with similarly developed brains, such as the kea.

"It is easy when you look at the kea or parrots because they imitate language. With the kiwi its more difficult and we don't know whether the development is to do with information processing."

PhD student Jeremy Corfield, who is studying the kiwi for his thesis, said the results had been a shock. "The results were surprising. It is pretty much 82 per cent forebrain, which is really massive and similar to that of a parrot," he said.

Corfield analysed eight carcasses of three different species of kiwi using magnetic resonance imaging (MRI) to analyse their brain structure.

Permission to use the carcasses was given by the Department of Conservation (DOC) after consultation with local iwi in the areas the birds came from. Corfield said brain development could be linked to advanced communication.

"I am very interested in looking more into the auditory system and getting some idea of what they can hear and what they are processing," he said.

Brent Beven, biodiversity manager at Rakiura National Park on Stewart Island, said the kiwi had a very developed sense of smell and hearing.

"I wouldn't be surprised if the size of their brain is linked to that," he said. "They have a very strong social structure and they are able to keep a 3D map in their head of their territory and navigate their way around and pinpoint sounds."

- © Fairfax NZ News