Rats and mice (rodents)

Why are rats and mice a problem?

These rodents are a major threat to our region's biodiversity. They prey on birds’ eggs and young birds, eat seeds, fruits and seedlings and kill native lizards and invertebrates.

Rodents are also a common problem for people and businesses. They eat and damage crops, contaminate and damage human and animal food, damage buildings and carry diseases such as leptospirosis.

Rats and mice defecate and urinate as they travel, leaving urine stains and droppings.

Spot a rat or mouse? Here's what you can do...

About rodents

In New Zealand we have these rodents: 

• Norway rat (Rattus norvegicus)
• Ship rat (Rattus rattus)
• House mouse (Mus musculus)
• Kiore or Polynesian rat - thought to be extinct in the region

Norway rats are the largest, usually inhabiting waterways and coastal areas. They will also occupy buildings where there are suitable nesting conditions and an adequate food supply.

The ship rat and house mouse are the most common rodents in the Wellington region. They prefer drier habitats and forested areas including forests, dunes, rivers, lagoons and estuaries.

Rats and mice are prolific breeders. Each year a rat can produce up to 48 young, and a mouse up to 60 young.

Cats and dogs will not usually solve a rat or mouse problem and may only be successful in catching the odd one or two.

 What can I do?

Effective rodent control needs to be continual and should begin with prevention such as removing their food source and nesting grounds.

Prevention

The presence of rodents can be a sign that a clean up of the house, shed, garage or section is needed.

• Clean up inside. Rodents like old newspapers or magazines, boxes, rags and junk in cupboards, spare rooms and basements. Mice can live behind the refrigerator, in the hotwater cupboard, or in any kitchen cupboard. 
• Clean up outside. Rodents like piles of bricks, timber, rubble, derelict cars or appliances, piles of garden rubbish, and overgrown parts of the section.
• Rodent proof the compost. See the Predator Free Wellington easy guide, or use a sealed wormfarm.
• Cover food. Don’t leave bird or pet food out overnight where rats can get at it.
• Seal all entrances into buildings and keep areas around houses and buildings clear.

Control

Rats and mice can be controlled by trapping or poisoning. You can contact a commercial pest control operator or:

• Purchase kill traps and poisons from supermarkets, garden centres, hardware and farm supply stores, or online from Predator Free New Zealand and Good Nature
• Build your own backyard trapping tunnel. This tunnel plan from Department of Conservation is designed to protect your children and pets
• Get involved in a Predator Free group in your area and start rat control in your backyard

See Pest Control Methods for other ways to control rats and mice. You can also contact us for information on what control method best suits your situation.

More information:

• Greater Wellington rats and mice brochure
• Wellington City Council rats and mice brochure
• DOC information on backyard trappings - using them and benefits to trapping
• DOC rat trap videos - A video series on installing and servicing of rat traps used in conservation       
• Naturespace
• Predator Free Wellington
• Bionet - information about pests and disease in New Zealand