Rattus norvegicus

Medium sized rodent distinguished from mice by their larger size and long tail. Their bodies usually measure around 12cms. Their average life span is 2-3 years. Known as Old or true rats they originated in Asia. The common species are opportunistic survivors and often live with and near humans. Known to have carried the Black death through their fleas their reputation for being disease ridden and dirty preceeds them. Rats are omnivorous, aggressive, intelligent and extremely adaptable. Females produce as many as 8 litters each year with as many as 20 young per litter. The gestation period is three weeks, and the young reach sexual maturity in about two months.