What are brown rats?
They are rodents, brownish/grey on the back and grey underneath. Their average weight is 335g and they are 300-450mm long. They are also known as the common rat, sewer rat and Norway rat. Like all rats, they are nocturnal, although they are sometimes seen during the day. They must continually gnaw to wear down their teeth. They are active burrowers, good climbers and reasonably good swimmers (often leading to confusion with water voles). They have poor eyesight and are colour blind but they have a good sense of smell and taste and acute hearing. Rats are capable of reproducing at 3-4 months old, and can have 3–6 litters per year, depending upon food availability and harbourage. The litter size can be around 6–11 young, with a lifespan of between 12–19 months. Some estimates give 5 rats for every human being on the earth and that, wherever you are, there is a rat within 15 metres.
