Where did I come from Mammy?

Eanna Ni Lamhna queries the provenance of some “Irish” small mammals.

I was in an English chain electrical shop in Dublin sometime ago and couldn't believe my eyes when I saw that they were selling mole deterrents. I asked the young fellow behind the counter if these things actually worked. He said he didn't know because he hadn't sold any. But when I asked why there was no demand for these things in Ireland he just shrugged. He had no idea. The answer is, quite simply, we have no moles in Ireland to be deterred, unlike Britain, where the creatures reside quite happily under lawns, which erupt sometimes into molehills as they tunnel underneath.

In fact compared to Britain we have very few small mammals – two mice species, one shrew species and one vole species. In Britain the native small mammals comprise three species of vole, three species of mouse, one dormouse species, three shrew species and one species of mole. This is because after the Ice Age Britain remained joined to Europe by a landbridge for a further thousand years after Ireland was separated and there was time for all these to scurry, burrow and scamper across. While it was generally assumed that the house mouse was introduced here, albeit unwittingly, we always thought that at least the field mouse and the pygmy shrew were true natives, in that they had come here under their own steam across an earlier landbridge soon after the Ice Age ended. So imagine the surprise when a study by the University of York in 2003, revealed that our pygmy shrew is closely related not to the British shrew but to the pygmy shrew that inhabits Andorra. This shows that shrews came here directly from there with the Mesolithic people who came to Ireland from south west Europe seven thousand years ago.

Our bank voles are much more recent arrivals. DNA studies found their close relations in a part of Germany from whence the turbine for the power station at Ardnacrusha was sent in the 1920's. Apparently a bank vole or two was caught up in the packaging and was delivered to the north shore of Limerick when the turbine was unloaded at Foynes. It has now spread to Kerry, North Cork and Tipperary as well as all over Limerick.

Our field mouse is thus the only true native small mammal, at least until some thrusting PhD student decides to pick on it for their doctoral study. True native mammals are indeed a rare breed. This lack of native small mammal species is reflected in the dearth of their major predators: the owls. Only the barn owl and the long-eared owl are native here, with the short-eared as a winter visitor. The British list has these three as breeding residents as well as the tawny owl, the little owl and the snowy owl in northern parts. So don't be conned into parting with money for a tawny owl nest box- whatever takes up residence in it, it won't be a tawny owl.