This is a rat scientifically known as Rattus rattus and is the type of rat that was responsible for the plague during the middle ages. It is also known as the ship rat as in the past these rats were common on sailing ships.
It has three subspecies each with different coloring hence color cannot be used to identify it. Based on the sub species it can be black with a grey belly, brownish with streaks of grey or agouti with a white stomach. There is also the issue of crossbreeding in certain areas, which makes for a mixture of colors.
Aside from color it is typically 13 to 18 inches in length. The tail is a distinguishing characteristic as it is longer than the rest of its body. It has large ears and is slender with a sleek appearance. It is quite agile and can easily climb walls, and get through small openings, to get from place to place. Their nests can be found in high places such as attics and trees and the top floors of buildings.
They are essentially omnivorous, however, when outdoors they prefer to eat fruits and nuts if available. They also eat insects, human food, pet food, and non food staff such as clothes and paper.
The female can lay as much as four litters a year with each litter containing 5 – 8 young. The young are born after an average of three weeks from conception, and they grow rapidly and are capable of reproducing after three months.