Survey shows threat facing red squirrels
Saving Scotland’s Red Squirrels has published its 2018 survey, which indicates that while most of Scotland’s red squirrel populations remain stable, their welfare in southern areas remains under threat.
Since 2011, Saving Scotland’s Red Squirrels has been monitoring squirrel populations in the parts of the country where red squirrels are most threatened by the spread of non-native grey squirrels.
Grey squirrels, which were introduced to Britain from North America in the 19th century, out-compete red squirrels for resources and can also carry squirrelpox, a virus that does not harm them but is deadly to reds.
Previous survey results have indicated that red squirrel populations in the project’s focal areas had stabilised, a sign that with continued effort from conservationists and volunteers, the decline of Scotland’s core red squirrel populations can be halted. The 2018 survey results again make optimistic reading regarding the future of red squirrels in the north-east and the central lowlands.
In southern Scotland, however, while the proportion of survey sites detecting red squirrels has remained constant, the number of sites with a grey squirrel presence has significantly increased, suggesting that grey squirrels are continuing to move into what was previously ‘red only’ territory.
Although red and grey squirrels can live side by side for short periods, in most wooded landscapes, greys will typically replace reds within a few years unless efforts are made to reduce their numbers. When squirrelpox is present this process can be far more sudden and rapid as an infected red squirrel population can be wiped out within weeks.
Protecting reds in south Scotland is challenging because greys are spreading from the central belt and north from across the border. Greys also favour broadleaved trees such as oak and beech, which are more common in south Scotland.
The most positive survey results were found in north-east Scotland, where reds continue to expand their range, particularly around Aberdeen. Project staff are optimistic that with continued effort greys can eventually be completely removed from the region, which would enable reds to fully recolonise the city and at the same time remove a major threat from the important red squirrel populations in Grampian and the Highlands.
The north-east results are complemented by those from the central lowlands, where reds’ range has been maintained, indicating that the National Lottery-funded project is successfully protecting Scotland’s largest red squirrel population north of the Highland Line.
Mel Tonkin, Saving Scotland’s Red Squirrels project manager, said: ‘Grey squirrels have continued to spread in some parts of southern Scotland, particularly in the eastern Borders and in the Nithsdale area of Dumfriesshire. It is vital that the work we do in priority areas is stepped up to make sure that the red squirrel populations in these areas remain healthy.’
Squirrel populations are surveyed using feeder boxes placed in the same areas of woodland each spring. When a squirrel visits a feeder box, a sticky tab collects some of its hair, which can then be identified under a microscope.
The 2018 squirrel survey report can be viewed at scottishsquirrels.org.uk/ publications