The most common of the rat species are the brown and black rat. Most of the North American rats are opportunistic and live near humans and agricultural areas . Rats are typically distinguished from mice by their size.
These rodents can carry zoonotic (infectious diseases which can be passed to humans) diseases including leptospira, toxoplasma gondii, campylobacter, and historically were believed to be the carrier of the Black Death in Europe during the Middle Ages.
Rats are omnivorous eating grain, insects, fish and meat. Most rats are nocturnal. A brown rat can produce up to 2,000 offspring in a 12 month period. Rats are communal and will live together in packs.
Rats will mark their territory with urine, leaving an odor.