Why are some animals a pest?
New Zealand has been separated from other land masses for over 80 million years. During this time our native wildlife and plants learned to live without land mammals. The only mammals living here at that time were bats.
When people came to New Zealand, they brought land mammals. Sometimes this was deliberate (for example, rabbits). Sometimes animals were brought by accident (for example, ship rats). These animals have led to a loss of native plants, birds, reptiles and invertebrates.
In many parts of the country these introduced animals are now pests.
What do animal pests do?
Pests such as possums, rats, feral cats and stoats compete with our native birdlife for food and habitat. They can eat the eggs and young and attack the adults. They also affect other species, including reptiles and insects. These animals are often called predators.
Larger pests such as goats and deer can damage native forests by feeding on forest plants, trees and seedlings. Forests can’t grow back when all the young seedlings are eaten. Pigs stop forest growth by digging up the forest floor in search of grubs and roots.
Find out more about the different animal pests in New Zealand.
Weeds
There are now more introduced plant species growing wild in New Zealand than native plant species. Weeds are a threat to some native animals because they:
- change or destroy their habitat
- reduce the amount of food or breeding sites
- change the way animals behave.
Weeds can take over and change habitats that were once good for native species.
Where do weeds come from?
Most of New Zealand’s weeds were brought in to New Zealand as garden plants.
Most of the spread of weeds in New Zealand is because of people. They bring in new plants that spread and dump garden waste in bush reserves.
People
People can have a large impact on the environment. Before people arrived in New Zealand, the land was covered in bush. But three-quarters of it has been burned or cut down. Over 90 percent of New Zealand’s wetlands have been drained or filled. Many of our lakes and rivers now have poor water quality.
Just a few changes in the way land is managed can make a big difference. Some of the major threats to our environment caused by human activity include:
- removal of water for irrigation and water for animals
- reduced water quality from sediment and nutrient farm run-off
- removal of forest and native plants
- reclaiming land
- more houses, bigger cities and less wilderness
- damage from vehicles, rabbits, hares and farm animals
- climate change from increased use of fossil fuels
A BioBlitz can help. Before we can help restore biodiversity to an area, we need to know what naturally lives in that area and what pests need to be removed.
Ready for a quiz? Try the "Threats to Biodiversity" interactive activity.
