Bird helpers biding time before trapping

Successful clutch and hatching at Albert Town in the second year of the Cardrona Karearea...
Successful clutch and hatching at Albert Town in the second year of the Cardrona Karearea Conservation Project. PHOTOS: SUPPLIED
Introduced mammalian predators are taking karearea, or New Zealand falcon, eggs and chicks from their nests in the Cardrona Valley but it is too soon to start trapping, a scientist says.

One of the banded adult karearea monitored in the karearea conservation project.
One of the banded adult karearea monitored in the karearea conservation project.
Parker Conservation ecologist Graham Parker is about to start surveying the population, health and breeding success of New Zealand’s only endemic falcon in the tussock grassland mountain environment for the third consecutive year.

Mr Parker is the principal scientist on the five-year Cardrona Karearea Conservation Project.

He said falcons in coastal plantation forests were doing incredibly well, but there was a lack of good scientific information on the species in the high country.

"We do not really know what is going on, so before we disrupt the unadulterated picture, which means trapping or poisoning the predators, we need to know what is happening on the nests first."

Karearea nest on the ground, and are prone to nest disturbance and abandoning their nests in the first two weeks of incubation.

Six breeding pairs were surveyed last year and each monitored nest had a photo trail camera and motion sensor camera attached.

Mr Parker said he had hoped to have a larger group of juvenile birds to monitor this year but many of the nests failed early on.

Some of the nests were preyed on by introduced mammals at the egg stage and some at the chick stage.

If those involved in the community project waited five years until they started trapping, they would have a much better estimate of how many New Zealand falcons there were in the Cardrona Valley, the rate of breeding success and the causes of breeding failure, Mr Parker said.

"If we find 80% of nests were lost to possums, then we could be much more targeted in our conservation and protection," he said.

Threats to karearea included introduced mammal predators such as possums, stoats, ferrets and cats; electrocution in electrical infrastructure; persecution by humans; nest disturbance and window strike.

The project was started by Cardrona Alpine Resort operations manager Ewan Mackie in 2019, prompted by watching the falcons at the ski field, but it quickly expanded to become a community project and the area surveyed now included most farms in the Cardrona Valley.

A nest site in Albert Town was included last year.

Mr Parker said future expansion could extend towards Glendhu Bay and Treble Cone, where there are known karearea.

Mr Parker said the birds might not have the same public profile as kea, but they were unique in their behaviour and there was no other pursuit and ambush predator like the New Zealand falcon anywhere else on the planet.

kerrie.waterworth@odt.co.nz

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