A TALE OF TWO SQUIRRELS

The fall of the reds

The red squirrel (Sciurus vulgaris) is native to the British Isles. It once lived in all wooded areas although its numbers seem to have fluctuated widely from year to year. Since the 1920s and 30s, its range has shrunk on mainland Britain, and it is now almost extinct in lowland England and Wales. Populations are disappearing in Scotland and across Ireland.

The rise of the greys

The grey - or gray to use the American spelling - squirrel (S. carolinensis) from eastern North America is slightly larger and stockier than our red squirrel. Liberated in up to 35 sites in the British Isles from 1876 to 1920, it expanded rapidly across England and Wales from about 1930 to 1950. It is still advancing northwards. Greys now dominate the Scottish lowlands and much of Ireland. Introduced grey squirrel stocks reach a far higher density than native reds. A run of mild winters and good seed or mast crops of oak and beech nuts means grey squirrels can breed here for most of the year, boosting their populations still further. Climate or global warming may be an added bonus for them. The rise of the greys and fall in distribution of the native red squirrels appear linked. The picture is complicated but disease and competition for food and space are implicated. What is sure is that as the greys appear, the reds disappear. The sad truth is that the American cousin is bigger and better at living in our woodlands than the native British red squirrel is.

A successful invader

The grey squirrel boasts all the attributes of the successful invader - good birth rate, omnivorous, opportunist, diet and high tolerance of its own population density and of mankind. Thanks to its heavier adult weight and higher population density a typical grey population needs up to 20 times more food than a typical red population - making a serious impact on the local environment. It digests foods more efficiently too.

The problem

Often regarded as an attractive, mischievous animal with bright eyes and a bushy tail, the grey squirrel is a nuisance or pest in many situations. Greys have now penetrated our innermost cities damaging parks and garden plants and even houses, where they have invaded roof spaces, damaging insulation and wiring. Courtesy of ESI

...damage to trees Market gardens, orchards and farms can suffer serious economic losses when this addition to the UK fauna raids crops. It is a major pest in woodlands and forests. Especially in early summer, grey squirrels can strip the bark from the base, trunk or crowns of trees. They do this to an increasing number and variety of both native and introduced trees. From a forestry viewpoint, that slows growth, degrades the timber value and reduces productivity and profitability. If grey squirrels remove the bark right round the stem - called ring-barking or girdling - the upper part of the tree or branch will die. Where smaller patches of bark are chewed off, corky callus tissue may eventually heal the wound but often infection and rot have set in by then and the timber value of the wood plummets. Grey squirrels seldom debark trees in their native woodland habitat in North Eastern North America. In the UK, this practice is accredited to either feeding on the sugary phloem under the bark or to agonistic, territorial type behaviour - but is often a bit of both. Bark-stripping occurs mainly from May to August. Broadleaf trees are more vulnerable than conifers and trees aged 10-40 years are particularly susceptible. Sycamore, beech and oak are the most attacked common species but most tree species suffer and the habit is spreading. The only means of preventing unacceptable damage at present is by reducing the number of grey squirrels by shooting, trapping or using toxic bait in special hoppers. Immunocontraceptive trials have proved impractical. Protecting each tree individually is impossible.

...changing woodland make up

Ancient woodlands, such as Burnham Beeches or the Forest of Dean, which have been subject to grey squirrel attack for decades, are now showing a further effect of the grey on the landscape - the long term natural life cycle of the forest is being disrupted as bark stripping prevents the next generation of forest giants from maturing.

...impact on native biodiversity

Once regarded as just a pest of commercial forestry, the grey is now seen as a much wider environmental threat - displacing the native red, plundering birds nests and competing for food with smaller native mammals. Grey squirrels are implicated in the decline of the native red squirrel. Greys probably impact negatively on declining hole or crevice nesting birds such as woodpeckers, nuthatches and tree creepers.

Helping the red

red squirrel © Forestry CommissionMeasures tried to give red squirrels a helping hand in their four remaining habitats include giving them top-up food in special hoppers and tightropes strung between trees to encourage them to cross busy roads safely. Projects like "Red Alert" in the Lake District are taking action to assist the native red squirrels. But so far, efforts to save red squirrels in their last refuges in coniferous forests here have only stemmed the incoming tide of the colonising greys.

What now?

There are now over 2.5 million greys in the UK but fewer than 150,000 reds remain. Greys occupy most of lowland England and Wales, and much of the Scottish midlands. Red squirrel colonies survive under siege in northern England and the Scottish borders, the red population in England and Wales, and even Scotland, could soon be reduced to survivors on a few easily defensible islands like Brownsea, the Isle of Wight or Anglesey. Without resolute national action our native red squirrel seems doomed on the mainland, and our natural biodiversity will remain under attack. But the grey squirrel is not just a UK problem - its impact could spread far wider.

A European context

The World Conservation Union (IUCN) - a United Nations organisation - lists the grey squirrel among the World's 100 worst invasive alien species. The grey squirrel threatens biodiversity, forestry and the environment in three EU nations: UK, Ireland, and Italy. Grey squirrels introduced into in Northern Italy are spreading northwards with the Alps now in their sights. If nothing is done, greys will cross from Italy to neighbouring countries and eventually to all of Western Europe. A European solution is needed for a European problem. The grey is without any natural enemies in Europe. In Ireland, the grey is well established, widespread and spreading to the demise of the reds.

The European Squirrel Initiative (ESI)

The European Squirrel Initiative believes there is only one way to save the red squirrel in Britain: the grey must go. The public understands this - a recent poll found that 69.7% of the population was aware that greys were driving reds to extinction, and 68.2% would support control of greys, while 63% wanted Government to act. ESI was formally constituted in 2003, and in Autumn 2004 became a Registered Charity, with a clear and simple objective: - The restoration of the native red squirrel and the protection of the natural environment by removing the impact of the alien grey squirrel in Europe.

ESI has two roles, firstly to inform and educate the public, politicians and officials about the real nature of the grey and its threat to the environment, secondly to encourage research into better ways of protecting the native red, and of eradicating the alien grey. Their web site is at www.europeansquirrelinitiative.org

A number of articles on both saving reds and controlling greys are on the Forestry Commission website at www.forestry.gov.uk . Visit "publications" and then key in search words or FC Practice Note 4. Controlling Grey Squirrel Damage to Woodlands (April 2004) Forest Research - www.forestresearch.gov.uk/greysquirrels

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