Whereas larger birds were most vulnerable to human hunting, smaller birds, bats, reptiles and fish were vulnerable to kiore, other rats and larger predators. The main threats facing plants have been land clearance and browsing mammals.
New Zealand wrens
The smallest birds to become extinct were four species of the distinctive New Zealand wren (not related to northern hemisphere wrens). Three species were flightless, and would have scurried around in forest and scrub like two-legged mice.
Wrens were vulnerable to kiore (Pacific rats). Two species – the long-bill wren and the stout-legged wren – disappeared. They disappeared long before European settlers arrived.
The Stephens Island wren, once found all over New Zealand, had a last stronghold on kiore-free Stephens Island. It was safe until cats arrived and the forest was removed in the 1890s, and was last seen in 1895.
The bush wren or mātuhi (a 16-gram bird that was able to fly) gradually dwindled in mainland forests. It was last seen at Nelson Lakes in 1968. Rats from a boat invaded its last island refuge, Big South Cape Island (Taukihepa) in 1962. These rats also caused the extinction of the greater short-tailed bat and the South Island snipe.
Both the North and South island species of piopio were plentiful when European settlers arrived, but were extinct by the early 20th century. Related to the Australian whistler group, piopio were skilled songsters that could mimic other species. They were known as ‘native thrush’ as they resembled thrushes, with brown upper parts and (in the South Island bird) flecked under parts.
The huia has come to symbolise the tragedy of New Zealand extinctions. Greatly significant to Māori, this glossy black bird had white-tipped tail feathers and orange-red wattles, and a deep, melodious call. The female’s bill was long, slender and down-curved, while the male’s was shorter and pick-like. Huia did not fly often. Usually they sprang about on their long legs.
Māori valued their tail feathers, worn on special occasions by people of high rank, and stored in carved wooden boxes.
The rapid decline of huia was noted after new predatory mammals were introduced in the 1890s. The last (unconfirmed) sightings of this mystical bird were in the 1920s.
Greater short-tailed bat
One of New Zealand’s three bat species gradually disappeared on the main islands, surviving on Big South Cape Island (near Stewart Island) until it was invaded by rats in the 1960s.
New Zealand had many skinks and geckos, as well as two species of tuatara. An unknown number are extinct – their skeletons are less durable or identifiable than those of birds.
The world’s largest known gecko, kawekaweau, measured 60 centimetres (including the tail) and featured in Māori legend. It was last reported in the Urewera in 1870, and the only likely specimen is held at a French museum.
Over 90 species of skink and gecko remain, but about 40% survive only on rat-free offshore islands. Many species on the mainland are threatened by rats, cats, dogs and stoats.
Three extinct frog species are known. There are four living species, two of them confined to small islands.
The grayling or upokororo was an important fish in streams and rivers, and a useful food during Māori and early European times. It went rapidly from abundant to rare between the mid-19th and early 20th centuries, and is now presumed extinct. This may be linked to the introduction of trout into rivers and lakes, but grayling also vanished from trout-free waters.
There is little evidence of New Zealand plant extinctions since human settlement. The slide towards extinction tends to be slower than for animals – plants may be damaged by browsing, but still continue to breed. Some dangers to plants, such as fire, are restricted to a local area, unlike predators which can travel widely and use scent to track their prey. Other processes affecting plants are gradual rather than sudden. But without intervention, more plants will be lost in the long term.
Four plants are known to have become extinct in recent times. The best-known is Adams mistletoe. It suffered a reduced habitat, loss of the birds that pollinated it and dispersed its seed, browsing by possums, and over-collecting by plant enthusiasts.
Another extinct New Zealand plant is Lepidum obtusatum, a species of coastal cress.
Many more plants are threatened.