Why control rats and mustelids?

To avoid damage to homes and property

Rats like to nest in warm, dry places – like your roof space. They can chew through many building materials, including insulation, electrical wires and/or water pipes, causing damage and flooding.

To reduce health risks

Rats can carry diseases such as Leptospirosis, Salmonellosis and Rat Bite Fever. They can also carry parasites such as fleas, mites and ticks.

To give our wildlife a chance to survive

Most of New Zealand’s native wildlife including birds, lizards and invertebrates are not found anywhere else in the world, and yet their numbers are declining at an alarming rate. New Zealand has the highest rate of threatened species in the world. More than half our native animal species are currently at risk or threatened. One of the biggest reasons our native wildlife isn’t surviving is introduced mammalian predators like rats and stoats are killing them, and our wildlife is unable to defend itself.

DOC’s Threatened Species Ambassador Nicola Toki explains it best “True kaitiakitanga and guardianship of our native wildlife is making sure that our birds, reptiles and invertebrates have a safe place to live. The key to getting it right is to hold onto empathy for other living things along the way.”

Read the full article



Mustelids include weasels, stoats and ferrets. Stoats are the most common of these threes species on Waiheke. All Mustelids are good swimmers and stoats can also climb, they prey on animals up to three times their own body weight.

Telling these three species apart can be difficult. Read more about stoats here.



Ferrets are larger (up to 1.5kg) and usually have a dark facial mask and creamy coloured body, with dark guard hairs giving an overall darker appearance. Ferrets are nocturnal.

Stoats and weasels

Stoats and weasels are cinnamon coloured with a white underbelly, with stoats being larger and with a black tipped tail. Stoats and weasels seen to hunt during the day.


There are two main species of rat on Waiheke - the ship rat and the Norway rat. Both are rapid breeders. A typical rat will be 15 to 20cm long with a further 20cm of tail. Read more about rats here.


Ship rat (Rattus rattus

  • Very long tail - in adult this is longer than the head and body length combined.

  • Very long thin ears - when you pull the ears forward they will generally cover the eyes of the rat.

  • Smaller of the two rats, weighing around 150g.

Norway rat (Rattus norvegicus) 

  • Thick tail usually shorter than head and body length.

  • Small ears that can’t be pulled forward over the eyes.

  • Large, robust rat, weighing up to 500g.

Predator control

Controlling predators on your property:

  • Identify your predator.

  • Choose an appropriate trap or bait (ensure bait is used in bait stations).

  • Place traps or bait stations outside.

  • Check traps regularly and/or “pulse” your bait programme.

  • Join in with neighbours for better results!

First identify which predator (rats or mustelids) you want to control and then choose the most appropriate control method. We advocate for the use of approved predator control tools. Take care to read instructions before use, and avoid non-target animals getting caught in traps or finding bait by placing traps in approved trap boxes and baits in lockable bait stations.

Rats – are generally controlled using traps or bait (toxin) in bait stations.

Mustelids – are generally controlled using traps.

If you live on a suburban section, you’ll probably only need to target rats. However, if you live on a larger lifestyle block or a section that is near a bush reserve or along the coastline of Waiheke you may need to control rats and stoats.

When choosing a location for your trap or bait station remember predators are often found near water and food sources such as fruit/nut trees,  compost bins, chicken houses and will use a fence line or edge of a building as a pathway to move along.