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The common pest rat in the UK is the Brown rat (Rattus Norvegicus), the Black Rat (Rattus Rattus) is rarely seen these days and is only usually found in dock areas.

The Brown Rat can measure some 20-25cm in body length and weigh half a kilo, its tail can be a further 15-20cm. It is omnivorous and needs to eat about 50g of food daily. Rats, unlike mice, need to drink so will be found near a source of water, their daily liquid requirement is approximately 20ml.

As rats are rodents their teeth are constantly growing and they need to gnaw, rats teeth are incredibly strong and they are capable of gnawing through a variety of materials including glass, wood, lead and plastic with little difficulty.

Their lifespan is about 9-18 months and they can produce 7 litters a year, each having up to 10 babies per litter. The females are pregnant for about 21 days and the young weaned after 3 weeks. They are sexually mature at around 12 weeks of age.
Rats are very good swimmers and are very agile, though the Brown Rat is slightly less agile than the Black Rat. They can climb well and can jump vertically up to a metre, they can squeeze through a gap of only 15mm.

Their senses are well adapted for survival and they have excellent hearing, although their eyesight is poor beyond close range, they can easily detect movement up to around 15m.

Rats sense of smell is exceptional and they use scent trails to navigate their surroundings, they will mark paths leading to food sources, harbourage etc. Smell is also used when they meet other rats and they can detect members of their own colony from other rats.

Touch is also a very important sense to rats and they use the whiskers and hairs on their bodies to navigate and explore their surroundings.

Rats are cautious of new objects and will avoid anything it is unsure of, this is known as neophobia and can last for several weeks.