KEY POINTS:
Shy, elusive, retiring and quiet. Couldn't possibly be talking about Australians. Especially that most iconic of Australians, the kookaburra.
But Unitec researcher and senior lecturer John Perrott is finding the famously loud birds near-impossible to locate on this side of the Tasman.
In an attempt to understand why kookaburras, introduced to New Zealand at Kawau Island by Governor George Grey in the 1860s, have not thrived like other new avian arrivals, Dr Perrott first needs to find the surviving New Zealand populations.
"There's been quite a few sightings of them, but they're not the easiest birds to find," he said. "The nests themselves are very hard to find and access because they are so high up in the trees. So it's proving an interesting exercise."
He has found just one nest so far, and is following reports of a further six in an area stretching from Kumeu to Matakana, where the majority of the 300- to 500-strong population is believed to exist. But despite ample nesting sites and a lack of predators in those spots, the birds are barely surviving, he said.
"Our theory is that in New Zealand the family unit is very small because they're only managing to feed one chick instead of two or three. Some anecdotal studies show most nesting attempts fail because of starvation.
"In Australia, the kookaburras have a longer breeding season and feed off reptiles and snakes. But here they have a much shorter time to get their weight up."
Analysing matter taken from a kookaburra nest, Dr Perrott and his team had learned the kookaburra fed off other birds, mice, freshwater crayfish, native beetles and other invertebrates.
It was also likely New Zealand's undergrowth, which was far denser than the open forest of Australia, made the birds' natural "sit and wait" hunting method less effective, Dr Perrott said.
But kookaburra did not seem to be feeding on endangered native species, he said.
"There's no evidence to suggest that is happening. But there's always a danger and we're going to investigate whether these concerns are valid.
"There's no sense in losing rare endemic species to a widespread exotic one that is not endangered, though we have no evidence that this is the case yet."
Dr Perrott's research will begin in earnest in spring and is expected to continue for several years.
