Ireland's unlikely mammal

Ireland has few land mammals, and it was believed that no voles existed here until their discovery in Kerry in 1964. The discovery was a mysterious one because bank voles like dense cover and are an unlikely candidate to steal away a ship bound for Ireland's west coast. Their arrival is most likely explained by the Shannon Scheme of the 1920s which involved mass transport of machinery, including whole railways, from Germany by sea.

Genetic research supports the thesis that voles came from the European mainland, quite possibly Germany if there was a Mastjahre in the 1920s. 

During ‘mast years' (a regular occurrance in Germany) trees produce substantial seed leading to explosions in vole populations and may have caused an adventurous creature to seek pastures new.

More: Stuart et al (2007), Irish Naturalists' Journal
Volume 28 2007