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May 2016 Issue
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Bird spotting: The harrier hawk

The harrier hawk is also known as kahu and swamp harrier. Photo: Matt Winter

The harrier hawk is one of three New Zealand birds of prey

Whether it be soaring and gliding high over a backcountry ridge or gently winging its way along a main highway searching for roadkill, the sight of a harrier hawk/kahu is common in New Zealand. Also known as a ‘swamp harrier’, it is a native species.

The harrier occupies a very wide ecological niche and is abundant throughout most of New Zealand, including the coastal fringe, estuaries, wetlands, pine forest, farmland and high country.

Although the plumage is highly variable, adults generally have a tawny-brown back, a pale cream-streaked breast and yellow eyes. Fledglings and juveniles have a much darker chocolate brown plumage all over. Females are slightly larger than males and the overall colour of both sexes becomes paler with age; older birds are almost a creamy white when seen from a distance.

Harrier hawks vocalise mainly as part of their courtship displays during the breeding season and create a series of same note, high-pitched, short and sharp ‘kee-o kee-o.’

Known for their dramatic ‘sky-dancing’ courtship, they start displaying these impressive manoeuvres as early as June and will continue with them through to October when the eggs are laid. The nests are bulky constructions comprised of sticks and are placed on the ground or on low bushes, in long grass, scrub or wetland. Nests may be added to over multiple seasons. Incubation and brooding are undertaken by the female with food provided by the male in dramatic aerial passes where the female turns upside down to take prey from the male.

Road-kill carrion such as possum, rabbit and hedgehog makes up a large proportion of their diet, especially during winter when other food sources are limited. Small- to medium-sized birds and mammals, insects, lizards and frogs are also targeted.

– Matt Winter is a Marlborough-based nature photographer

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