European settlement and acclimatisation
The arrival of Pakeha (Europeans) in the late 18th century accelerated environmental change and another cascade of extinctions in Aotearoa / New Zealand.
Introduction of new predators
When Cook arrived in Aotearoa, his ships brought Norway rats. Cats and mice established soon after, arriving with the earliest European settlers during the sealing and whaling era. Ship rats were later introduced around 1850 and are now the most common of rat species in New Zealand.
These predatory mammals spread rapidly and drove many species, which had survived the arrival of Māori, to extinction. Even the introduced kiore (Pacific rat) declined – outcompeted or preyed on by European mice and rats. Today in Aotearoa, kiore now only inhabit a few offshore islands and a handful of remote places in the South Island.
Rapid changes in land use
Early European settlers quickly exploited and overharvested the country’s rich natural resources, including seals, whales and timber. Kauri was recognised in the early 1800s as superb material for ships’ spars. This beautiful, durable timber later became high in demand for buildings.
During the 19th century, large areas of the northern kauri forests were milled and significant areas were also lost to wildfires. Miners modified the landscape in search of gold especially in the second half of the 19th century.
As the numbers of immigrants increased during the 19th century, large areas of native forest were cleared and wetlands drained for farming. This ‘breaking in’ of the land and conversion of indigenous wetlands, tussock grasslands, scrub and forest to pasture, reduced the former natural vegetation cover to only about a quarter of its previous extent.
In 1840, around 60 per cent of the land was covered in indigenous forest. Today, only 26 per cent of its original extent remains, with pasture and horticulture now occupying around 45 per cent of the country and exotic plantation forest covering 6 per cent of Aotearoa. Native scrub occupies less the 7 per cent of the country and wetlands have been reduced to 10 per cent of their original extent.
In addition to farm livestock, European settlers introduced many species of exotic plants and animals for utilitarian and sentimental reasons.
From 1830, rabbits were released as a food source and for their fur. They soon became pests, competing with farm livestock for pasture and eroding fragile soils with their burrowing.
Similarly, brushtail possums were introduced from south-eastern Australia and Tasmania in the 1850s to establish a fur industry. Aided by early protection, they became a serious pest species consuming pasture, ravaging native forests and preying on vulnerable native wildlife.
In a misguided attempt at biological control of rabbits, three species of mustelids (stoats, ferrets and weasels) were introduced in the 1880s. As predicted by experts at the time, mustelids only had a minor effect on rabbit populations but a devastating impact on native wildlife. Over the latter part of the 19th century, hares, hedgehogs and several species of wallabies were also introduced. They too became pest species.
Game species were also introduced including many species of deer, along with chamois and Himalayan thar. Goats and pigs became feral very early in the European era and herds of wild horses established in some places. These grazing and browsing mammals have greatly modified native forests, grasslands and alpine ecosystems, which had evolved for millennia in the absence of herbivorous mammals.
Trout, salmon and other exotic fish were introduced to rivers and lakes for recreational reasons, displacing and exterminating indigenous aquatic species through predation and competition.
Hundreds of species of exotic herbs, shrubs and trees from various parts of the world were introduced to farms, towns and gardens, along with about 40 species of mainly European birds. Some of these birds, such as the mallard, European blackbird, chaffinch and starling, are now among the most abundant bird species in the country.
While all these introductions have increased our country’s likeness to Britain and Europe, they have also altered Aotearoa’s ecology permanently and set it on a completely different evolutionary trajectory.