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Pacific rat

Believed to be native to South-East Asia, the Pacific rat is a brownish rodent similar to, but smaller than, the black rat.

The Pacific rat is a pest on numerous Pacific islands, where it damages crops including bananas, sugar cane and mangoes. It also poses a threat to some native plants and animals, especially ground-nesting sea birds. Globally, the Pacific rat has less impact than the black and Norwegian rats (which are established in Australia), but still has significant impacts in certain areas.

While it is currently absent from Queensland, the Pacific rat has the potential to become a widespread and abundant pest here.

Pacific rat is not a prohibited or restricted invasive animal under the Biosecurity Act 2014.

Scientific name

Rattus exulans

Other names

  • Polynesian rat, Maori rat, kiore

Similar species

  • Common black rat

Description

  • Rodent similar in appearance to common black rat but slightly smaller, with body generally 80–140mm long, tail 108–147mm long, weight around 30–180g.
  • Fur is brown to grey-brown with spiny black guard hairs.

Habitat

  • Prefers disturbed habitats associated with towns, villages and farms, often where there is suitable ground cover to protect it from predators.

Distribution

  • Currently absent from Queensland but could survive and spread over substantial areas if released in sufficient numbers.

Life cycle

  • Breeding occurs throughout year, with peak October–June.
  • Possible to have 1–6 litters per year, but commonly 3–4.
  • Gestation 21–24 days.
  • Can live up to 1 year in wild.

Crops affected

  • Numerous, including bananas, sugar cane and mangoes.

Affected animals

  • Sea birds
  • lizards

Impacts

Economic

  • Damages range of crops.

Environmental

  • Significantly affects ground-nesting birds, insects and small lizards.
  • Can also affect some tree species by eating plant parts, seeds and seedlings.

Social

  • Can enter homes, eat food, bite people.

Control

  • Coordinated baiting and trapping programs are effective.

Legal requirements

  • The Pacific rat is not a prohibited or restricted invasive animal under the Biosecurity Act 2014. However, by law, everyone has a general biosecurity obligation (GBO) to take reasonable and practical steps to minimise the risks associated with invasive plants and animals under their control.
  • Local governments must have a biosecurity plan that covers invasive plants and animals in their area. This plan may include actions to be taken on certain species. Some of these actions may be required under local laws. Contact your local government for more information.
  • It is considered a non-indigenous species and it is an offence to release or cause them to be released into the wild.

Further information