Rattus

Rattus is a genus of rodents in the family Muridae, subfamily Murinae, comprising more than 50 species of rats native to Asia and the Pacific, with many species subsequently introduced worldwide where they often become pests. The two best-known species are Rattus norvegicus, commonly called the brown rat or Norway rat, and Rattus rattus, the black rat. Other notable members include the Asian house rat (Rattus tanezumi) and the Polynesian rat (Rattus exulans).

Description and ecology: Rattus species are medium to large rodents with long tails, strong incisors, and well-developed forelimbs. They are generally highly adaptable, occupying urban, agricultural, and natural habitats. Most species are nocturnal and social, living in shelters and traveling in groups. Diets are omnivorous, including grains, fruits, invertebrates, and human food waste.

Reproduction and life history: They reproduce rapidly, with females giving multiple litters per year when conditions are favorable. Gestation and weaning periods are short relative to body size, allowing population growth to accelerate under suitable conditions.

Ecological and economic significance: Rattus species are among the most widespread mammalian pests. They cause crop damage and contaminate food stores, and require control in homes, farms, and seaports. They are vectors for a range of pathogens, including leptospira bacteria and, historically, fleas carried by rats played a central role in plague transmission.

Taxonomy note: The genus Rattus is part of the tribe Rattini within the subfamily Murinae. The taxonomy of the group has been revised as new species are described and genetic analyses refine relationships among species.