Rat (Norway) Rattus norvegicus
Species: Rattus norvegicus
Scientific name: R norvegicus
Common name: Norway or brown rat.
New Zealand has no native rats, but three kinds came with early sailors. They are the Pacific rat or kiore (Rattus exulans), the Norway or brown rat (Rattus norvegicus) and the ship or common rat (Rattus rattus). Polynesians introduced the rat around 1250–1300 AD, when they settled in New Zealand. Kiore are thought to have wiped out snipe-rails, owlet-nightjars, some small petrels, some native frogs, and all tuatara on the mainland.
The Norway rat is the largest of the two European rats. It is distinguished from the ship rat in that the tail, which is about 180mm in length, is thick and shorter than the body, which is about 200mm in length, and that the ear of this rat does not reach the eye when pressed forward. By contrast the ship rat, which is more common, has a tail larger than its body, and ears that cover the eyes when pressed forward. Both of the European species are associated with human activity and are found in houses, tips, waterways and cropland. Ship rats are highly fertile – one pair can produce a population of 3,000 in a year.
Kiore are now found only in Fiordland, Stewart Island and some off-shore islands. They were introduced to New Zealand by Maori settlers and have cultural and spiritual values to some Maori.
Rats have a major impact on New Zealand’s wildlife because they eat birds and their eggs and chicks, lizards, and invertebrates. They also eat a wide range of native fruits and other plant material, which puts them in competition with native wildlife for food.
Their droppings are cylindrical and stubby, sometimes tapering to a point. Norway rat pellets are about 16mm long, roughly twice the length of other rat pellets. Norway rats excavate burrows 60-90 mm in diameter, often beneath cover such as rocks or tree roots. They can excavate large volumes of soil, and often hoard food in their burrows. Pathways 50-100mm wide link burrows with feeding sites, and these paths can become well worn trails. The above information is from the Department of Conservation and Te Ara - the Encyclopedia of New Zealand.
A large male Rattus norvegicus held by a rat professional eradicator.
Photo of the Norway or Brown rat
Comparison of Rattus rattus and Rattus norvegicus
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