Botanic Gardens - Resident Grey Squirrel
There are two types of squirrels in Ireland, the red squirrel and the grey squirrel. The red squirrel is native to Ireland while the grey squirrel is native to North America.
The red squirrel (Sciurus Vulgaris) belongs to a large group of mammals called rodents (Rodentia), which includes rats and mice. They can vary hugely in all shades of red and brown to almost black, and their bushy tail at 20cm is nearly as long as their body. This tail helps them to balance as they climb and jump through trees.
A red squirrel is only half the size of a grey squirrel, and the long ear tufts are found only in red squirrels.
Their home (called a drey) is like a large bird’s nest lined with moss and twigs. Baby squirrels (kits) are born between February and August. There may be two litters in a year, with up to six kits in a litter. Few squirrels live beyond six years, due to starvation, disease, predation, or human interference with their habitat.
They do not hibernate, but rely in winter on buried nuts and small seeds.
The grey squirrel is also a rodent. Rodents are one of the most successful groups of mammals, with 1700 species. Most rodents are small, and all have strong sharp front teeth (incisors) which grow throughout the animal’s life. So rodents have to gnaw constantly at their food, which helps keep their teeth at the right length.
The grey squirrel is a good bit larger than a red squirrel. Measuring up to 48cm from nose to tip of tail, and about half a kilogram in weight, there is little difference between males & females. The thick coat is greyish-brown, with a slight reddish tinge in summer. The tail is grey, very long and bushy. The ear tufts are also much less visible than on the red squirrel.
The Grey Squirrel, introduced into Ireland , from North America remains the greatest single threat to current red squirrel populations. Competition from the grey squirrels generally result in the displacement of red squirrels from broadleaved habitat within 15 years.
In Ireland, the current population originates from a few individuals that were introduced into Castleforbes Estate, Co Longford in 1911.
Fortunately, dispersal of grey squirrels in Ireland has been slower than that experienced in England and Wales. This may be attributed to the existence of much smaller areas of broadleaved habitat, and fewer mature hedgerows which act as corridors along which the grey squirrels can travel. Both squirrels compete largely for the same food in a broadleaved woodland. Grey squirrels hold an advantage where food is limited, due to their ability to consume unripe food such as hazelnuts in October. The red squirrel, however, can only ingest ripened nuts, and therefore it is more likely to suffer from food shortages over the winter months. Red squirrel densities tend to be lower than greys, particularly where food shortages exist. This may be a direct result of lower breeding rates when the prevailing conditions are unfavourable. Where food supplies are plentiful, red squirrels appear to breed at similar densities to greys.
Red squirrels are one of the oldest native Irish species, in that they pre-date human history and were common at the end of the ice age when forests covered most of the landscape. However, it is widely believed that the red squirrel became extinct in Ireland in the early 1700's. Tree cover in this period had dwindled from 80% of the land area which occurred after the last ice age 10,000 years ago, to below 2% of the land area. Fragmentation of the remaining broadleaved habitat was probably one of the main reasons for the red squirrel's disappearance. The red squirrel was re-established at ten sites throughout Ireland, between 1815 and 1856, and these were derived from squirrel populations in England. They did very well and became common again in woodlands. However, in recent years, competition from the grey squirrel has pushed them once more down the road towards extinction.
There are 250,000-300,000 grey squirrels in Ireland, but only 50,000-100,000 red squirrels: the red squirrel is disappearing by 1% every year.