Ireland's own distinct and unique Stoat
The Stoat found in Ireland caused problems during Victorian times when the island of Ireland was part of the United Kingdom. British naturalists knew about the Stoat and the Weasel as both animals occurred on mainland Britain.
British Stoats and Weasels are difficult to tell apart in the field as both look pretty similar in that both are small, skinny, light brown animals with paler underparts. The Stoat is marginally bigger and heavier than the Weasel but that bit of information is of little use if just one animal is seen.
Stoats and Weasels are said to avoid each other so the chances of seeing both animals side by side for comparison are probably nil. Another problem is that it is normal to get just a fleeting glimpse of one of these animals.
If it proves possible to get a decent view of a mystery mustelid the clinching identification mark between the two species is that the Stoat has a black tip to its long brown tail whereas the Weasel does not.
The situation in Britain was quite clear to Victorian naturalists: there was the larger Stoat and the smaller Weasel. The situation in Ireland was confused as there was a medium-sized animal that was bigger than a Weasel but smaller than the British Stoat.
In 1895 two Victorian naturalists, Oatfield Thomas and Gerald Barrett-Hamilton, published a paper clarifying that the mystery mustelid found in Ireland was a distinct sub-species of Stoat. For the animal to evolve into a distinct sub-species it must have been isolated on the island of Ireland for a long period of time, possibly even pre-dating the last ice age.
So, mainland Britain has the British Stoat and Weasel while Ireland has its own distinct and unique Irish Stoat and no Weasels. Interestingly, the Irish Stoat also occurs on the Isle of Man.
Stoats in the northern part of Britain can turn white in winter and are the source of ermine, the luxury fur traditionally used on royal and judicial robes. The black spots on the white fur are the tips of the Stoats' black tails. The Irish Stoat doesn't turn white in our mild winters.
Stoats are a northern species extending north from Ireland to the Arctic Circle and south to the northern extremity of Spain. They have a circumpolar distribution sweeping around the globe from Europe to Asia to North America with some 40 sub-species recognised today.