Hide and squeak: Tiny mammal gave science the slip

A TINY mammal, not previously known as an Irish inhabitant, has been discovered living quietly in the Tipperary countryside.

Eagle-eyed ecology research students followed up on their breakthrough by capturing seven members of the greater white-toothed shrew species at four locations in the county.

The tiny shrew had been previously “absent” from both Ireland and Britain but it occurs in the Channel Islands. It can also be found in parts of mainland Europe.

The discovery of the shrew in Munster is good news for Ireland’s threatened predators such as barn owls. But these wise birds had already been discreetly dining on the mini mammal before the scientists made the discovery.

Postgraduate students John Lusby of UCC and Dave Tosh of Queen’s University Belfast identified the remains of Crocidura russula (the shrew’s official name) in regurgitated food pellets of barn owls and kestrels.

Over the recent autumn and winter months the food pellets had been collected at 15 locations in Tipperary and Limerick.

John Lusby had been collecting the food pellets as part of his PhD studies on the barn owl and collaborating with David Tosh.

Said John: “We noticed these large shrew skulls in the pellets and we knew they were different.”

Professor John O’Halloran of UCC, who is on the barn owl research team, suggested there is potential for the newly discovered species of shrew to “become a major prey item of avian predators in Ireland where there is an impoverished small mammal fauna compared to Britain”.

The three scientists are carrying out research to identify factors behind the recent dramatic decline of barn owls in Ireland. Estimates suggest there are only 300 breeding pairs left in the country. The main reason for the drastic decline is loss of habitat, hunting and secondary poisoning by eating poisoned rats and mice.

Arguably Ireland’s most beautiful wild animal, the barn owl is probably its most useful: a breeding pair will kill an estimated 3,000 rodents in a year.

Given the barn owl’s endangered status, the tiny shrew’s arrival might just be the owl’s “saving meal”. But it may not all be good news as the ecological consequences are uncertain.

Introduced species can represent a global threat to biodiversity and can overwhelm native species within their new territory. An example in Ireland and Britain is the North American grey squirrel that has largely replaced the native red squirrel.