What exactly is, and is not, considered a native bird? And how is this decided?
It seems like a simple question but it could be harder to define than we think.
Takahē (right) are roughly twice the size of pūkeko, and flightless. Photo: 123RF / Wikimedia Commons / CC-BY-3.0
Listen to Mike Dickison's interview with Jesse Mulligan
Whanganui Regional Museum curator of natural history Mike Dickison is holding a talk on the matter this Thursday and told Jesse Mulligan the distinction between the two isn’t as neat and tidy as we may like to think.
He says some birds that are deemed to be native, for example pukeko and harrier hawks, have no fossil trace before Polynesian settler arrived in NZ.
“It’s likely that pukeko flew here from Australia after Polynesian settlement and the clearance of a lot of our lowland forests, making all this nice open pukeko habitat. Same with Harrier hawks.
“They’re sort of ‘self-introduced’, yet most people consider them fully native.”
He says there’s debate over whether the silvereye arrived in NZ on its own, or had help.
“If they got here on their own steam they’re supposedly a native, if they hitched a ride on a ship they’re supposedly an introduced bird, but there’s actually no difference really in practice.
“It’s a ridiculously arbitrary point.”
The timings for some other species, such as black swans, are slightly more complex.
“Black swans were brought here back in about the 1860s from Australia, and so they’re introduced, but we’ve also go fossils of swans living in pre-European, pre-Māori times.
“They must’ve colonised New Zealand on their own at some point and then have been wiped out by the first human settlers here only to be reintroduced in the 19th century.”
Dr Dickison says the biggest change to have happened to New Zealand was around 750 years ago.
“When people arrived, modified the landscape, opened it up to a whole bunch of new birds that had been previously arriving in drips and drabs from Australian but were never able to get a toehold.
“To me the big difference is the birds that are here because of humans, and then all the stuff that was here before people.”
But he says many introduced birds aren’t driving out native species, and are living happily side by side with them.
“It’s not like they’re introduced rats or stoats or something.”
Dr Dickison wants to see New Zealand’s ecosystem managed more like a garden.
“What sort of ecosystem is it that we’re trying to recreate?”
“We have to accept that the conservationist state in New Zealand isn’t this pristine natural state that if we just get rid of all these so-called introduced things it’ll all be dandy.”
Dr Dickison’s lecture on Thursday will be held at the Davis Theatre in Whanganui.