Dave Tosh, from the School of Biological Sciences at Queens University, found the greater white-toothed shrew in Tipperary and Limerick while working with University College Cork and BirdWatch Ireland. Its natural range is in parts of Africa, France and Germany and before now the closest it has been spotted to Ireland is in the Channel Islands.
As part of his PhD, Dave was studying the diet of the Barn Owl in Ireland. Last winter John Lusby, Barn Owl Research Officer from Bird Watch Ireland, sent him pellets (regurgitated food remains) from owls in Tipperary and Limerick to help with the study.
Dave explained: "It was amongst a batch that I was about to dry in an oven, that I noticed a very large shrew skull.
"Having looked at hundreds of pellets from Ireland already I knew that what I was looking at was very unusual as our native pygmy shrew is very small in comparison.
"I ended up looking through more and more pellets and discovered more and more of the strange shrew skulls."
In March seven greater white-toothed shrews were trapped at four locations in Tipperary and their existence has just been recorded in the scientific journal Mammal Review.
Professor Ian Montgomery, Head of the School of Biological Sciences at Queen's, says the animal is likely to have been introduced recently to Ireland and the discovery of a new mammal species in Ireland is extremely rare.
"Most species which occur in Ireland also occur in Britain but the nearest this species of shrew has been found is on the Channel Islands and the Scilly Isles.
"These records are evidence of at least one recent introduction event, probably accidental, from continental Europe to Ireland and has resulted in a rapid increase in numbers over a short period."
The discovery, however, raises issues related to ecological impact and control which need to be further researched. While the shrew is likely to sustain threatened birds of prey including the barn owl, it could lead to the loss of small native mammals including the pygmy shrew.