Types of konihi (predators) in Aotearoa
Kiore (rats) are a major threat to Aotearoa’s native plants and animals. They are omnivores so their diet is hugely varied from birds and bats, to invertebrates, lizards and other insects as well as flowers, seeds and fruits. They can live in a diverse range of environments, particularly liking urban areas around humans, and breed rapidly making their populations large and hard to control. There are two key rat species that are found nationwide:
- The Norway rat are good swimmers and can swim up to a kilometre. They can climb trees but tend to spend most of their time on the ground targeting ground nesting birds and their eggs and chicks. They can be distinguished by their short, thick tail and small ears.
- The Ship rat is arboreal which means they are able to climb trees and reach the nests of many native birds. They are characterised by bigger ears and a long tail which they once used to climb the rigging of the ships that brought them to Aotearoa and now use to assist with balancing in the branches.
Paihamu (possums) are spread across Aotearoa and found in places with shelter and good food supply. They are nocturnal, live in trees, and target eggs and chicks of many of our endangered native birds. They also eat nectar and berries, which reduces the food supply for other wildlife, and spread diseases to cattle so population control of these predators is very important. Possums are similar in size to a cat and can be identified by their bushy grey/black/brown coat and tail, they are marsupials which means the females have a pouch.
- Toriura (stoats) have a black/brown coat, pale belly and a bushy tail with a black tip. They are smaller than ferrets but bigger than weasels. Stoats are considered the biggest threat to Aotearoa native bird populations because they are hunters by nature, thoroughly checking burrows and hollows to find nests and doing so day and night. Their good eyesight, hearing and sense of smell gives vulnerable birds little chance of survival and even prey on other pests such as rats, mice ad possums. They are also rapid breeders with a female stoat able to get pregnant from 2-3 weeks old and mother 4-6 babies at a time.
- Tori hora (ferrets) are about the size of a small cat so are larger than both stoats and weasels. Although not as widely spread as stoats, they can still be found across Aotearoa, especially in open country such as farmlands, the edge of forests and coastal areas. Their preferred prey is rabbit but native species are still vulnerable including ground-dwelling kiwi and weka, native birds that nest in trees, and coastal species such as penguins.
- Wīhara (weasels) are the smallest and the least common mustelid but are still a threat to wildlife. They have a more red/brown coat colour and a short tail. Their main food source is mice so they frequent similar habitats to their prey such as gardens, farmland and scrub but are known to also hunt birds, eggs, insects and lizards. they are nocturnal and even baby sweals can be effective hunters at only 8 weeks old.
Feral cats are one of Aotearoa’s apex predators which means that they aren’t preyed on so we need to try and minimise their population numbers and impact. Like stoats, they are skilled at hunting many native wildlife such as bats, birds, lizards and insects. To try and control rabbit numbers, cats were introduced to 30 offshore islands in Aotearoa but luckily they have now been removed from over half of those islands. In city areas, the decline of native birds is mainly caused by pet cats.
Hetiheti (hedgehog) are widely considered to be quite cute but are actually lethal predators of wētā, skinks, eggs and chicks, with their diet also consisting of other garden pests such a slugs, snails and grubs. They can be found across Aotearoa and known to eat 160g of invertebrates every day, with one hedgehog found with 283 wētā legs in its stomach. Hedgehogs are covered in spines and rely on these for protection. They are nocturnal creatures who find most of their prey by smell and hibernate in winter in dens under logs, dry litter or in burrows.
How and why were predators introduced to New Zealand?
Predators were introduced by settlers who arrived to New Zealand in two waves. The first wave of settlers were Polynesians who brought with them the kiore (pacific rat) and the kuri (dog). By the 19th century the second wave of European settlers had arrived bringing with them other rat species (Ship and Norway rats), ferrets, weasels, stoats and cats. Many of our flightless and ground-nesting birds (such as the kiwi) proved easy targets when these never before seen predators were introduced to the Aotearoa ecosystem. Other insects and lizards such as the wētā and tuatara were put under threat from these species and humans themselves also caused the extinction of large birds which were 2.3m and weighed up to 230kg, called Moa.
There were also some predator species that were purposefully introduced. Rabbits were brought into Aotearoa to provide game for sportsmen to hunt but their populations exploded and they cause significant damage to the land and native plants. Stoats were then introduced to try and control the rabbits, but they quickly became the most destructive of all the introduced predators. Possums were introduced by Europeans to create a fur industry in Aotearoa, and although they initially did not survive eventually spread across the country with around 50-70million at the peak of their population in 1980. The Hedgehogs were another purposefully introduced species, this time to help European settlers to feel more at home, but quickly became a big threat to our native invertebrates, such as wētā.
What is Predator Free 2050?
Predator Free 2050 is a nationwide goal to eradicate all mustelids (stoat, ferrets and weasel), rats and possums from New Zealand by 2050. It is these introduced predators that inflict the most harm on Aotearoa’s native wildlife and plants, and in order to give vulnerable species a fighting chance and maintain the native species that remain, we must act now. Some of our offshore islands are already Predator Free which is a good start but Predator Free Wellington is trying to eradicate these species from an urban landscape where people live, work and play every day. There are several similar projects across Aotearoa as well as thousands of backyard trappers committed to this eradication mission.