Getting on top of animal pests

Bush remnants can host animal pests, which cause significant damage to both native plants and animals. Animal pests can have a staggering impact on our natural ecosystems by:

  • Eating or damaging native plants. In some places, pest browsing of particular species can significantly change the make-up of a forest.
  • Eating the annual seed crop of some plants, preventing natural regeneration.
  • Eating seedlings, preventing regeneration and opening up the understorey to weed invasion.
  • Killing native birds and animals.
  • Destroying nesting sites and depleting food sources for native birds.

Regular control of animal pests is an essential part of successfully protecting your bush remnant. It is not a one-off job, so you’ll need to schedule pest control in your ongoing work programme.


Possums are a significant threat to bush, causing considerable damage to trees, shrubs and seedlings. They also carry bovine tuberculosis, posing a threat to agriculture. While it is almost impossible to completely eradicate possums, regular control will reduce local populations to less damaging levels. In most areas, ongoing possum control will be necessary because of re-invasion. If you can afford nothing else, possum control is essential and will have the biggest positive effect on the condition of your bush.

There are a variety of control methods available, each with their own benefits and tradeoffs. Using poison bait stations can be an effective low-input control method. Traps are higher maintenance, but once you’ve purchased them the only cost is your labour. Night shooting around forest / pasture margins can also help. Talk to the Biosecurity staff at Greater Wellington for advice on which methods would be the most useful in your situation.

Rats and mice

Rats eat small animals, eggs and young birds, as well as a wide range of native fruits and seed. If you want to encourage native wildlife in your bush remnant, rat and mouse control will be necessary.

The best way to deal with rats and mice is by poisoning using bait stations. The best time to bait your traps is between spring and summer to protect birds over their breeding season, when they and their eggs are most vulnerable to predation from rats. Talk to the Biosecurity staff at Greater Wellington for more information.

Weasels, stoats, ferrets and cats

Mustelids (weasels, stoats and ferrets) and cats can have a devastating effect on native birds, eating both adults and their young. Stoats and cats are the most numerous and widespread.

Controlling rats, mice, stoats, ferrets and cats will help keep your bush block a healthy habitat for native birds and animals. Most of these pests can be targeted together with certain poisons, but each requires a different trapping method if poisons aren’t used. You’ll need to make sure your traps are approved by the SPCA. Contact Greater Wellington Regional Council for advice about the best methods for your property.

Goats, deer and pigs

Feral goats and deer can make short work of young seedlings and damage the leaves and bark of trees up to around two metres high. They will get through most fences! Pigs can destroy years of seedling regeneration in a very short time. Shooting is the most common control method for goats, deer and pigs. Professional hunters can be hired to eradicate or control feral pest animals.


Recent studies by Landcare Research indicate that hedgehogs are not the benign snuffling creatures that many of us may have thought. Hedgehogs are a potentially serious threat to endangered native skinks and invertebrates (animals without a backbone). They are also known to predate on the eggs and chicks of ground-nesting birds. Landcare Research scientists suggest laying traps for hedgehogs at the beginning of the birds’ breeding season, when hedgehogs may be at their most damaging, and in the autumn, when female hedgehogs can be specifically targeted.