Rats and mice are well adapted to living in close association with humans and are a risk to the health of the community. Their presence is undesirable due to their ability to physically damage structures and furnishings, spoil and contaminate food causing food poisoning and transmit diseases to humans including the plague, dysentery, leptospirosis and typhus fever. Gnawing causes damage to a variety of materials and objects including electrical wires which have been known to cause fires.
They may live and nest within buildings indefinitely, provided they have access to food and water. Being creatures of habit, they will travel the same routes to water and food sources, assisting in control with baiting programs and trapping.
There are three main species of introduced rats and mice that are considered pests:
- The Roof Rat (Rattus Rattus): Black or grey in colour with large ears and eyes, and pointed nose. Heavy set body that is shorter than the tail. An excellent climber and jumper that prefers nesting in roof cavities. Can also be found in trees including palm trees. Eats grains, nuts, fruits and seeds in vegetables.
- Norway Rat (Rattus Norvegicus): Thick set, brown or grey in colour with small ears and eyes and a blunt nose. Heavy set body is longer than the tail. Usually lives in ground burrows, also found in sewers and rubbish dumps. Prefers eating grain/cereal products, however it will eat almost anything.
- The House Mouse (Mus musculus): A small-sized brownish-grey above, white to grey or pale yellow below. Bulging eyes in a small head with large rounded ears. Soft dense fur to 7mm long with scaly tail, about same length as body 75-100 mm.60-100 mm in size. Can be found where there is shelter, warmth, food and nesting materials. Prefers to eat grains, nuts, fruits and seeds in vegetables.