THE BLACK RAT is now the only terrestrial mammal species to be considered threatened in Ireland.

This species has been categorised as “vulnerable” due to its very restricted distribution – it is only found on Lambay Island off the coast of Dublin.

However, the black rat is not a conservation priority and is in fact considered a threat to important colonies of cliff-nesting birds on Lambay.

The status of the species is included in the new Red List for Mammals for Ireland which assesses the conservation status of the country’s terrestrial mammals.

The document shows population improvements for the red squirrel, otter and Leisler’s bat since the last list assessment was carried out 10 years ago. At that stage, these three species were considered to be “near threatened” due to concerns about population declines.

More recent information, and in particular the results of large-scale monitoring programmes and national surveys undertaken and funded by the National Park and Wildlife Service (NPWS), demonstrate population recovery.

Josepha Madigan, Minister for Culture, Heritage and the Gaeltacht, welcomed the publication of the new list and said it highlighted the value of monitoring programmes managed by the NPWS.

All 25 terrestrial species native to Ireland or naturalised in Ireland before 1500 are included in the Red List assessment. The grey seal and harbour seal, which spend much of their time on land, are also included.

Bats and squirrels 

The document provides an assessment of the extinction risk of these species using the International Union for Conservation of Nature (IUCN) conservation status categories.

These categories, and the assessment framework that underpins them, are used globally to identify species most in need of conservation interventions due to their extinction risk.

A spokesperson for the Department of Culture, Heritage and the Gaeltacht said the list’s content is “very encouraging”. In a statement they noted that the Leisler’s bat population has increased by almost 30% since a monitoring programme began in 2004.

File photo of a Leisler's bat Frank Greenaway Frank Greenaway

“Ongoing otter surveys have confirmed that this species has recovered from any population declines and is widespread across Ireland.

“Most recently, work underway in NUI Galway with the support of NPWS and the National Biodiversity Data Centre is showing a remarkable recovery in red squirrel range. These three species have been down-listed from “near threatened” to “least concern”,” they added.

Despite the positive news, the list’s authors have highlighted concerns relating to habitat quality and noted that many of the natural habitats in Ireland are under threat. They have also identified areas of mammal ecology that require further research.