NORWAY RAT (Rattus norvegicus)
A large, burrowing rat, weighing up to 700gm but usually in the range 350 – 450gm and on average about 25cm in head-body length. The body of the Norway rat is covered in shaggy fur that is brown or gray in colour. The ears and tail are small, the tail being shorter than the head-body length and the muzzle is blunt. Females have 12 teats (vs the Roof rat with 10 and the Polynesian rat with 8).
BEHAVIOUR AND DIET:
The Norway rat is able to live in a wide range of man-made habitats including drains, sewers, farms, domestic houses, warehouses, rubbish tips, restaurants and other terrestrial environments. Norway rats typically nest in underground burrows, from which they enter buildings in search of food. They tend to remain in hiding during the day.
Norway rats are omnivorous and feed on a variety of food sources. If given the choice, they will consume meats, fruits, grains and nuts. They require water to drink and they position their colony as close to a water source as possible. Norway rats live in communities with dominant and subordinate members, though they are not truly social.
Like most rodents, the Norway rat has a high breeding rate and female rats can breed throughout the year, potentially producing average litter sizes of 6 – 10 pups every 4 – 6 weeks.
VISUAL SIGHTINGS – Sightings of live or dead rodents clearly indicate rodent activity. Live sightings, especially during the day, can point to nest disturbance or possibly an infestation, the latter which can sometimes lead rats to forage during the day, when there is less competition for food.
BURROWS / NESTS – Typically found at ground level and outside in the vicinity of buildings and structures. However, are also found in basements of poorly maintained buildings.
GNAWING DAMAGE – Like all rodents they have very strong teeth and can damage almost any material they encounter, including electrical cables and wires, wood, lead and other metals, building construction and household materials.
DROPPINGS – Norway rat droppings are shaped like a capsule, with rounded ends and 18 to 20 cm long.
GREASE SMEARS – Grease marks are produced as the rodent travels along an edge, and oils in their fur are deposited.
DISEASE TRANSMITTERS – Norway rats have been shown to carry a very wide range of diseases that can infect humans and livestock, including leptospirosis, salmomellosis, toxoplasmosis, cryptosporidiosis, rat bite fevers and many additional infections. These diseases are often spread by the faeces and urine with which they contaminate their environment as well as fleas that they usually carry.
ECONOMIC IMPACT – Rodents destroy structures such as walls, floors and doors; electrical wiring; plumbing; fuel lines and furniture. They consume and contaminate food supplies and consumer goods. Insurance companies estimate that approximately 25% of all building fires are caused by rodents gnawing through electrical cables.
Ensure that all points of ingress to buildings are properly sealed – pay particular attention to where utilities are brought in to buildings – adult rats can scramble through holes of less than an inch and juveniles, even less. Where these points of ingress are doors and windows of less than 1.25m off the ground, ensure that they remain shut when not in use and are tight fitting to their architraves. If your building is connected to another, ensure that any adjoining roof spaces are adequately sealed.
Keep foodstuffs tightly contained in metal or glass containers with tight fitting lids.
Keep clutter to a minimum, both inside and outside buildings — less clutter means less places to hide and to build a home.
Outdoor Rubbish – Place outdoor rubbish bags in metal bins with securely fitted lids, to prevent access to the contents.
Solution – Please see our rodent control page for more practical steps you can take to help prevent rodent infestations and also for our own specialist solutions.