North Island Kōkako

The North Island kōkako (''Callaeas wilsoni'') is an endangered forest bird which is endemic to the North Island of New Zealand. It is grey in colour, with a small black mask. Adults have distinctive blue wattles. Because of its wattle, the bird is sometimes locally called the ''blue-wattled crow'', although it is not a corvid. The name "kōkako" comes from its vocalization. The song of the North Island kōkako has an almost human-like quality and can sound like its own name.

Visual identification

It is most immediately recognized by its unusual combination of elegant, dusky plumage and the vivid, fleshy blue wattles that hang prominently from either side of its beak.

The overall coloration of the North Island kōkako is a soft, slate-grey to smoky blue hue that envelops its entire body. This rich, velvety grey is subtly shaded and largely uniform, though colouring is slightly darker on the wings and tail. The feathers have a silky appearance and a very fine texture. The breast and belly are often a little paler than the back.

The face of the kōkako features a black facial mask that covers the area around the eyes and extends to the base of the bill.

The most notable feature of the North Island kōkako is its vivid blue wattles. These wattles are typically a saturated cobalt or ultramarine blue, with subtle purple tones, and they can vary slightly in shape and size among individuals. The wattles are thought to play a role in social signaling and courtship. Young, however, are born with pink wattles, which become a deeper blue as the bid matures. The wattles also play a role in thermoregulation, as they help dissipate body heat on hot days and retain heat in colder climates. When the North Island kōkako is warm, blood flow to the wattles increases, allowing heat to escape. When it’s cold, blood flow decreases, helping to preserve body warmth. Furthermore, the wattles can indicate the individual bird's health.

The bill is relatively short and curved slightly downward, black in color, and sturdy, suited to the bird’s omnivorous diet of fruits, leaves, and invertebrates.

The legs and feet are strong and bluish-grey to black, built for agility among tree branches. Kōkako are not strong fliers; instead, they are highly adapted for climbing and leaping through the forest canopy, using their powerful legs and claws to move through the dense foliage.

The North Island kōkako is a medium-sized bird, measuring about 38 to 40 centimeters (15 to 16 inches) in length, including a long, rounded tail that aids in balance and maneuverability. The tail feathers are dark and broad, often fanned out slightly when the bird is climbing or displaying.

Sexual dimorphism is minimal, though males tend to be slightly larger.

Threats and conservation

In the early 1900s the North Island kōkako was common in forests throughout the North Island and its offshore islands. The primary causes of decline were forest clearance by settlers and the introduction of predators such as rats, stoats and possums.

Unlike many of New Zealand's most vulnerable birds, kōkako survive in low numbers in several North Island native forests. However, research has shown that female kōkako are particularly at risk of predation as they carry out all incubation and brooding throughout a prolonged (50-day) nesting period. Years of such predation have resulted in populations that are predominantly male, with consequent low productivity rates.

Government-funded pest control programmes, and captive breeding programmes are critical to helping maintain population numbers on the mainland. A "research by management" approach has demonstrated that the kōkako decline can be reversed and populations maintained in mainland forests by innovative management of their habitat. Current research aims to increase management efficiency to ensure long-term kōkako survival. The use of biodegradable 1080 poison has been particularly beneficial in reversing population decline. For example, between 1991 and 1999 the breeding population of kōkako increased tenfold in Mapara Wildlife Reserve (Waikato) thanks to a series of four aerial 1080 operations. A population of kōkako has also been re-established at the Otanewainuku Forest in the Bay of Plenty.

New populations are also being established through releases on predator-free offshore islands. As a result, conservationists are hopeful for the species' long-term survival.

Distribution

As of 2010, North Island kōkako were present in Pureora Forest Park, Whirinaki Te Pua-a-Tāne Conservation Park, Mapara Wildlife Reserve, the Hunua Ranges, Ngapukeriki, Kaharoa Forest, the Te Urewera National Park, Puketi Forest, the Waitākere RangesRare kokako to sing in the Waitakere Ranges once again: http://www.forestandbird.org.nz/what-we-do/publications/media-releases/rare-kokako-sing-in-the-waitakere-ranges-once-again on the North Island and the Waimā/Waipoua Forests of Northland. Kōkako can be seen easily on a number of publicly accessible offshore island sanctuaries, including Tiritiri Matangi and Kapiti Island, where the regenerating forest is low enough to provide close views.

References

External links

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North Island kōkako
Birds of the North Island
North Island kōkako
North Island kōkako
Endemic birds of New Zealand