New Zealand Falcon

The New Zealand Falcon, known in Maori as karearea, is New Zealand's only endemic bird of prey and arguably its most thrilling. Where the far more commonly seen Australasian Harrier drifts lazily over paddocks, the karearea hunts like a fighter jet: fast, low, and agile, chasing other birds through forest and over open country in twisting aerial pursuits. Pound for pound it is one of the boldest raptors in the world, regularly killing prey heavier than itself and famously dive-bombing anything, including trampers and cyclists, that wanders too close to a nest.

This is a bird of striking contrasts. Females are considerably larger than males, a size gap typical of bird-hunting falcons. It ranges from wild alpine tussock and beech forest to, increasingly, exotic pine plantations and even vineyards, where some birds are actively encouraged as natural pest control. Once widespread, the falcon has declined through habitat loss, road strikes, electrocution on power poles, and predation of its ground nests by introduced mammals. The population is thought to be well under a few thousand pairs, and the bird is honored on the New Zealand twenty dollar note.

Karearea are compact, powerfully built falcons with relatively short, broad-based pointed wings, a long tail, and long yellow legs. Adults are dark brown above and heavily streaked below, with a blackish cap and a bold dark moustache stripe dropping from the bill. A bright yellow eye-ring and cere set off the large dark eye. The best identification clue is often behavior: fast, deep, purposeful wingbeats and direct, low pursuit flight, utterly unlike the slow flapping and long teetering glides of the harrier it is so often confused with.

Male vs. female

The sexes look alike in plumage but differ sharply in size, with females noticeably heavier than males. This difference, called reverse size dimorphism, is common among bird-hunting raptors and lets a pair exploit a wider range of prey: the smaller, faster male (sometimes called a tiercel) typically takes small, nimble birds, while the larger female can bring down heavier quarry. In the field, a lone bird is hard to sex, but a pair seen together, or a bird judged against a familiar prey species, often reveals the gap. Both sexes share the same dark, heavily streaked pattern and vivid yellow bare parts.

Juveniles

Juvenile karearea are darker and more uniform than adults, appearing almost blackish-brown above with less obvious streaking, and they lack the bright yellow bare parts of adulthood. In young birds the cere, eye-ring, and legs are a duller bluish or pale grey-green, brightening to full yellow as the bird matures. Freshly fledged young are noisy and conspicuous, begging loudly near the nest area and making clumsy early hunting attempts before they master the species' signature high-speed pursuit.

The signature sound of the karearea is a loud, rapid, scolding kek-kek-kek-kek, delivered insistently in alarm and most often heard when a bird is defending its nest, frequently while it repeatedly dives at the intruder. The sheer persistence and volume of this chatter is usually the first clue that a falcon is nesting somewhere nearby.

Between members of a pair, birds also give a drawn-out, wailing or whining note, and softer chittering contact calls are exchanged around the nest and during food passes. Away from the nest, karearea are often silent, so the harsh alarm rattle is by far the vocalization most people encounter.

The New Zealand Falcon is endemic, found nowhere else on Earth, and occurs across both the North and South Islands plus Stewart Island and several offshore islands. It is generally scarce and thinly spread, most numerous in the South Island high country, the central North Island volcanic plateau, and Fiordland. Researchers often recognize three loose forms tied to habitat: a bush falcon of forest, an eastern falcon of open tussock country, and a southern falcon of Fiordland and the far south.

Habitat is remarkably varied, spanning native beech forest and forest margins, tussock grassland, rugged hill and alpine country, and coastal scrub. In recent decades the species has adapted to human-modified land, notably exotic pine plantations, where the young trees mimic open hunting ground, and Marlborough vineyards, where a conservation program has shown falcons can help reduce grape-eating pest birds. Karearea are largely resident year-round, though some birds move to lower, more open country in winter.

Karearea are formidable bird hunters, catching most prey on the wing in a fast, low, surprise attack or a steep stoop. They readily take quarry larger than themselves, from small songbirds up to birds the size of pigeons, ducks, and introduced game birds, striking with the feet and killing with a bite to the neck. Their agility in tight forest is exceptional, allowing pursuits that few other raptors could manage.

The diet is flexible and shifts with what is locally available. Alongside birds, falcons take large insects such as cicadas and beetles, especially young birds learning to hunt, and they catch introduced mammals including mice, rats, rabbits, and hares. This adaptability is part of why the species has been able to colonize plantations and farmland as well as its ancestral wild habitats.

Unusually for a falcon, karearea almost always nest on the ground. Rather than building a structure, the female makes a simple scrape in soil or leaf litter, typically sheltered beneath a rock overhang, under a fallen log, among the roots of a tree, or on a protected cliff ledge or steep bank. This habit evolved safely in a land that, before human arrival, had no ground-dwelling mammalian predators.

A clutch of usually two to four reddish, blotched eggs is laid in spring, incubated mainly by the female for around a month while the male hunts and delivers food. Chicks fledge at roughly five to six weeks but depend on their parents for some time afterward as they learn to hunt. The ground nest that once kept eggs safe is now the species' greatest weakness, leaving eggs and chicks badly exposed to introduced cats, stoats, ferrets, and possums.

The karearea is a wild raptor you seek out rather than lure to a yard, and it is found only in New Zealand. The good news is that it is active by day, vocal near nests, and increasingly uses accessible modified habitats, so patient visitors have a genuine chance of an unforgettable sighting.

• Visit known strongholds such as the South Island high country, the central North Island volcanic plateau around Tongariro, and Fiordland, where falcons are most numerous.
• Scan over exotic pine plantations and their margins, especially areas of young trees and clearfell, which have become reliable modern falcon habitat.
• In Marlborough's vineyards, ask about the region's falcon conservation work, which has helped establish visible birds in the wine country.
• Listen for the alarm call, a loud, rapid kek-kek-kek, which often reveals a nesting bird long before you see it, then keep your distance to avoid disturbing it.
• Watch for the fast, direct pursuit flight low over open ground and learn to rule out the far commoner Australasian Harrier by its slow flapping and gliding.
• Consider a visit to a wildlife or raptor recovery center, such as Wingspan National Bird of Prey Centre near Rotorua, where captive karearea can be seen up close and flown.

• Australasian Harrier: A larger, longer-winged raptor that glides and scavenges, by far the most common bird of prey confused with karearea in New Zealand.
• Nankeen Kestrel: A smaller, hovering falcon that occasionally reaches New Zealand, paler and rufous above with a very different hunting style.