The brown rat is larger than the black rat and the male is larger than the female. An adult brown rat weighs around 200-400 g and is approx. 21-29 cm long, with a tail length of approx. 17-23 cm. The fur is an even dark brown colour and lighter on the stomach. The head is pointed and the eyes are small. The ears are short and covered in hair.
The brown rat is also called the water rat. It originates from Asia and China and came to most of Europe in 1727, when it swam in large numbers over the River Volga. It had already arrived in Denmark in 1716, when the Emperor, Peter the Great, visited Denmark by ship. From Denmark, it was easy for the rat to spread northwards to Norway, the Faroe Islands, Iceland and Greenland. The rat came to the Faroe Islands on the Norwegian ship, The King of Prussia. The ship was on its way to Dublin, when it ran aground on the island of Lewis in Scotland. The shipwreck was driven north to Hvalba on Suðuroy in May 1768. The first rats arrived on the Faroe Islands via the wreck and had already found their way to Tórshavn by 1769. The brown rat is found on the larger islands only.
The rat is found everywhere, both in built-up areas and further afield; any place where it can find enough food. It is omnivorous and does not refrain from eating mice, eggs and baby birds, young hares and carrion. The rat generally stays in the same place, and if it finds sufficient foodstuffs, it will hoard for harder times.
The rat is a nocturnal animal. It is a good climber and moves around buildings, and can also find its way to the bird cliffs, especially to puffin holes. It can destroy the nests of Manx shearwaters and storm petrels completely. It lives in individual territories made up of one male and a number of females with young.
The female rat is fertile for 22 days, and mates 3-4 times a year, each litter giving approx. 6-12 young. Newborn rats are naked and blind, and reach sexual maturity at three months old. There are often many litters from the same warren, i.e. many rats in the same hole. The average life expectancy for a rat is about 1.5 years.
Attempts have been made to exterminate the rat population in all areas it is found, as they are seen as a source of disease among both people and livestock. It moves around all over the place and causes considerable damage: on the Faroe Islands, the rat has almost wiped out a number of bird species found on the bird cliffs. On those islands where rats are found, some species, such as the Atlantic puffin and the Manx shearwater (Manx puffin), have almost completely disappeared.
There are regulations concerning rat removal, which Faroese municipalities must comply with.
The House Mouse
The house mouse is grey/grey-brown and a little lighter on the stomach. The body is approx. 7.5-10.3 cm long; the tail is 7.2-10.2 cm long. The mouse weighs approx. 12-28 g. and has a somewhat distinctive smell; it can be this smell that draws your attention to the fact a mouse is close at hand, and is caused by the mouse marking its territory with urine.
The house mouse originates from Asia and was brought west by man. The Faroese mouse is part of the species West mouse (Mus domesticus), which is also found in Ireland, Scotland, England, France, Italy, Spain and Greece. One can thus assume that the Faroese mouse came to the Faroe Islands with the Irish monks, who were the first settlers on the islands. The first written mention of the mouse here dates from 1592, but in all likelihood it had already been seen on the Faroe Islands, when the first Norse Landnam settlers came here on their way to Iceland and Greenland.
In the North Atlantic, the mouse is clearly attached to people. It lives outside in the summer, but comes inside in the autumn. On the Faroes it is only found on individual islands, and on some of the islands where there are no rats, it can find its way to the bird cliffs during the summer.
Mice are not fastidious eaters, and consume what they can find from seeds, insects and leftover human food, though they prefer corn and corn products. They can survive without water, and thus live well in granaries and pantries. In houses, they can do considerable damage to food and furniture, being adept gnawers.
Mice can climb all over the house. They live here, where there is plenty of food and materials with which to build nests, during the frostier weather, hiding food away for harder times when it is in short supply. The mouse is a mating animal, with the female building the nest which the male visits during mating season.
Mice can reproduce all year round and can theoretically give birth to ten litters a year, with 3-6 young in each litter. The young reach sexual maturity when they are one month old. Attempts are made to control the rodent population everywhere mice are found, generally with mouse traps and poison.
Extract from the book ”Villini súgdjór í Útnorðri” (Wild Mammals in Western Scandinavia) by Dorete Bloch and Edward Fuglø (1999).