Brown Rat

The Brown Rat generally nests outdoors in burrows 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.

During the day rats usually stay in their burrows and come out a night to search for food.

They eat meats, fish, flour, seeds, grains, fruits, vegetables and anything a human will eat. They eat 30g of food per day and drink about 15ml water each day. A rat must have water daily to survive.

The brown 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, measure 30-45 cm in length including the tail. 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.

Brown rats 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. Like mice, rats are colour blind and have poor eyesight. Their sense of smell and touch is however acute.

Rats can squeeze through a hole of 13mm diameter. Though not good climbers because of their bulk, the brown rat can climb up the inside and outside of pipes and jump as much as a metre vertically, drop 15cms without injury and can burrow down to a depth of 1.2 m.

Life Cycle

Brown rats are capable of mating at three months. Females come into heat every 4 or 5 days. Females have an average of 3 - 7 litters per year with 6 - 12 pups per litter. Their eyes open at 6 days and they are fully furred by 15 days. After giving birth the female goes back into heat in 24 hours. Adults live for approximately one year. Brown rats have 6 pairs of nipples.

Signs of Rats in and around your structure.

• Droppings, which are soft when fresh, along well-travelled pathways, in feeding areas and near the rodent's shelter.
• Tracks, including footprints and tail marks, on dusty surfaces, in mud and snow.
• Urine along travelled paths or in feeding areas. Both wet and dry rodent urine will glow under ultraviolet light (black light).
• Smudge or rub marks on beams, rafters, walls, pipes and other fixtures.
• Gnawing marks on doors or ledges, in corners, in wall material, on stored material or on other surfaces.
• Noises in the walls caused by gnawing, climbing, clawing, squeaks and fighting, particularly at night when rodents are most active.