This introduced mouse is usually nocturnal, commonly seen around buildings or under garden fixtures. Tail is about 8 cm long.
Rats are found everywhere on earth where man is. They are one of the most adaptable animals that are alive today, and the most intelligent of the rodents. Rats are able to discern different human personalities and a pet white rat (which is the same species as a wild rat) easily learns the difference between it's regular handler and a stranger.
The black rat (Rattus rattus) (alt. ship rat, roof rat, house rat, Alexandrine rat, old English rat) is a common long-tailed rodent of the genus Rattus (rats) in the subfamily Murinae (murine rodents). The species originated in tropical Asia and spread through the Near East in Roman times before reaching Europe by the 6th century AD and spreading with Europeans across the world. Today it is again largely confined to warmer areas, having been supplanted by the brown rat (Rattus norvegicus) in cooler regions.
Despite its name, the black rat exhibits several colour forms. It is usually black to light brown in colour with a lighter underside. In the 1920s in England, several colour variations were bred and shown alongside domesticated brown rats. This included an unusual green tinted variety. Today, very few people today keep black rats as pets. Most pet rats (or fancy rats) are domesticated brown rats.
A typical black rat will be 15–20 cm (5.9–7.9 in) long with a further 20 cm (7.9 in) of tail. It is nocturnal and omnivorous, with a preference for grains and fruit. Compared to the brown rat, it is a poor swimmer, but more agile and a better climber, tending even to flee upwards. In a suitable environment it will breed throughout the year, with a female producing three to six litters of up to ten young.
Females may regulate their production of offspring during times when food is scarce, throwing as few as only one litter a year. R. rattus lives for about 2–3 years. Social groups of up to sixty can be formed.
The Norway rat are the predominant species around the world.
Norway rats are husky, brownish rodents that weigh about 11 ounces. They are about 13 to 18 inches long including the 6 to 8 1/2 inch tail. Their fur is coarse and mostly brown with scattered black on the upper surfaces. The underside is typically grey to yellowish-white.
Rats will eat nearly any type of food, but they prefer high-quality foods such as meat and fresh grain. Rats require 1/2 to 1 fluid ounce of water daily when feeding on dry food. Rats have keen taste, hearing and sense of smell. They will climb to find food or shelter, and they can gain entrance to a building through any opening larger than 1/2 inch across.
Rats have litters of 6 to 12 young, which are born 21 to 23 days after mating. Young rats reach reproductive maturity in about three months. Breeding is most active in spring and fall. The average female has four to six litters per year. Rats can live for up to 18 months, but most die before they are one year old