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If a contest were held to determine the most impressive tree species in the world, it is possible that the kauri would win. It attains heights of 147 to 180 feet (45-55 m) and girths of 65 feet (20 m). As the tree grows, it sheds its lower branches, leaving a massive gray trunk extending upwards for 98 feet (30 m) before spreading into a large crown. While few areas with continuous kauri canopy remain, the trees are so striking and impressive that any area with kauri trees is usually referred to as kauri forest. In these unique forests, rare bird species--such as the kokako and kiwi--can be found.
This warm, humid region is very different from the rest of North Island. There are no high mountains, and the landscape is generally subdued. Heading south into the Auckland province, the land begins as steeply rolling country and relaxes into the gently rolling Waikato Basin. Vegetation here was once mostly kauri warm-temperate forest. Kauri trees can live 2,000 years and have been heavily exploited by the timber industry over the past 200 years. Large portions of forest have been cleared to gumland scrub and then to pasture. Vegetation is normally found in tiers. An upper layer of conifers grows in some areas, either as scattered trees or in a thick, continuous formation. This tier includes kauris and podocarps. A lower tier can be found only if the upper tier is not continuous. The density of this second tier increases as the density of the first one decreases. The second tier includes tree ferns and nikau palms, transitioning into a layer of saplings and shrubs. Further down, a tall herb layer consists of large ferns growing over filmy ferns, mosses, liverworts, and orchids. Many interesting birds are found in the kauri forest. Only 100 kokakos, an endemic species of wattlebird, still live here. A kokako has a bright blue, fleshy wattle, a black beak, and gray feathers. Other interesting birds that live in kauri forest include kiwis, red-crowned parakeets, and two endemic species of parrot, the kaka and the kakapo. The distinctive kiwi--a round, flightless bird with a long thin bill--is the national emblem of New Zealand. Brown kiwis can still be found here, but little spotted kiwis are confined to offshore islands, where they are safe from predators. The kakapo is a nocturnal flightless parrot that has been completely eliminated from the North Island by predators, surviving only offshore on Little Barrier Island. New Zealand’s only indigenous terrestrial mammals, the short-tailed and long-tailed bats, can be found in this ecoregion too. On the ground, kauri snails can travel several hundred feet in one night, a fast clip for a snail. Wetas--giant grasshopper-like insects endemic to New Zealand--begin to crawl around late at night. They were once the main prey of the tuatara, the sole survivor of a group of reptiles that existed 200 million years ago, alongside dinosaurs. Tuatara populations have decreased greatly since the introduction of Polynesian rats and are now only found on scattered, predator free, offshore islands.
When Polynesians first arrived 800 years ago, they brought the first mammalian predator, the Polynesian rat, with them. Later, Europeans introduced more mammalian predators such as ferrets and stoats. New Zealand’s native species evolved for 80 million years in the absence of mammalian predators after splitting off from the supercontinent Gondwana. As a result, many endemic birds are flightless and completely defenseless against humans and the predatory animals that came with them. Today, introduced predators are a serious threat to bird species, while other introduced species (such as possums) devour the native vegetation. Logging, grazing, and development also pose problems. For more information on this ecoregion, go to the World Wildlife Fund Scientific Report. All text by World Wildlife Fund © 2001
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