There are 4 rodent species in New Zealand. These small mammals have caused serious problems to native wildlife, such as birds, lizards, and insects.
I live in the Taranaki area of the north island of New Zealand. Unfortunately, I’ve seen first hand just how abundant these rodents now are. I’ve seen them all around my house, running along fences, climbing trees, and on the ground. There are 4 rodent species in NZ, but I’ve only seen two around our house – the mouse and ship rat. Here is a bit about these 4 rodent species, including how to identify them.
The 4 Rodent Species In New Zealand
Kiore or Polynesian Rat
This was the first of the four species of rodents to come to New Zealand. It came here in the first canoes of the early Polynesian settlers about 750 years ago. They used to be very widespread, but the arrival of the other rodents around the time of the Europeans pushed them down to Fiordland and some offshore islands.
House Mouse
The house mouse became established in the north island around the 1830s and made it to the south island in the 1850s.
It is now common all over New Zealand in all habitats from the beach up to the mountains.
This grey/brown mouse is by far the smallest of the rodents, measuring 100 mm and weighing 28 g.
Brown or Norway Rat
This rat goes by many names, none of which are too flattering. It’s known as the swamp rat, sewer rat, or the brown rat.
It was introduced to New Zealand in the 18th century and was quite common by the 1850s. However, it is now found only in wet habitats, urban areas, and some offshore islands.
The Brown rat is the biggest of the rodents, weighing up to 450 g and measuring up to 275 mm. This is best distinguished from the ship rat by the length of the tail. The tail of the brown rat is shorter than its body.
Black or Ship Rat
The ship rat was first introduced to the north island in the 1860s and the south island in the 1890s.
The ship rat is now the most common rat and the biggest pest in New Zealand. It can be found all over the country in huge number in some areas.
This is a large rat weighing up to 215 g and measuring up to 230 mm. It is most easily distinguished from the brown rat by the length of its tail, which is much longer than its body. It also has very large ears, which will cover its eyes when pulled forward.
The ship rat is a good climber, often climbing trees to get to bird nests. This is what makes it such a threat to native species as it eats bird eggs, and chicks.