Family: Rodent

Genus: Rattus

Species: rattus

Threats/Control Methods – Regional

The Roof Rat can be a threat to human health. This species has been identified as a potential carrier of diseases that can affect humans, such as Hantaan virus (Haemorrhagic fever), Murine typhus (Rickettsia typhus), Leptospirosis, Rat bite fever (Spirillium minor) and the Plague (Yersinia pestis). The potential health impacts of this species are currently being researched at the CSIRO.

Threats/Control Methods – Local

These Rats can be difficult to control because if the mother rat has become wary of chemical deterrents like 'Ratsac' or traps, many of her young will also learn to avoid them.

Local/Urban Actions

There are some indicators that give clues to whether a Roof Rat is inhabiting a residency. Look out for grease smears on vertical surfaces, evidence of gnawing, smell, strange noises at night, disappearing food and strange reactions from your own pets. Rats are difficult to remove from an area relying on common traps and baiting methods alone. Trained pest controllers are the most effective.

Common name/s

Black Rat, Roof Rat.

Distinguishing Features

Body size is about 8cm in length. The upper body colouring is brown, black or charcoal grey, with a cream or white underbelly. The tail is scaly and long relative to its body size. Front teeth are chisel shaped.

Similar Species

The Australian native Bush Rat (Rattus fuscipes ) and the Agile Antechinus (Antechinus agilis ).

Distribution

This species is found widely across Australia, especially in coastal regions & human modified areas. It is also found commonly in and around human settlements where food and shelter is readily available in most countries of the world.

Country of Origin

Europe

Associated vegetation community

In their natural environment Roof Rats are common to woodlands, forests and grasslands. They are typically associated with human settlements, including cities, rural villages and farms.

Limiting Resources

Roof Rats are very adaptable and can live in a variety of places such as roofs, cavity walls, trees, scrapes or burrows around farms. A close distance to humans usually ensures the food and water requirements of this species are met.

Breeding

A mature female rat can give birth to about 20 young in a year (4 to 6 at a time). Young are born in nests made from paper, rubbish, plastics, grass or other material. They become completely independent and able to reproduce after three months. Outdoor populations in the natural environment tend to peak in summer or early autumn, while indoor populations remain constant throughout the year.

Behaviour

Roof Rats are very good swimmers and climbers, meaning they can access most areas to feed, shelter and breed. Usually they move about 50m from their nest site. They will climb trees to steal eggs out of birds' nests or to eat fruit. They are known to cause trouble by gnawing at pipes and electrical cords. Rats have very poor vision, relying on their keen sense of smell, acute hearing and their whiskers and sense of touch. They spend time around water bodies and beaches and are the most commonly seen rodent in public parks and beaches.

Food Species

In the wild, Roof Rats will eat a range of fresh plant material, nuts and seeds, fruit and vegetables and tree bark. In human environments they are known to eat almost anything.

Predators

Feral or domestic Cats, Dogs, snakes, birds of prey, and other rats will all attack and kill Roof Rats.

Interesting Fact

If the mother rat has become wary of rodenticide or traps, many of her young will learn to avoid them. This learning experience can make management difficult in sites where long-term rodent suppression programs have been unsuccessful in the past.