Rat facts and control tips

The black rat, also known as Rattus rattus, and the brown rat, also known as Rattus norvegicus, are the most common rats. The brown rat, also known as Rattus norvegicus, is the biggest rat in Norway, while the black rat, also known as Rattus rattus, is also commonly found on ships.

Early Māori voyagers came to New Zealand from Norway on ships used for whaling, bringing with them rats. Similarly, early European settlers arrived in New Zealand on ships used for whaling, also bringing rats.

How do rats in New Zealand appear?

Where do rodents reside?

Rats are found on various offshore islands, such as Rakiura/Stewart Island, and certain areas of Fiordland. Rats are skilled climbers.

Norway rats can be found nationwide. They are often seen in or near waterways and are skilled swimmers. They tend not to climb very high.

Brown rats are found all over the country and are skilled climbers.

Norway rats, also known as ship rats, are known to enter structures through the messy and foul-smelling areas such as floors under burrows and the foundations of buildings. They can make their way into homes through holes in roofs and ceilings, as well as cracks in walls. These rats can be found near waterways and are known to live close to humans, just like ship rats.

Rats are omnivores and have a varied diet. They eat eggs and chicks of birds, and they can climb trees. Rats are also good swimmers and prey on ground-nesting birds, while Norway rats are known for their ability to swim.

They are not mean or seen on your property because they are afraid of new situations or foods – they are neophobic, which includes being afraid of new situations or foods, such as ship rats and Norway rats.

What effect do rats have?

Controlling the reproduction of challenging populations, rats also breed rapidly. Rats are consumed by various creatures such as plants, seeds, fruits, flowers, bats, birds, tuatara, lizards, frogs, snails, insects, and other wētā. Due to their omnivorous nature, rats compete for local wildlife’s food and pose a significant threat to New Zealand’s fauna and flora. All three types of rats are a major concern.

The eradication of South Island snipe, New Zealand little bittern, laughing owl, huia, and bush wren, along with the extinction of numerous native bird species in New Zealand, has been primarily caused by the predation of ship rats. The ship rat is considered the most significant threat to wildlife due to its ability to reach trees and climb well, making it a major predator of nests.

Because of their connection to ancestral journeys, kiore also hold cultural and spiritual significance for certain iwi. Flightless invertebrates like wētā are negatively affected by kiore, while small birds are targeted by Norway rats. Even adult nesting albatrosses can fall victim to Norway rat attacks due to their large size. New Zealand dotterels and shore plover, along with their eggs and chicks, are hunted by Norway rats. These rats are known to prey on crabs and mussels and will even plunge into waterways to escape predators. They are most commonly found near bodies of water, but their presence is nationwide.

How to eliminate rodents

In order to effectively manage rats on your property, you need to begin considering other factors such as removing their nesting grounds and food sources as a means of prevention.

  • Did you know that mice can live behind the refrigerator in the kitchen cupboard or any cupboard with hot water? Clean up your home, including basements, spare rooms, cupboards, and get rid of junk like rags, boxes, magazines, and old newspapers to prevent mice and rats from living inside.
  • Make sure to tidy up the outside of your property, as there are sections with overgrown parts, piles of rubbish, appliances or derelict cars, rubble, timber, bricks, and even mice and rats.
  • Make sure to also protect your compost bin from rodents.
  • Avoid leaving bird or pet food outside overnight where rats can reach it.
  • Attempt to close off all entrances to structures and maintain open spaces around residences and buildings.
  • When trees near your house are trimmed, it becomes more likely for it to be easily accessible and infested by rats.
  • Afterwards, after identifying the presence of rats, it is advisable to acquire chew cards and/or tracking tunnels to determine the presence and location of rats on your premises. Employing traps and lures can also effectively manage rat populations.

  • Buy a trap that is endorsed for animal well-being, like the Victor Professional Rat Trap or T-Rex Trap (contained within a tunnel).
  • Monitor every 2-3 weeks, and subsequently inspect the traps on a daily basis until you observe positive outcomes and notice a decline in the rate of captures. If you are not achieving desired results, consider attempting a different location. Position the traps on a level surface in proximity to walls, compost areas, or areas providing shelter. Install 2-3 traps in each backyard and position them within rat tunnels to ensure the safety of children and pets.
  • The capture rate decreases until the second and third week, specifically in areas where there is a large number of check rats. These areas are closer, around 100×50m apart, with lines set up 100m apart. If you are in the bush, you can find them.
  • Serve some peanut butter and frequently refresh.
  • Ensure that you consistently wear gloves when managing your trap or catches.
  • Keep track of your outcomes to determine if your strategy for managing rats is effective. Experiment with alternative approaches if you’re not achieving any results. This may involve relocating your traps to a different area, attempting a different lure like chocolate, or verifying that the trap is properly positioned.