The brown rat is also known as common rat, street rat, sewer rat and Norway rat. The brown rat is one of the largest rodent, with a head and body length up to 11 inches long. It heights between 140 and 500 grams. The brown rat usually lives wherever humans live, particularly in urban areas. Their fur is usually brown or dark grey. The Brown rat is a nocturnal creature and also it's a good swimmer and climber. They can also dig well. An interesting fact is that the brown rat can produce different types of ultrasonic cries. They can consume everything, but cereals and grains are a substantial part of their diet. One of their favourite foods can also be scrambled eggs, mac and cheese and raw carrots and the least favourite foods are peaches and celery. A female can produce up to 5 litters per year and as a matter of fact, the female can get pregnant immediately after giving birth and can nurse one litter while pregnant with another. When the food is restricted they can extend their pregnancy by over two weeks. Rast, like most mammals, also form family groups. However, rats are territorial animals and can act aggressively.