Pest animals remain a problem, particularly possums, rats and stoats, because they prey on native fauna, compete for food sources, and eat native vegetation. Other pests in Nelson’s hill country or Halo area include goats, deer and pigs. Feral and domestic cats pose a significant threat to native wildlife, particularly lizards and birds, and unrestrained dogs pose a threat to birds, particularly low feasting kereru, and weka.
Possums were first introduced to New Zealand in the 1800’s for use in the fur trade, from their native land of Australia. In New Zealand, however, there are no other animals which predate on possums to help keep them under control, and consequently they are a major threat to both our native wildlife and our native plants.
Possums are found in many environments, including suburban sections where they will raid fruit trees and compost bins, but in our forests, they feed off fledgling birds, eggs, and destroy trees through foraging.
Possums are known to have destroyed whole canopies of trees including totara, rata, titoki and kowhai. Evidence of their feeding can be seen by the litter of broken branches, leaves and half eaten fruits which are left on the ground. You may also see bite or scape marks on bark, usually a series of horizontal scars.
Control of possums is normally either by shooting/hunting or by trapping.
Stoat Trap. Photo: Corrin Walker Bain
The stoat was introduced to New Zealand as a means to control rabbits and hares in the 1800’s. They are now considered to be the main predator of our native birds, as well as possums, weta, lizards, hedgehogs and fish. Stoats will live anywhere that food can be found, and in a range of conditions including our forests and coastal landscapes.
Stoats will hunt at any time of day or night, and can have a home range up to 200 hectares. They are also strong swimmers.
Stoats are thought to be responsible for the extinction of some of our indigenous bird species such as the bush wren, the native thrush, and the laughing owl, and are a major source of the decline of the South Island kokako, the takahe, mohua, kakariki, kakapo, and kiwi species.
The control of stoats is normally through trapping.
There are three types of rat in New Zealand: the Pacific rat or kiore, the ship rat, and the Norway rat.
The Pacific rat was introduced by Maori settlers in New Zealand in the 10th century, while the Norway and ship rats were introduced by European settlement.
Rats have a significant impact on our wildlife as they eat both the birds and their eggs, and also compete with native wildlife for plant foods.
Although Norway rats are large enough to kill nesting seabirds that nest close to the ground, ship rats are the greatest threat as they are good climbers that can feed on birds nesting high in trees.
Evidence of rats can include the remains of seeds or other foods in hollow logs or in tree roots, and nests of loosely woven twigs and leaves can be sometimes found. Rat droppings may also be in evidence.
Control of rats is by trapping or poisoning.
Feral cats are known to cause significant damage to native wildlife. There are reports that cats are responsible for the elimination of entire populations of birds on off shore islands. For instance, cats were introduced into the Chatham Islands to control rabbits, but were responsible for the elimination of two species of sea birds and most forest birds on one island by the 1950s.
Do not dump unwanted kittens into the natural landscape.