Roof rats are also called black rats, ship rats, or house rats.
Roof rats (Rattus rattus) are black to light gray or brown with a lighter underside. Their bodies are 5-7 inches long, with a long (6-9 inches long), hairless tail that is as long or longer than their body. They are more slender and have larger ears than Norway rats. It may be very difficult to distinguish roof rats from other rodent species, particularly Norway rats, based on appearance alone.
Roof rats are omnivores and may travel hundreds of feet to forage on almost anything – including fruit, nuts, pits, seeds, bird and animal feed, pet waste, and garbage. Roof rats are neophobic (afraid of new things), and it is believed that they learn which foods are safe to eat from watching their parents and nest mates.
Roof rats prefer to live above ground and are considered semi-arboreal (tree-living). They often enter structures through openings in roofs or under eaves, and can be seen traveling along the tops of fences, power lines, or through trees. They often nest in attics or in trees but can be found in any part of the house including the crawl space underneath. Their gnawing may also cause substantial damage to house wiring and insulation. Roof rats require close proximity to humans, but may nest adjacent to buildings in areas with dense vegetation and water.
A female roof rat typically has 5 litters per year with 5-10 pups in each litter. Young roof rats are able to reproduce when about 9 weeks old. Maximum lifespan is about two years but they usually do not survive more than one year in the wild.
Roof rats may carry many different bacteria and parasites, such as those that cause typhus, Weil’s disease, rat bite fever, toxoplasmosis, and trichinosis.
Roof rats are native to Asia but adapted to live with humans very early on and have traveled extensively with us in our vehicles through trade, immigration, and the transport of goods.
Page last reviewed: November 8, 2023