By most standards, rats are considered pests or vermin. They are very destructive to crops and property. The most common and successful species of rat found in Britain is the brown rat. The black rat can also be found, however it is one of the rarest mammals in Britain. Due to their opportunistic nature, brown rats are found all over Britain from farms to towns. Rats have a significant impact on food production. Estimates vary, but it is likely that about one fifth of the world’s total food output is eaten, spoiled or destroyed by rats.
Rats are distinguished from mice by their size; rats generally have bodies longer than 12 cm (5 inches). They will quickly overpopulate when they live in a place where they have no predators, such as in cities and their numbers can become hard to contain. They also can carry over thirty different diseases dangerous to humans, including Weil’s Disease, Typhus, Salmonella and Bubonic Plague.