The dozens of species of rat (genus Rattus) between them inhabit almost every natural habitat, from isolated tropical islands to forests. They include swamp rats, bush rats, rice field rats and forest rats. Then there are a lot of similar-looking rodents popularly referred to as rats, such as wood rats. However, most people are thinking of one or two species when they talk about rats: black rats and Norwegian rats.
Norwegian Rats - Rattus Norvegicus
Norwegian rats now live almost everywhere that humans do, often in buildings, where they are not always welcome. However, the species has been around for longer than cities and the original habitat of these rats was quite different. Their range was originally limited to parts of Siberia, China and Japan, where the rats inhabited forests. Today, the species has spread with humans all over the world, occupying natural and artificial habitats, such as urban and suburban areas, farmland and woodland, in temperate areas. In tropical regions, Norwegian rats tend to stay in more developed environments, as they are not as well adapted to natural tropical ecosystems.
Black Rats – Rattus Rattus
Black rats were originally the most common rats around humans. They have the dubious distinction of being the species that carried bubonic plague -- the Black Death -- through Europe in the Middle Ages. From the end of the 19th century, Norwegian rats began taking over in most temperate regions as the rat species living in closest proximity to humans. Black rats are still found in these areas, but tend to be more plentiful in agricultural habitats. In some parts of their former range, for example the United Kingdom, they are now endangered. They remain the most common rat in many tropical areas. Like the Norwegian rat, they too originated in Asian woodland, in this case most likely India, and still appear to prefer arboreal habitats -- in the USA the species is often referred to as “fruit rats” because of their abundance in orchards.
Pet Rats - Rattus Norvegicus
Most pet rats are a domesticated variety of Norwegian rats. Because the species is so adaptable and has been living alongside humans for so long, your pets don’t need a habitat that in any way resembles a forest. What they do need, however, is a habitat that satisfies some of their basic needs.
How big and elaborate you make the cage depends in part on how long you can let the rats out each day. The basics are a large cage, a few inches of an absorbent, paper-based bedding and a couple of nest boxes for sleeping. Rats also like the opportunity to climb, making multilayered cages a good option, at least until the rats get older. Basically, the more space and the more things to explore, the better.
No other rat species is so widespread or so common as the Norwegian and black rats. The other rats tend to have specialized habitats and a limited geographical range. An example is the western New Guinea mountain rat (Rattus arrogans), which, as the name suggests, is only found in the mountains of central and western New Guinea. In contrast, the rice field rat (Rattus argentiventer) lives throughout the wet grasslands and rice paddies of Indochina.
None of these species lives in such close contact with humans as the Norwegian and black rats, or has been domesticated. The giant pouched rats (genus Cricetomys), who also appear in the pet trade and occasionally as service animals, mainly in mine detection, aren’t particularly closely related to the true rats.
- Arkive: Brown Rat
- Animal Diversity Web: Rattus Norvegicus -- Brown Rat
- The IUCN Red List of Threatened Species: Rattus Norvegicus
- Arkive: Black Rat
- Animal Diversity Web: Rattus Rattus -- House Rat
- The IUCN Red List of Threatened Species: Rattus Rattus
- The IUCN Red List of Threatened Species: Rattus Arrogans
- The IUCN Red List of Threatened Species: Rattus Argentiventer
Judith Willson has been writing since 2009, specializing in environmental and scientific topics. She has written content for school websites and worked for a Glasgow newspaper. Willson has a Master of Arts in English from the University of Aberdeen, Scotland.