In Ireland the extinction of pygmy shrew is feared if the greater white-toothed shrew carries on spreading rapidly. Thanks to temporarily hindrance river Shannon that is stopping this recently discovered shrew to threat the existence of one of the world's smallest mammals - Ireland's pygmy shrew.

The pygmy shrew is one of the world's smallest mammals, weighing in at 3g-6g and is found in Ireland. They have iron deposits at the tip of their teeth which give them a red color. Whereas, the greater white-toothed shrew, weighs in at 8g-14g, and as their name suggests, they have distinctive teeth and have become a popular meal for birds of prey. They are believed to have probably come to Ireland hidden in a shipment of gardening supplies.

If numbers are looked into then it can be seen that this new species has outnumbering the traditional shrew in some parts of the country by 20 to three.

"Species can live together after invasions occur, but in this case, there may not be sufficient landscape complexity in Ireland to allow niche partitioning between these two species of shrew" ,said Dr Allan McDevitt from UCD.

He further added that they have appealed to the appropriate authorities in both the Republic of Ireland and as well as Northern Ireland to look into the issue of invasive species causing severe ecological impacts across the island.

Professor Ian Montgomery of Queen's University Belfast who has studied the phenomenon said that ensuring bigger hedgerows and more deciduous woodland may enable the protection of species against invaders.