The Faroese post issued two stamps depicting the Brown Rat and the House Mouse.
Brown Rat (Rattus norvegicus) 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 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 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. 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 (Mus domesticus)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 which is caused by the mouse marking its territory with urine. 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. 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. 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.