Rats are only considered pests in the site-led programmes in Dunedin. Not only do they nibble away at your cheese, they also eat our native plants and animals, in particular birds and their eggs, lizards and invertebrates (animals without a backbone or bony skeleton). They can eat massive amounts of native seeds meaning less native plants grow. Rats will eat whatever they can find and eat 10% of their body weight a day which also means they are in competition with other species for food. Norway rats start breeding as young as 3-4 months old and can have 15-20 babies per year.

There are three types of rats in our pest plan.

Ship rats are the most common rat in New Zealand. They are slim with large hairless ears and are either black all over or grey-brown fur on their back with a creamish-white belly. The adults usually weigh about 120-160g but can be over 200g. Their tail is longer than their body. Pest Detective have more information on ship rats here.

Norway rats have brown fur on their back and pale grey fur on their belly. They are much larger than ship rats, with adults usually weighing 150-300g but can be over 500g and up 390mm long. Unlike the ship rat, their tail is shorter than their body. Pest Detective have more information on Norway rats here.

Kiore is the Māori name for the Pacific or Polynesian rat. They have brown fur with white-tipped grey fur on their belly, and pale feet with dark markings on the outer edge of their back feet. They are smaller than to other rats in New Zealand growing to a maximum length of 180mm (not including their tail) and they usually weigh about 60-80g but can get up to 180g. Kiore are sometimes confused with ship rats and a way to tell them apart is that their tail is shorter than their body. Pest Detective have more information on kiore here.

There are no rules for landowners in Otago’s pest plan regarding rats. Under the plan rats are only classified as a pest in the site-led areas; Otago Peninsula, West Harbour/Mt Cargill, Quarantine Island and Goat Island. See our site-led programmes page for more on what this means.

The goal is to assist communities to undertake sustained control of rats in these areas to prevent or improve on damage to the indigenous ecosystem values at these sites.

RC will take a lead role in supporting the goals of community groups and agencies in site-led areas in relation to rats. This may be through advice, education, funding, service delivery or requiring landowners to undertake control when needed.

Trapping is the main method for rat control.