Roof rats (Rattus rattus) are also known as ship rats or black rats. They are native to Asia, but have been spread throughout much of the world through human activity and are common along most of the west coast of the United States.
Roof rats may have fur ranging from black to light gray or brown, and have a long, bare tail that is at least as long as their body. Their bodies have a slender appearance compared to Norway rats, and their ears are slightly larger. It may be very difficult to distinguish roof rats from other rodent species, particularly Norway rats, based on appearance alone.
Roof rats may travel up do a few hundred feet while foraging, and will often be seen foraging on properties adjacent to their nests. Roof rats will eat almost anything, including fruits, berries, and vegetation from lawns and gardens, bird and animal feed, pet waste, and garbage. However, roof rats are neophobic, or wary of new experiences. They will avoid unfamiliar foods or objects, including traps.
A female roof rat may produce up to 40 offspring per year, and young roof rats are able to reproduce at around 3 months of age. Because of their high reproductive rate, a few rats can quickly turn into a large infestation if there is adequate food and shelter available. In residential areas, there may be many rats in a small area.
Roof rats, as their name implies, prefer to live above ground. They often enter structures through openings in roofs or under eaves, and can be seen traveling along the tops of fences or power lines or through trees. They often nest in attics or in trees. Roof rats are usually found in close proximity to humans, but may also be found in adjacent areas such as creeks and vacant lots, particularly where there is ample vegetation and water.
Roof rat droppings are pointed and approximately 1/2″ in length.