The final chapter of Kevin Danaher's book Irish Customs and Beliefs begins with an anecdote from the author's youth. He relates encountering an old woman named Nellie while on a family vacation in Clare, who, he discovers later, is known through the area for her herbal cures and propensity to curse anyone who offended her. He ends the passage by saying,
"On the way home that day I couldn't help thinking that the old lady was very like the witch in the story books; the black cat in the hearth and the heather besom behind the door were just what a witch should have, and when I heard of her cures and curses my suspicion grew. But I soon found out that the classic figure of the witch cleaving the night air on a broomstick with her cat perched on the pillion was not recognized in local tradition. Old Nellie might be a bean feasa, skilled in cures and in divination, or even an old cailleach who stole the cows milk disguised as a hare, but not a witch." (Danaher, 1964, pages 121-122).
This nicely illustrates a key difference between the Irish view of witches and the more well known continental one. While European lore paints a vivid picture of the witch flying through the night to unholy meetings and using her powers to torment her neighbors, wither crops, and generally spread misery, the figure of the Irish witch is markedly different. While still seen as negative and working against the community the tone of Irish witches in folklore is generally less severe. The most commonly written of way that an Irish witch might vex her neighbors is by stealing the milk from their cows or otherwise bewitching the cattle. This would be accomplished by the witch shapeshifting into the form of a hare and sneaking into the field (O hOgain, 1995). The more sinister view of witches seems to have been imported from Europe at a later time and never took the strong hold on the country that it did elsewhere, notably in Scotland (Danaher, 1964). Rather we see the idea of two types of magic users, the bean feasa (wise woman) who helped the community with herbal remedies, divination, and advice (especially relating to the fairies), and the cailleach who was envisioned as an old woman intent on stealing the milk from the cows and more broadly a family's luck.
Irish witches were well known to be able to take the shapes of both hares and weasels. There are several stories of farmers or hunters who are out in the early morning and spot a hare in among the cows, shoot it, and find later that a well known neighbor has been injured, having been the witch shapechanged (O hOgain, 1995; Wilde, 1991). It is perhaps because of this association that is thought to be bad luck for a hare to cross your path (Wilde, 1991). Similarly witches could take the form of a weasel and it was thought to be bad luck to cross paths with any weasel in the morning, although it was equally bad luck to kill it and risk it's spirit seeking revenge (Wilde, 1991). It should be kept in mind though that as with so many things in Irish folklore it could always be the fairies; indeed fairies were known to take the form of hares as well, particularly white ones (O hOgain, 1995).
Ireland had very few witch trials over the centuries and these were usually within settlements of those of non-Irish descent (Danaher, 1964). The last witch trial on record in Ireland occurred in Carrickfergus in 1711 and resulted in a conviction and a sentence of the pillory and a year in prison (Danaher, 1964). This seems to reflect the different attitude with which the Irish approached the subject, compared to the far more rabid witch-hunting that went on in Europe. Perhaps because the beliefs about witches were not as severe or perhaps because the belief in the supernatural and use of magic in folklore was so strong even after Christianization, the Irish witch never created the hysteria in Ireland that was the hallmark of Europe during this period.
Danaher, K., (1964). Irish Customs and Beliefs
Wilde, L., (1991). Irish Cures and Mystic Superstitions
O hOgain, D., (1995). Irish Superstitions