SPECIES OF THE WEEK
Mustela erminea hibernica
The Irish stoat is widespread throughout Ireland and is a distinct sub-species confined to Ireland and the Isle of Man. They are often mistakenly called weasels in rural areas, but weasels are not found in Ireland.
The main difference in the Irish stoat is the dividing line between the chestnut-brown fur and the cream underside, which is usually irregular, and the hair on the upper lip is brown in the Irish stoat, also there is no white edge on the ear. The tip of the tail is always black. They do not normally become white (Ermine) in winter, due to our climate and lack of sitting snow.
Irish stoats have long thin cylindrical bodies and short legs. Males are larger than females with the average adult male measuring up to 40cm for the head and body while the females are shorter measuring up to 30cm. Stoats have long slender tails in proportion to their bodies which have a distinctive black tip at the end, males grow slightly longer tails than females which can measure up to 14cm in length. Adult males weigh up to 400 grams with females being much lighter weighing on average 200 grams. Unusually for mammals there is a noticeable difference in the size of the Irish population of stoats with individuals in the south being bigger and heavier than those found in more northern areas. Stoats have excellent vision and largely hunt by sight, their senses of smell and hearing are also well developed. They are good climbers, can swim well if required and able to run quite fast for short distances using a bounding stride interrupted to stand upright on their hind legs to survey the area.
They can be found in woodlands, hedgerows, marsh, heather, lowland farms, moorland, coastal areas and mountains. They prefer open woodlands and rocky scrub covered areas, on agricultural lands they would be near stone walls, ditches or hedgerows.
Irish stoats are skilled hunters they generally prey on rodents, birds, rabbits and insects. Male stoats will stalk and kill prey much larger than themselves, while females concentrate on smaller mammals like shrews, mice and rats. A single strong bite to the back of the neck is the favored method of attack for stoats. While they are largely carnivorous they will supplement their diets with berries and fruits depending on availability. While above ground stoats use their eyesight to locate prey such as birds, reptiles and voles while they use their sense of smell if hunting rabbits or rats below ground. Stoats are good climbers and will eat bird’s eggs from the nest, and as competent swimmers they can hunt fish in slow moving rivers.
The main breeding season for the Irish stoat begins in May and ends in July. An unusual adaptation for small mammals sees a long delay between mating and when gestation begins, this is done to ensure that the young are born the following year in early summer to avail of better conditions and food supply. Irish stoats produce one litter per year with each litter of five to twelve young known as kits. When born they are blind, deaf and have a light covering of fluffy white fur weighing only 4 grams. They are totally dependent on their mother and are fully weaned after five weeks. Rapid growth will see the young stoats becoming fully independent after twelve weeks by which time their mothers will have taught them several hunting techniques which they will need when establishing their own territories. Another unusual reproductive trait of the Irish stoat is that some female kits can become sexually mature after only a few weeks, if mating occurs with an adult male then the young stoat can become pregnant while still being weaned by her mother although the delayed gestation period of stoats means she will not give birth until the following year once she sets up her own territory.
The Animal Ecology & Conservation Group, NUIG, with the support of The Vincent Wildlife Trust, are carrying out a nationwide study of the Irish stoat. If you have any information on the Irish stoat, especially sightings, please fill in our online survey form at:
Photo by Carrie Crowley