Norway Rats (Brown Rats)
The Norway rat, Rattus norvegicus, also known as the brown rat, common rat, street rat, sewer rat, wharf rat, or the Norwegian rat is greyish-brown in colour but this varies from pure grey to pure black or any combination of this. They are large and stocky,
They have a blunt nose, small close-set ears and a long naked tail. They weigh up to 650g. The rat dropping is 19mm long and oblong shaped.
Thought to have originated in northern China, this rodent has now spread to all continents except Antarctica, and is the dominant rat in Europe and much of North America—making it by at least this particular definition the most "successful" mammal on the planet after humans.
Colour: Grey, Brown or Black
Shape: Short muzzle and a heavy body, with a tail shorter than the combined length of the body and head
Size: Head and body measure 20-27cm (30-45 cm in length including the tail).
Region: Throughout Australia
The Norway rat eats meat, fish, flour, seeds, grains, fruits, vegetables and anything a human will eat. They eat 30g of food and drink about 15ml of water each day. A rat must have water daily to survive.
Norway Rats are capable of mating at 12 weeks old. Females come into heat every 4 or 5 days and have an average of 3 - 7 litters per year (gestation taking 21-24 days) with 6 - 12 pups per litter. Their eyes open at 6 days, are fully furred by 15 days and will be fully weaned at 3-4 weeks. After giving birth the female goes back into heat in 24 hours. Adults live for approximately one year. They have acute hearing, are sensitive to ultrasound, and possess a very highly developed olfactory sense.
The Norway Rat generally lives in outdoor burrows, with a typical burrow having multiple entry and exit points dug under the floors of houses, sheds or other buildings, in banks, in piles of rubble or in rubbish heaps, compost heaps or refuse tips. They live in small, hierarchical family groups, including one or more dominant male. The dominant males territory extends up to about 100m and is explored daily, any intruders being ejected often after a fierce, sometimes fatal fight. They are neo-phobic (showing a fear of new objects), which makes them cautious, and any new object in their territory takes them several days before they will accept it. Normally the rats stay in their burrows during the day and come out a night to search for food.
Rats can squeeze through a hole of 13mm diameter. Though not good climbers because of their bulk, the Norway rat can climb up the inside and outside of pipes and jump as much as a metre vertically, drop 15m without injury and can burrow down to a depth of 1.2m.
Similar to other rodents, Norway rats may carry a number of diseases. They also pose a threat to stored goods like food, with an estimated 12-14% of global food production lost to rodent activity. Damage to buildings is also of major concern, with rodents being able to chew through concrete and metal shuttering in extreme cases. They commonly gnaw through electrical cables bringing a risk of shock or fire as a result.
Poor sanitation and the presence of rubbish allow rats to exist in residential areas. Good sanitation will effectively limit the number of rats that can survive in and around the home. This involves good housekeeping, proper storage and handling of food materials and refuse and elimination of rodent harbourage (shelter). Outside dog kennels should be properly maintained, to reduce potential rat problems.
On farms where food grains are handled and stored, or where livestock are housed and fed, it is difficult to remove all food that rats can eat. In such situations, paying particular attention to removing shelter that rats can use for hiding, resting, and nesting is valuable in reducing rat numbers.
Warehouses, grain mills, and silos are especially vulnerable to rodent infestation. Bulk foods should be stored in rodent proof buildings, rooms or containers whenever possible. Stack sacks of food on pallets with space left around and under stored articles to allow inspection for signs of rats. Good sanitary practices will not eliminate rats under all conditions, but will make the environment less suitable for them to thrive.
Surekil Pest Control use integrated pest management for the control of rodents. The most successful and permanent form of rat control is to make their access to structures impossible. Other options include traps and Rodenticides.