Norway Rat
Scientific name: Rattus norvegicus
Biology and Life Cycle
The Norway rat, also known as the brown rat because of its bristly brown fur, is the largest among the other rodent pests, averaging 40 cm in total length (including its tail). It weighs about 400- 500 grams, and the males are generally larger than the females. It has a blunt nose, small eyes, small bald ears, and a tail shorter than its body length. It is capable of burrowing, running, jumping, and swimming, but is a poor climber due to its large size and is usually found on lower floors of buildings.
The Norway rat reaches sexual maturity at 3-4 months and it can breed throughout the whole year in a favourable environment. The female can produce 5-6 litters per year, with 8-10 young per litter. The gestation period only takes about 22 days. The Norway rat can live for about a year.
Behaviour
The Norway rat is the most widespread and the most economically damaging rodent pest in Australia. They are often found outdoors in fields, sewers, garbage piles, and drains, but will typically enter buildings and structures in cold winter months when food sources become unavailable outdoors. They can fit through a hole the size of a dollar coin (about 25 mm in diameter), easily entering buildings and structures. When indoors, they usually nest in lower floors, basements, attics, roofs, and inside ceiling voids. Norway rats are nocturnal and forage at night; they eat several times at night and in the daytime. They are opportunistic eaters and will eat anything, but they have a preference for meat, fish, and oats. They hoard their food and consume it in concealed areas. They require a stable water source, aside from the liquid they get from their food. Once they find a stable food and water source, they will repeatedly come back to it. They travel about 40-50 meters away from their shelter to gather food and rarely travel more than 90 meters.
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