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Study suggests two types of native falcon

NZ Newswire logoNZ Newswire 10/08/2016

New Zealand's native falcon, the karearea, is actually two types of bird, according to a Massey University study.

A paper published in IBIS, the International Journal of Avian Sciences, suggests there are two subspecies of karearea, and the boundary between the two distinct lineages coincides closely with Cook Strait.

The karearea, which features on New Zealand's $20 note, is the country's only surviving endemic raptor and is found in the North Island and South Island, and the Auckland Islands.

The paper's authors, Professor Steven Trewick and postgraduate student and falcon enthusiast Lena Olley, examined the body sizes and neutral genetic markers of the falcon.

Prof Trewick says karearea vary considerably in size and colouration, over and above the differences between the males and females that are typical of raptors.

He says this variability has caused confusion since its earliest observation in the 1870s.

"Differences in size and other attributes among spatially separated populations could represent adaptation to local conditions," he said.

"By recognising two distinct subspecies in karearea, we will be able to identify the patterns of diversity within the species and understand the distinct evolutionary ecology of each."

Prof Trewick said North Island falcons strongly associated with native forests, while South Island ones associated more with open habitats.

He said the finding supported informal conservation management strategy to avoid the crossbreeding in captivity of falcons from the two islands.

The Department of Conservation estimates there are between 5000 and 8000 karearea left, although this number is uncertain.

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