The Norway rat, also called the brown rat, is not a native part of Arizona’s wildlife. It is an introduced commensal rodent that arrived with human settlement and lives wherever people do, in cities, farms, warehouses, and along canals and riverbanks. It leaves only a faint trace in open wildlife databases: 16 Arizona records, 12 of them from iNaturalist. That scarcity says less about how many rats there are than about where they live, tucked against buildings and storm drains rather than out in the wild country naturalists tend to survey.
An introduced species, not a wild one
Rattus norvegicus is native to the grasslands of northern Asia and spread across the globe as a stowaway on ships. NatureServe flags it as exotic in Arizona and assigns it the rank SNA, Not Applicable, because conservation status is reserved for native populations. The Arizona records concentrate almost entirely in Maricopa and Pima counties, which is to say in and around metropolitan Phoenix and Tucson.
Where it turns up in the state
The brown rat is an animal of the built landscape. It follows food and water into alleys, granaries, sewers, dumps, and the vegetated banks of canals and washes across the Sonoran lowlands. It is not a creature of the desert or the mountains in its own right; it goes where people and their surplus go, and in Arizona that means the low, warm, irrigated cities.
Reading the record
Because the brown rat lives against human structures, its handful of database records track opportunity more than biology. A rat photographed by a wall or a dumpster becomes a data point; the many that never are simply do not. The thin, uneven monthly counts should be read that way, as a footnote to an introduced animal rather than a portrait of a wild one.
Full species profile
