Seeing red as hit squad set to kill greys

Richard Collins on a death zone in Scotland for invading grey squirrels.

IN 122AD, the Roman emperor Hadrian built a wall between England and Scotland, the remains of which can still be seen today. The 117km fortification, manned by 24,000 troops, kept the Scots from raiding the towns and farms of their southern neighbours. Now a new defensive line is being established. This time around, it’s a Scottish population which needs protection from English barbarians.

The red squirrel has been in Britain since the end of the last Ice Age. A native species, its position remained secure until the late 19th century. Then grey squirrels were introduced from the United States. Greys don’t attack reds and their lifestyle differs sufficiently from their cousin’s that the two species should be able to coexist. However, once grey squirrels arrive in an area, the red population declines. This ethnic cleansing has been so thorough that the red squirrel is gone from almost all of England and Wales. There are now 3.3 million British greys and only 160,000 reds.

Marching northwards through Scotland, the greys now threaten the last red stronghold, the Caledonia pine forests where three quarters of British reds live. Conservation bodies, such as the Scottish Wildlife Trust, are worried.

The new squirrel wall won’t be a physical one, nor will it be positioned on the border with England. The bottom half of Scotland is being ceded to the greys and, with the blessing of Scottish Natural Heritage, the ‘red squirrel protection line’ will run from Invereray on the Atlantic coast to Montrose on the North Sea.

Any grey putting its nose over the peace line will be shot. Baited traps are being set. Farmers and land-owners have been invited to join a squirrel version of the neighbourhood watch scheme.

Needless to say, not everybody approves of the measure. The cute and cuddly grey squirrel is much loved and a heated debate had developed over what its detractors call the ‘killing line’. Ross Minett, campaigns director of Advocates for Animals, told RTÉ’s Mooney Show that “the killing of greys is morally wrong”. Nor will persecution work. “For every grey they kill, another moves in to replace it,” he claims,.

That the red squirrel is threatened by the presence of greys is not in doubt, but nobody really knows what actually causes the decline. Size may be a factor; the grey is much bigger than the red and it’s just at home feeding on the ground as in the trees. It crosses open country readily, enabling it to colonise new areas.

The red, the blue tit equivalent of the mammals, does come down from the trees but it’s more at home high in the canopy. It seldom ventures far from cover and this has led to ‘islandisation’; living in a fragmented patchwork of isolated communities, into which there is little genetic input from outside, and local extinctions are inevitable in times of stress.

The grey’s digestive system is much more robust than that of the red. It has enzymes to deal with the poisons broadleaved trees produce to upset the tummies of animals which eat their seeds. Reds can barely digest acorns and beech mast, preferring their traditional conifer seeds. But the grey’s most lethal weapon is a virus which it is believed to carry. Squirrel-pox does not affect greys but a red squirrel which comes in contact with it may die within weeks.

Campaigns to exterminate unwanted mammals have only occasionally been successful. The musk-rat was eliminated from Irish riverbanks in the 1930s. However, years of persecution and massive bounties paid for the killing of foxes had little or no effect on numbers.

Grey squirrels start to breed when a year old. The normal litter is three but up to eight have been recorded. Most females breed once a year but some have two broods. Such high productivity ensures that an adult which dies is replaced immediately by a young recruit. To have a significant effect of overall numbers, the exterminators will have to kill more squirrels than are being born each year, a tall order.