Irish natives squirrels threatened by North American killer

The American grey squirrel ( sciurius carolinesis) is number one on Ireland’s top ten most unwanted list.

The arrival of grey’s into red squirrel (sciurius vulgaris) territory generally sounds the death knell for the native red squirrels; Whilst not posing an obvious threat to the natives, the greys compete for food and worryingly carry the parapox virus which is deadly for the red’s.

Over the centuries the red squirrel was hunted into virtual extinction; there are historical records of thousands of pelts being exported annually from Ireland. By the beginning of the 19^th century, the red had effectively disappeared prompting a series of reintroductions at country estates.

The first documented re-introduction was in 1815 on the Glanmore Estate, in County Wicklow, by Francis Synge, the great-grandfather of the playwright John Millington Synge. Synge had embarked on a massive vanity project embellishing his demesne set around Glanmore Castle which overlooked the Devil’s Glen; introducing a herd of sika deer, planting thousands of cherry blossom trees amongst the native oaks and planting exotic giants, sequoia and Chilean pines.

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Grey’s anatomy         

The red is about half the size of the grey and consequently more agile in the tree canopy, tending to spend less time on the ground preferring coniferous woodland, whilst the more robust grey is more at home in deciduous and mixed forests where its more omnivorous diet can include in addition to seeds, berries, and birds eggs.

The grey has a long bushy tail, short front legs, and a rat-like head. The greys have some distinctive advantages over their smaller cousins; a longer life expectancy and a more rapid breeding cycle, their ability to digest unripened acorns and hazelnuts removes a potential food source from the Red’s as they are unable to neutralize the toxins.

In some instances, the grey’s greater bulk and ground feeding habits can be a disadvantage especially when large raptors and mammals; pine martins, foxes, and stoats are present.

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Furry frenemy

The pine martin is from the same family as the otter and like the otter, it was hunted for its thick brown fur which was highly prized by furriers. Following the introduction of legal protection in 1976 they have been slowly re-establishing themselves, spreading from the west and south with small numbers reaching the east coast. The pine marten bears a resemblance to a domestic cat and is similar in size with a long bushy tail and powerful claws which are ideal for tree climbing, hence the name cat crainn or tree cat in Irish.

There is growing evidence to suggest that the presence of pine martens who are native and naturally predate on red squirrels have a controlling effect on grey’s finding them an easier and more calorically rewarding prey.

It is hoped that the reappearance of Pine Martin in the woods around the Devil’s Glen will contribute to the survival of the dwindling red squirrel population, however, more help is needed; neglect by the Semi-state forestry body, Coillte has allowed laurel to colonize large areas of the forest floor and indiscriminate planting and clear-felling of Sitka spruce have resulted in a monocultural environment which is not conducive to biodiversity.

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Dukes of hazard

Six pairs of grey squirrels were introduced into Ireland from England, in 1911, at Castle Forbes, in County Longford, following a British aristocratic trend for beautifying country estates with exotic fauna and flora. The 11^th Duke of Bedford, Herbrand Russell imported ten grey squirrels, from New Jersey, releasing them at his Woburn Abbey Estate, in Bedfordshire, in 1890, contributing to the now 2.5 million greys in the United Kingdom. ironically Russell was President of the Zoological Society from 1899 to 1936.

Scot-free pine

The Scots pine (Pinus sylvestris) and the red squirrel have a close symbiotic relationship. Most if not practically all of the Scots pine in Ireland were originally introduced from Scotland. Until recently it was widely believed that all of the truly indigenous Scots pine in Ireland had been rendered extinct by a combination of climate change, leading to bogland encroachment, and felling. In 2016, a team of Trinity College botanists led by Professor Fraser Mitchell announced the discovery of truly indigenous Scots pines at Rock Forest in Co. Clare.

“All of these trees found in Ireland today were assumed to be descendants of the introduced Scottish stock, but that’s not the case. We analyzed pollen grains preserved in lake sediments to look into the natural history of this species, and those grains revealed its continual presence over the years at a location in east Clare.”

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Professor Fraser Mitchell

This keystone species is now being cultivated and is commercially available from Mountshannon Arboretum, in County Clare. The Scots pine was revered by the Druids associating the evergreen with the return of the sun after the dark short days of winter. Yule logs the precursor of the Christmas tree would most likely have been Scots pine.

The tree was exceptionally valued by the ancient Irish, regarding it as one of the Lords of the Forest (airig fedo) in their Brehon pantheon of Druidic law; pine resin was tapped and used for wood preservation and pitching for boats, or mixed with charcoal to form an excellent glue which was used in weapons manufacture, in particular the binding of arrowheads. The needles contain relatively high levels of vitamin C which can be made into tea whilst the nuts were a welcome mid-winter food and in times of famine the highly nutritious, mineral-rich, inner bark could be harvested and made into a fibrous porridge. This remarkable versatility may have contributed to its demise and consequently to the decimation of the Red Squirrel population.

The reintroduction of the Scots pine into areas like the Devil’s Glen could help to radically transform a struggling ecosystem into a flourishing sustainable environment:

“Scots pine also creates habitats for native Irish fauna, including many bird species. The increased conservation of Scots Pine that will result from our findings in Co. Clare will also benefit the conservation of many other Irish plants and wildlife. This work really shows the importance of understanding the past of our Irish biodiversity to best inform conservation efforts for its future preservation.”

- Alwynee McGeever Ph.D. researcher Trinity School of Natural Sciences.

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