[297] Rattus norvegicus, Rat

[297] Rattus norvegicus, Rat

Introduction

Rattus norvegicus, the Rat, is a very common and very widespread small animal, normally treated as unwanted vermin.

It can be called the Brown Rat, Common Rat, Street Rat, Sewer Rat, Wharf Rat, Parisian Rat, Norway Rat or Norwegian Rat but is usually just called a Rat.

There are hundreds of species called Rats.

Taxonomy

Kingdom – Animals

Phylum – Chordates

Class – Mammals

Order – Rodentia

Suborder – Myomorpha

Superfamily – Muroidea (Mice, Rats, Voles, Hamsters, Gerbils and others)

Family – Muridae (Mice, Rats and Gerbils)

Subfamily – Murinae (Old World Rats and Mice)

Tribe – Rattus

Genus – Rattus

Scientific Name – Rattus norvegicus.

The Fancy Rat and Laboratory Rat may be called Rattus norvegicus domestica. (It is not clear why this has what looks like a feminine ending when the masculine domesticus would match Rattus and norvegicus. It can only be a noun in apposition, domestica meaning housekeeper. See Names.)

Name

The Brown Rat was originally called the Hanover Rat in Eighteenth Century England to associate it with the House of Hanover. It was named Rattus norvegicus in 1769 by the English naturalist John Berkenhout, who believed it had come from Norwegian ships. Its exact origins remained uncertain but it now assumed to have come vie Persia (now Iran) in the early Eighteenth Century.

The word rat comes via Old English from Germanic, Indo-European roots. The Brown Rat was unknown in Northern Europe until fairly recently – so it may have applied to the Black Rat at first.

In mediaeval Latin the word rattus was used for a rat, coming from the Germanic.  (In earlier Classical Latin the word mus meant either a mouse or a rat.)

Rats in general

There are about five or six hundred species in the Murinae subfamily, generally called rats or mice. The long, thin tail is a distinctive feature. There is no taxonomic distinction between rats and mice. Newly discovered species are generally given the name Rat or Mouse depending only on size. Many other less closely related species of rodents are also called rats.

The genus Rattus has at least sixty species but may also be considered to include all the species of about 35 other genera!

Norwegian Rat

The Rat is very much like a larger version of a Mouse. They can be brown or dark grey. I won’t attempt to describe them or how they differ from their relatives.

Over most of the World the Brown Rat is now associated with people and it has spread with people to cover the World. It has largely replaced Rattus rattus, the Black Rat, which spread across Europe about a thousand years earlier.

First sightings in Europe were about 1550, reaching France, Germany and Britain around 1730-50.

The population of rats in the UK is estimated to be a little over the human population.

Habitat and use

Rattus norvegicus was originally native to southeast Siberia, northeast China and parts of Japan but is now found worldwide.

For its use as a Fancy Rat (a show animal or pet) and as a laboratory animal, see [232] Mouse, which has similar variants.

Rats can live in damp environments such as river banks but are often associated with human habitation and sewers.

Other Notes

I don’t think what I am going to say will surprise you but almost all of the rats I have seen have been associated with outdoor areas associated with bird feeders. They can climb up and dislodge things like suet balls and happily scavenge what falls to the ground. It is a pity that sometimes the bird feeders are removed because of the hazard of rats. They are generally treated as vermin – unwanted animals associated with spreading disease and destroying crops.

See also

See [232] Mouse, which also considers Fancy Mice and Laboratory Mice.

[042] the Water Vole is a close relative sometimes called the Water Rat,

[042] Arvicola amphibius, Water Vole

[040] Arvicola amphibius, Water Vole

Introduction

Arvicola amphibius, the Water Vole, is a small, semi-aquatic mammal that used to be common and widespread through Britain but has been declining in numbers for half a century or more.

Strictly speaking it is the European Water Vole or the Northern Water Vole and it is often informally called a water rat – as immortalized in The Wind in the Willows by Kenneth Grahame.

There are two other species of Arvicola called water voles found in Europe and a slightly larger, similar Water Vole in North America.

I was keen to include this species but my stock of pictures is very limited

Taxonomy

Kingdom – Animals

Phylum – Chordates

Class – Mammals

Order – Rodents

Family – Cricetidae (Hamsters, Voles, Lemmings and American Rats and Mice)

Subfamily – Arvicolinae (Voles and others)

Genus – Arvicola

Scientific Name – Arvicola amphibius

The placing of Arvicolinae within Cricetidae is disputed. Some authorities put them under Muridae in common with European rats and mice.

Linnaeus

Modern scientific Taxonomy owes its origin to Carl von Linné (1707-78) usually known by his Latin name, Linnaeus. (In those days Latin was the universal language of science and education.) He defined the system and gave many species the scientific names that we still use today.

He didn’t get everything right and he defined two species of water vole in the same work on the same page. Arvicola terrestris and A amphibius are now recognized as the same species. It used to be called A terrestris but the first person to resolve the ambiguity picked A amphibius, which has now become its official name.

(Somehow it also has the obsolete synonyms Mus amphibius and Mus terrestris, also both attributed to Linnaeus. Perhaps he thought they were mice before he separated them into Arvicola.)

Name

Vole is an Orkney (from Norse) dialect word for a mouse. Before about 1800 all voles were called mice.

Arvicola, from Latin roots, means ‘Field inhabitant,’ but of course voles used to be called field mice and they still are in some countries.

Description

The technical definition of voles depends mostly on the structure of their molar teeth.

They in some ways similar to rats but they have rounder noses, deep brown fur, chubby faces, short fuzzy ears and hairy paws and tail.

Habitat

They live in riverside burrows and prefer calm, slow moving water. In Britain their habitat is declining and there are some attempts to try to reintroduce them.

In places such as central France they live in large numbers and cause excessive damage to crops.

Other Notes

The only place I have ever seen this animal is at the WWT Slimbridge site. They are more likely to be out in the sun.

I have to mention The Wind in the Willows, a novel written for children, based around four anthropomorphised animals called Mole, Rat, Toad and Badger. Rat is, of course a water rat or what we have come to know as a European Water Vole. The book is a mixture of camaraderie, adventure and morality. I won’t give away the plot but it does have a happy ending.

See also

We will also meet two other rodents, [232] the House Mouse and [297] the Brown Rat.

We won’t see a Mole (never seen above ground) or a Badger (now being exterminated in large numbers by politicians to please farmers who mistakenly blame them for the spread bovine tuberculosis.) Toad will slip in disguised as a frog in [295].

[I hope all my non-English speaking readers understand that ‘mice’ is the plural of ‘mouse.’]