An international team of researchers led by scientists at the University of York in the United Kingdom have used mitochondrial DNA to show that the timeline of house mice migration across the upper north Atlantic through Scotland and the Scottish Islands, to Iceland, Greenland, and Newfoundland closely matches that of the Viking invasion.
The Vikings, who fought, raided, and explored their way across the north Atlantic from the late eighth to the mid-tenth centuries were the scourge of most of Europe at that time, raiding, killing, and pillaging large swaths of the continent, not just the areas above, but also parts of England, Wales, the Isle of Man, and Ireland. They established the first cities in Ireland. They founded the duchy of Normandy, in France, and they even established a kingdom in Sicily in the Mediterranean Sea.
It seems that where they went, their house mice (scientific name Mus musculus) went with them, at least on the northern part of their journey.
According to a press release (see here) the research team, made up of members from the UK, US, Iceland, Denmark, and Sweden, used techniques designed to characterize genetic similarity, and thereby infer the relatedness of one population, or one individual, with another, in order to determine a mouse colonisation timeline.
They obtained modern samples of house mic DNA and compared them to ancient samples dating mostly from the 10th to 12th centuries. Samples were collected from nine sites in Iceland, Narsaq in Greenland, and four sites near the Viking archaeological site, L’Anse aux Meadows, in Newfoundland. Ancient samples came from the Eastern and Western settlements in Greenland and four archaeological sites in Iceland.
When analyzed, the samples showed that house mice traveled with the Vikings to Iceland in the early 10th century , either from Norway or the northern part of the British Isles. From Iceland the mice continued their journey on Viking ships to settlements in Greenland. However, while descendants of these stowaways can still be found in Iceland, the early colonizers in Greenland have become extinct and their role has been filled by Danish house mice (same species) brought much later by a second wave of European human immigrants.
Of significance is the fact that no evidence of house mice was found in the Viking settlement in Newfoundland, nor was there any evidence of ancestral Viking house mice DNA in modern house mice there. So, it seems that if the mice made if as far as Newfoundland, they became extinct before they could contribute to the modern house mice lineage on the island.