The most common pet rat is a descendant of the brown rat (Rattus Norvegicus), which spread over to Britain from Asia via the shipping traffic in the 18th Century, largely replacing the black rat (Rattus rattus).
Rats have lived close to human habituation for centuries, long before the beginning of recorded history. They were originally domesticated in the early 1800s for use in ratting contests with terriers. This cruel practice, fortunately now abolished, involved a time limit whereby the dog had to kill as many rats as possible. Rats were also used in scientific laboratories in the late 18th Century.
Rats live for an average of three years. Distribution and Habitat in the wild Although originally native to East Asia and Japan, brown rats are now distributed world-wide. They are highly adaptable and can be found in a variety of habitats, typically near human habituation.
Behaviour in the wild
Brown rats are typically nocturnal, although they will sometimes forage for food during the day. They live in loose colonies, made up of aggregations of clans - usually consisting of a mated pair, or a male and a harem of females.
They are omnivorous but prefer starch and protein-rich foods, such as cereals. Their diet includes meat, fish, vegetables, weeds, earthworms, crustaceans, nuts and fruit. They sometimes cache food to return to later.
Clans will defend their territory from other rats, and there is a dominance hierarchy whereby the biggest rats are dominant over their smaller counterparts. Home ranges are generally 50 metres in diameter.
Rats have well-developed senses of hearing and smell. In areas of high population, fights will often break out, involving a vigorous scuffle leading to the loser being chased off.