Despite being home to dozens of rodent species, the state of Washington has no true native rats. It does, however, have two species of introduced rat and several native critters commonly referred to as rats -- although technically they aren’t -- including the kangaroo rat, woodrat and muskrat.
Black rats (Rattus rattus), also known as ship rats, roof rats, house rats and fruit rats, have accompanied humans around the globe, although they aren’t usually very welcome. This rat originated in India and is now found almost everywhere, although the Norwegian rat predominates in most of North America. Black rats are excellent climbers and are often found around orchards, earning them their alternative name of fruit rats.
The Norwegian rat (Rattus norvegicus) is another species associated with humans and originally came from Eurasia, specifically Siberia and China. Pet rats belong to this species, as do most of the wild ones viewed as pests in the U.S. In Washington, the species is as widespread as it is elsewhere in North America, often living in extremely close proximity to humans. If you see a rat in your kitchen, he’s probably Norwegian.
Ord’s Kangaroo Rat
The gerbil-like kangaroo rats resemble true rats only in terms of their size; they are not at all closely related. In Washington their family -- Heteromyidae -- is represented by Ord’s kangaroo rat (Dipodomys ordii) and the smaller great basin pocket mouse (Parognathus parvus). Ord’s kangaroo rat is a desert animal, well adapted to dry conditions and mostly solitary outside the breeding season.
The muskrat (Ondatra zibethicus) is another Washington rodent only superficially similar to rats, belonging to the vole and lemming family (Cricetidae), rather than mice and rats. In direct contrast to the Norwegian and black rats, the muskrat is native to Washington but appears as an introduced species in other parts of the world, including large areas of Europe. Muskrats prefer wet habitats, living in and around lakes, rivers and streams, where they create complex burrow systems in the banks.
The bushy-tailed woodrat (Neotoma cinerea) is another member of the family Cricetidae. As the name suggests, the species inhabits woodlands but is also quite happy in desert and scrubland. The main thing that bushy-tailed woodrats appear to look for in a home is a stony aspect, nesting in cliffs, rocky outcrops, caves and even abandoned mine shafts.
- Burke Museum: Mammals of Washington -- Rodentia
- Animal Diversity Web: Rattus rattus -- House Rat
- The IUCN Red List of Threatened Species: Rattus norvegicus
- Animal Diversity Web: Dipodomys ordii -- Ord's Kangaroo Rat
- The IUCN Red List of Threatened Species: Ondatra zibethicus
- Animal Diversity Web: Neotoma cinerea -- Bushy-Tailed Woodrat
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