New Zealand kākā

The New Zealand Kākā: A Forest Dweller of Concern

The New Zealand kākā (Nestor meridionalis) is a prominent parrot species native to the indigenous forests of New Zealand's three main islands. This medium-sized parrot, measuring around 45 cm in length and weighing between 390 and 560 grams, is characterized by its predominantly brown, green, and grey plumage, accented by striking scarlet and orange flashes beneath its wings. The kākā shares its name with the extinct Norfolk and Chatham kākā, but the New Zealand variety persists, albeit in a vulnerable state.

Taxonomy and Evolution

First formally described in 1788 by Johann Friedrich Gmelin, the kākā was initially placed in the genus Psittacus before being reclassified into the genus Nestor. It is closely related to the kea, with which it diverged approximately 1.72 million years ago, developing a more specialized affinity for forested environments compared to the kea's adaptation to alpine habitats. The kākā belongs to the ancient parrot superfamily Strigopoidea, an early evolutionary split from other parrot families. Two subspecies are recognized: the North Island kākā (Nestor meridionalis septentrionalis) and the South Island kākā (N. m. meridionalis), though recent research questions significant genetic differences between them.

Description and Distinctive Features

Beyond its striking plumage, the kākā possesses a robust beak that is intermediate in length and sharpness between its relatives, the kea and kākāpō. Evidence suggests sexual dimorphism in the North Island kākā, with males exhibiting larger bills, possibly an adaptation for accessing deep-seated food sources like wood-boring larvae, which they provision for females and hatchlings.

Distribution and Habitat

Historically widespread, the New Zealand kākā now primarily inhabits lowland and mid-altitude native forests, favoring mature forests with complex canopies. Its distribution has significantly contracted due to habitat modification and predation. Strongholds are found on offshore islands such as Kapiti Island, Codfish Island/Whenua Hou, and Little Barrier Island. Reintroduction programs, notably at Zealandia in Wellington, have shown success in increasing local populations and enabling mainland recolonization.

Behavior and Diet

Primarily arboreal, kākā are highly active and gregarious, often seen in flocks. They exhibit complex social behaviors, including social play such as chasing and mock fighting, which contribute to cognitive development and social bonding. Their diet is remarkably varied, adapting to seasonal availability. They consume fruits, berries, seeds, flowers, buds, nectar, sap, and invertebrates. A notable feeding behavior is sap feeding, especially during winter and spring, where they access nutrient-rich sap by gouging or scraping bark. Their specialized brush tongue is adept at lapping up nectar and honeydew, crucial high-energy food sources.

Breeding Habits

Kākā are monogamous and typically nest in hollow trees. The female incubates the clutch of typically four eggs (ranging from four to eight), while the male provides food. The incubation period lasts about 24 days, and the chicks fledge after approximately 70 days. Both parents care for the fledglings.

Conservation Concerns

The New Zealand kākā is classified as vulnerable due to significant population declines. Introduced predators like stoats and possums pose a major threat to nesting adults and young. Habitat loss and competition from introduced species, particularly wasps for honeydew, further exacerbate their precarious situation. Conservation efforts, including predator control through trapping and aerial application of toxins, have demonstrated positive impacts on kākā population recovery in treated areas.