Mice hitched a ride with Vikings to mount their own invasions in the 10th Century, research has shown.
Scientists compared modern mouse DNA with ancient samples from mouse bones found at archaeological sites.
The analysis showed that the house mouse, hitched lifts with Vikings from either Norway or the northern British Isles to Iceland. From Iceland, the mice continued their Viking voyages to settlements in Greenland.
However, no trace of the Norse mice could be found in Newfoundland, even though the Vikings are known to have reached the Canadian province.
Professor Jeremy Searle, from Cornell University in the US, said: " If mice did arrive in Newfoundland then, like the Vikings, their presence was fleeting." The research is published in the online journal 'BMC Evolutionary Biology'.