Our recent publication, 50 for the Future, lists 50 things that we believe should happen in Scotland over the next 50 years to benefit both people and wildlife. In this week's 50 for the Future article, Elana Bader. HLF Project Development Officer for the Saving Scotland's Red Squirrels project, highlights the plight of the red squirrel and what must be done to prevent it becoming extinct in Scotland.
Number 37: Secure the future of red squirrels by controlling grey squirrels and preventing them entering the Highlands
We can tell a lot about the history of a species by the scientific name that it was given. What do you picture when you hear Sciurus vulgaris, Latin for “Common Squirrel”? Do you picture the near ubiquitous grey squirrel? If so, you're mistaken. In fact, Sciurus vulgaris refers to the UK's only native and once common squirrel – the red squirrel.
Only a century ago, red squirrels were common across all of England, Wales and Scotland, but today only 160,000 red squirrels remain. About 75% of these are in Scotland, which is considered the last major stronghold of the species. So how did this happen?
The key cause of the red squirrel's decline and near total displacement on mainland Britain has been competitive replacement by the American grey squirrel (Sciurus carolinensis). Classed as an “invasive non-native species” in the UK, grey squirrels were introduced to sites in England and Scotland in the late 19th century, and after rapidly spreading now number at least 3 million across the UK.
The much larger grey squirrel outcompetes the red squirrel for food and living space, gradually replacing it over time. Whilst it appears quite at home in our parks, gardens and woodlands, the grey squirrel is actually native to the vast woodland network of eastern North America. When you see a grey squirrel in its native habitat, eating the very large acorns from an American oak, the fact that it is designed for that habitat – and not those of the UK – is really driven home.
The grey squirrel also acts as the natural host of Squirrelpox; a virus which is readily transmitted to red squirrels and which subjects them to a slow and painful death within two weeks in virtually all known cases. One study has estimated that the disease speeds up the replacement of red squirrels by greys by a factor of about 20 (Armitage et al 1997). Disconcertingly, the virus arrived at the Scottish border from northern England in 2005.
Saving Scotland's Red Squirrels was formed to halt the decline of the red squirrel and protect the remaining Scottish populations from the threats of the grey squirrel. The project is a partnership between the Scottish Wildlife Trust, Scottish Natural Heritage, Forestry Commission Scotland, RSPB Scotland, Scottish Land & Estates, and the Red Squirrel Survival Trust.
Through its work over the last seven years, the project has established that the red squirrel can survive in areas where grey squirrels and Squirrelpox also occur – for example across South Scotland – as long as the grey squirrel population density is kept sufficiently low to minimise both the competition and the transmission of the virus. This can only be achieved via strategically targeted and coordinated landscape-scale grey squirrel control, which has enabled red squirrels to re-establish in many areas.
In the Highlands of north Scotland, where there are no grey squirrel populations (apart from a small, contained population in Aberdeen), the objective is to protect the red-only populations from any grey squirrel incursion. As long as large areas of the northern half of Scotland remain grey squirrel free, Scotland is the safest place left for red squirrels in the UK today. With the urgency created by the arrival of Squirrelpox in Scotland, it is clear that without management to counteract the spread of grey squirrels and the disease, red squirrels may become extinct in Scotland.
In order to secure the long-term survival of the red squirrel in Scotland, the next objective of the SSRS project is to facilitate community action. With the support of project staff, we want to inspire motivated voluntary networks that are capable of acting together to protect red squirrels in their local area. Without the help of the wider public, the large conservation task at hand would not be affordable. The contributions made by local communities will have an essential ecological impact, helping to safeguard the future of Scotland's valuable red squirrel populations.
For more information about red squirrels, the SSRS project, and how to get involved, visit scottishsquirrels.org.uk.
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Elana Bader is the HLF Project Development Officer for the Saving Scotland's Red Squirrels project at the Scottish Wildlife Trust