Types of konihi (predators) in Aotearoa
Kiore (rats) are a major threat to Aotearoa’s native plants and animals. They are omnivores so their eat almost everything, including birds, bats, invertebrates, lizards and insects, as well as flowers, seeds and fruits. They can live in many different environments, particularly liking areas around humans. They breed rapidly which makes their populations large and hard to control. There are two key main species that are found nationwide:
Norway rats 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 preying on nesting birds and their eggs and chicks. They can be recognised by their short, thick tail and small ears.
Ship rats climb trees and invade the nests of many native birds. They have bigger ears and a long tail which they use to climb the rigging of ships that brought them to Aotearoa and also use to help them balance on branches.
Paihamu (possums) are spread across Aotearoa and found in places with shelter and good food supply. They are nocturnal, live in trees, and eat 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. This makes it important to control their numbers. Possums are about the size of a cat and have a bushy grey/black/brown coat and tail. They are marsupials which means the females have a pouch to carry their young.
Mustelids
Wīhara (weasels) are the smallest and the least common mustelid but are still a threat to wildlife. They have a red/brown coat colour and a short tail. They mostly eat mice but also hunt birds, eggs, insects and lizards. They are often found in gardens, farmland and scrub. Weasels are are nocturnal. Baby weasels can be effective hunters at only 8 weeks old.- Toriura (stoats) have a black/brown coat, pale belly and a bushy tail with a black tip. They are bigger than weasels but smaller than ferrets. Stoats are considered the biggest threat to our native bird populations because they are skilled hunters. They thoroughly check burrows and hollows to find nests and hunt at day and night. Their good eyesight, hearing and sense of smell means vulnerable birds have little chance of survival. They also breed rapidly with a female stoat able to get pregnant from 2-3 weeks old and mother has 4-6 babies at a time.
- Tori hora (ferrets) are about the size of a small cat and 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-based kiwi and weka, birds that live in trees, and coastal species like penguins.
Feral cats are one of Aotearoa’s apex predators which means that nothing preys on them. We need to try and lower their 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 these places. In city areas, the decline of native birds is mainly caused by pet cats.
Hetiheti (hedgehog) are prey on wētā, skinks, eggs and chicks, though they also eat garden pests like slugs, snails and grubs. They can be found across Aotearoa and can eat 160g of invertebrates every day. One hedgehog was found with 283 wētā legs in its stomach. Hedgehogs are covered in spines and use 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, European settlers brought 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. Other insects and lizards such as wētā and tuatara were put under threat from these species. Humans also caused the extinction moa, large birds which were 2.3m and weighed up to 230kg.
There were also some predator species that were purposefully introduced. Rabbits were brought into Aotearoa be hunted for game, but their populations exploded and they cause significant damage to the land and native plants. Stoats were then introduced to 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 50-70 million at the peak of their population in 1980. Hedgehogs were another purposefully introduced species, this time to help European settlers to feel more at home. They also quickly became a big threat to our native ecosystems.
What is Predator Free 2050?
Predator Free 2050 is a nationwide goal to eradicate all rats, possums and mustelids (stoat, ferrets and weasel) from New Zealand by 2050. It is these introduced predators that inflict the most harm on Aotearoa’s native wildlife and plants. 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 remove 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.