Northern Ireland

Greater white-toothed shrew spreads across Ireland

Greater white- toothed shrew Image copyright Ruth carden ucd
Image caption Greater white-toothed shrews could colonise abandoned farmland across Ireland by 2050.

An invasive species of shrew is spreading across the Irish landscape at a rate of more than five kilometres a year, according to new research.

Greater white-toothed shrews were first discovered in Ireland in 2007.

They have greyish brown hair and a yellowish grey lower belly.

The shrew have distinctive bright white teeth, prominent ears and long, white hairs on their tail.

Prof Ian Montgomery, Queen's University Belfast, said: "The invasive small mammals of Ireland, the greater white-toothed shrew and the bank vole should be recognised as an invasive species that has the potential to have a large negative impact on the Irish ecosystem."

He added that "the ecological impact of these alien species is likely to be far greater than, for example, the grey squirrel."


Scientists fear the greater white-toothed shrew could colonise field boundaries and abandoned farmland across the entire island by 2050.

Dr Allan McDevitt, University College Dublin, said "the invading population of the greater white-toothed shrew currently covers an area of 7,600 km2 and is found in Counties Tipperary, Limerick, Cork, Waterford, Kilkenny, Offaly."

The greater white-toothed shrew has a competitive advantage over native shrew, in eating large insect prey.

This advantage combined with a fast paced expansion could lead to the disappearance of the pygmy shrew, which has been in Ireland for thousands of years.

Image copyright Ruth carden ucd
Image caption The Pygmy shrew is one of the world's smallest mammals

Limiting the impact

The invasive species has not yet crossed the River Shannon.

However, it is understood that rivers and other barriers are only a temporary hindrance for the greater white-toothed shrew.

Research suggests the only means of limiting the impact of invasive small mammals is to encourage bigger hedgerows and more deciduous woodland across Ireland.

These habitats favour indigenous species against invaders.

Prof Montgomery said: "Ireland has a pitifully small area of woodland.

"Biodiversity would be greatly enhanced by a serious effort to increase the ecological value of hedgerows and expansion of woods and forests throughout the island. "

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