Pests

Ship Rat

Summary & Description

Species: Rattus rattus
Origin: Europe
Breeding Cycle:
Diet: Birds, eggs, plants, invertebrates
Home Range (ha): 0.01 - 0.02
Average Length (mm): max. 225
Average Weight (g): 120 - 160

Originating in India, the ship rat spread throughout Europe and the UK, making it’s way to NZ some 200 years ago with the arrival of Europeans. The ship rat quickly displaced the Norway rat as the most common and widespread rodent in NZ. They are identifiable by their large ears and a long tail.

Biology & Ecology

Ship Rat skull.

Ship rats spend a large amount of their time in trees, their arboreal nature allowing easy access to birds' nests. They have a varied diet, eating a wide variety of native and introduced birds, plants, and invertebrates.

Ship Rat poo.

They are efficient swimmers, establishing populations on pest-free islands up to 750 m away.

Threat & Impact

Ship Rat eating a kiekie fruit.

NZ robin eggs are consumed by ship rats.

What you can do

Use Detector cards to locate the best trapping site.

Rat control can be done by everybody, no matter how big your backyard. Establishing a good network of traps around your sensitive sites Getting an understanding of rat locations is important so be sure to set out detector cards before setting your trap.

Goodnature A24 Rat & Stoat trap.

By detecting, not guessing, you can quickly locate rat populations and tailor your pest control. Be sure to place your traps a distance from food sources like compost.

Norway Rat

Summary & Description

Species: Rattus norvegicus
Origin: Europe
Breeding Cycle:
Diet: Birds, eggs, plants, invertebrates
Home Range (ha): 0.01 - 0.02
Average Length (mm): 184 - 192 mm
Average Weight (g): 150 - 300

New Zealand was virtually mammal free prior to the arrival of pacific islanders around 700 years ago, with them came the pacific rat or Kiore. Nearly 250 years later, Europeans brought the ship rat and the Norway rat. Of the three species, the Norway rat is the largest and is most easily identified by their short tail and small ears.

Biology & Ecology

Rat Skull.

Commonly found in waterways and in urban areas, Norway rats are efficient swimmers and are sometimes referred to as the "water rat". They have been known to swim passages greater than 600 m. Able to climb when required, they are more likely to

Cylindrical (Pastille shaped), avg 16 mm long.

be found in burrows around populated areas and buildings. These rats are omnivorous and take an opportunistic approach to food. The average adult Norway rat eats around 10% of their body weight per day.

Threat & Impact

Rat scavenging.

Southern NZ dotterel.

What you can do

Use Rodent Detector Cards to locate a trapping site.

Rat control is easily undertaken and using detector cards prior to installing your A24 is a great way to find the best locations to trap. A couple of A24's around the home and

Goodnature A24 Rat and Stoat trap.

garage will provide continued suppression of rats and mice - remember to add a little pre-feed regularly to have the best effect.

Mice

Summary & Description

Species: Mus musculus
Origin: Europe via Australia
Breeding Cycle:
Diet: Omnivorous
Home Range (ha): Average 0.6
Average Length (mm): without tail, max 115
Average Weight (g): 15 - 20

Mice are small, nocturnal mammals that arrived in New Zealand on Ruapuke Island accidently with the grounding of the flax ship, the Henrietta in 1824. So foreign to the locals, they became known as Henriettas. Mice are well established across New Zealand but not on Stewart Island.

Biology & Ecology

Mouse skull.

Mice tend to avoid animals larger than themselves and rely heavily on their sense of smell and hearing to avoid predators. They tend to reach greatest densities in thick ground cover. The mouse diet of invertebrates and plants is seasonal.

Mice poo is 3.9-7.6 mm long. Singular.

Mice are found throughout New Zealand, and are a significant threat to wrens in alpine regions in Fiordland but can be found in bush, pasture, farms and urban settings.

Threat & Impact

Mouse on a birds nest.

Petrel eggs are eaten by mice.

What you can do

Trapping at 25 m intervals is needed.

The most difficult part of mouse control is the small home range they occupy. To control mice across the landscape, a network with traps set at 25 m intervals is needed. Around the home, a couple of traps

Goodnature A24 Rat & Stoat trap.

will keep control of the little fellas coming inside at the start of the colder seasons. Keep their numbers low in summer and they are less likely to be a bother by winter.

Stoat

Summary & Description

Species: Mustela erminea
Origin: Eurasia & North America
Breeding Cycle:
Diet: Carnivore
Home Range (ha): 60 - 200
Average Length (mm): 256 - 284
Average Weight (g): Male: 324, female: 207

Stoats were introduced to New Zealand with ferrets and weasels in the mid 1870's to control rabbits, which had become major agricultural pests. They had legal protection until 1936, by the time it was removed they were abundant on the North and South Island. They are still absent from Stewart Island. Stoats are distinguished from other mustelid by the black tip on their tail.

Biology & Ecology

Stoat skull.

Stoats have high metabolisms and a heart rate of up to 300BPM. They commonly raid nests while adults are absent and cache the kill in their den to consume over time. They are capable of carrying animals 10 times their own weight. Typically, all females of a litter are impregnated before dispersal meaning

Stoat poo is 40-80 mm with twist on ends.

90% of all females stoats are pregnant from December to September when they are likely to have a litter of 6-8 kits. The ability to delay impregnation is specific to stoats. Stoats are active day and night and are remarkable swimmers, capable of swimming 1.5 km.

Threat & Impact

A penguin killed by a stoat.

Mohua eggs are consumed by stoats.

What you can do

Community groups target species such as the stoat.

Because of a stoat's large home range, a good network is important to keep the population low. By placing traps at 100 m intervals on tracks up to 600 m apart, you can effectively maintain low stoat

Goodnature A24 Rat & Stoat trap.

densities for sustained periods. Goodnature's A24 has passed the National Animal Welfare Advisory Committee's standards for humanness and is one of the best ways to control stoats.

Weasel

Summary & Description

Species: Mustela nivalis vulgaris
Origin: West & Central Europe
Breeding Cycle:
Diet: Carnivore
Home Range (ha): Male: (5-25), female (1-10)
Average Length (mm): 182 - 217
Average Weight (g): Male: 128.8, female: 57.5

Weasels were imported with stoats and ferrets to control rabbits in the 1870's. The weasel has the distinction of being the smallest carnivore in the world and can be identified apart from stoats by their white tummy, small size and lack of black tip on the end of their short tails.

Biology & Ecology

Weasel Skull

During the months between September and March, weasels can have up to three litters of 4-5 kits. If there is an abundance of food, weasels can breed in the year of their birth. They are opportunistic feeders eating insects, lizards, mice and small birds.

Droppings 30-60 mm in length. Twist at each end.

Mice are their most common food source. Populations of weasels can be found throughout the country (with the exception of Stewart Island) but are far less common than stoats or ferrets.

Threat & Impact

A weasel scavenging a birds egg.

Tui eggs are consumed by weasels.

What you can do

Simple trapping networks can be very effective.

Because the weasel has a relatively small home range, you can maintain the population to low levels with a simple network of traps. A well-placed A24 will

Goodnature A24 Rat & Stoat Trap.

keep populations to low numbers. Use detector cards prior to installing your A24 as a great way to find the best locations to trap.

We care about our native wildlife, please be considerate of hedgehogs and other native species when using traps. Dismiss