THE IRISH STOAT SURVEY 2023 – 2025

By RUTH HANNIFFY

This spring we invite the public to report their sightings of one of Ireland’s most elusive and littleknown mammals: the Irish stoat.

e Irish Stoat Survey, launched in February 2023, aims to collect records on a species that is believed to be common and widespread, but for which there are signi cant knowledge gaps. Stoats do not impact human or economic interests and are also di cult to survey, factors that o en lead to the species being under-studied with no data on population estimates or trends. e Irish stoat, or easóg as gaeilge, predates Mesolithic humans in Ireland. Fossil bones found in a cave in County Cork date the species to between 27,000 - 35,000 years ago, with compelling evidence that the species survived the last ice age under the snow. It is a subspecies endemic to Ireland and the Isle of Man, hence the Latin name Mustela erminea hibernica. e Irish stoat di ers in appearance from stoats found across Europe. It is generally smaller in size although, interestingly, stoats in the south of Ireland are larger than those in the north. Unlike its counterparts in Europe the fur does not turn white in winter and the line dividing the chestnut-coloured upper fur and the creamy-coloured fur on its belly is usually irregular, rather than straight. Like all stoats however, it has a distinctive black tip to its tail. Stoats are members of the Mustelid family and are related to the

Irish Stout by Carl Morrow

otter, badger, pine marten and American mink. The characteristic ‘mustelid’ shape of a long sinuous body and short legs gives the stoat its recognisable bounding movement. There are no weasels in Ireland, so the stoat fills the niche occupied by both species in other places, and it is legally protected through the island of Ireland. The Irish stoat occurs wherever there is sufficient cover, particularly woodlands and scrub, and is frequently seen on coasts. Stoats den in the burrows taken over from rabbits, their preferred prey species, and will also eat rats, birds, shrews, mice and voles.

Monitoring stoats is challenging as these elusive carnivores leave few field tracks and signs. The Vincent Wildlife Trust has undertaken three studies of the Irish stoat. In 2010 Kate McAney, with the help of 50 volunteers, surveyed hedgerows in 50 10km grid squares across County Galway. The survey collected hair samples using 600 baited hair tubes, which were analysed for DNA at Waterford Institute of Technology. The survey detected stoat in 21 of the 50 survey squares, showing that hair tubes are an effective method for detecting stoats in the Irish countryside.

In 2017 the Small Mustelid Foundation in the Netherlands designed the ‘Mostela’. This modified camera trapping device comprises a wooden box with a tunnel inside, monitored by an internal motion-activated trail camera. It combines the benefits of a trail camera with the tendency of the inquisitive stoat to enter small spaces. VWT undertook studies in 2019 and 2021 using this device. We added an external camera to ensure we recorded ‘tube-shy individuals’ who avoided entering the Mostela. These studies highlighted that the Irish stoat was present at seven of the 12 study sites on the Galway-Mayo border and favoured woodland and scrub habitat particularly with stone walls, and also limestone pavement. (All studies are available at www.vincentwildlife.ie/download_ category/irish-stoat).

Although elusive, stoats are captivating creatures when one is lucky enough to catch a glimpse of one in the wild. They are wondrous creatures, and are fascinating to watch as they frantically race about the woodland floor like a high speed pin-ball machine. I remember sitting on rocks by the sea in Galway, a favourite perch of mine, and my surprise as a stoat bounced past. Even more surprising was that it stopped for a few seconds and held eye contact with me, a silent exchange between mammal and mammologist. I now understand why our ancestors greeted a stoat politely for fear of the consequences!

Irish mythology is rich with references to these intriguing creatures, and my few Irish stoat encounters rank among my personal wildlife highlights.

For many of us, our first encounters with this little animal were from the pages of ‘A Basket of Weasels’ and ‘An Irish Beast Book’, by the recently deceased Professor James Fairley. These books continue to instil a love of terrestrial mammals, in particular the mustelids, in many generations in Ireland. In ‘An Irish Beast Book’ Professor Fairley includes the following excerpt from Topographica Hibernica, written around the 12th Century by Giraldus Cambrensis, and it is a fitting portrayal of the Irish stoat: ‘This little animal has more spirit than body, and its courage supplying the deficiency of its strength, with a great heart actuating a slender frame, it is vindictive and relentless in its wrath’.

The Irish Stoat Survey will run for two years and is a collaborative project between the Vincent Wildlife Trust, the National Biodiversity Data Centre, University of Galway, Centre for Environmental Data and Recording and partners on the Isle of Man. Please submit any observations of stoats, including live animals or dead specimens such as roadkill (observations only), to the National Biodiversity Data Centre (Rep of Ireland) and the Centre for Environmental Data and Recording (Northern Ireland). Follow the Irish Stoat Survey Facebook and Twitter pages for updates and distribution maps.

For queries email: Irishstoat@vincentwildlife.ie

Ruth is the species conservation officer with the Vincent Wildlife Trust