Current factors affecting Red Squirrels

Competition from the Introduced Grey Squirrel

Evidence from further south continues to suggest that the presence of grey squirrels is
detrimental to the local red squirrel population. The reasons are yet to be understood. However,
it is thought that the grey's ability to have a wider range of diet than the red's, combined with
a fast colonisation rate, all act to gradually force red numbers down. Grey squirrels can digest
acorns more efficiently than red squirrels. Because grey squirrels can eat hazelnuts before they
are ripe, there is a reduced availability of a valuable end of summer food source for red
squirrels. It is now known that the presence of corridors of large seeded broadleaves, such as
oak or beech, is frequently required for the grey squirrels to arrive and colonise in areas
previously occupied only by red squirrels.

Evidence from research in Wales has shown that even where grey squirrels have taken up
residence in conifer areas, they still rely strongly on large seeded broadleaves for food,
especially in times of a light cone crop. Research is continuing and new details are being
discovered all the time.

Habitat Destruction

Loss of habitat can arise through a variety of factors. Large-scale forestry clearfells can destroy
or isolate communities, as red squirrels are vulnerable on the ground and require some linking
corridors of trees and shrubs that will provide cover and reduce predation.

The planting of Sitka spruce as a monoculture is thought to provide a poor habitat for red
squirrels due to its unpredictable coning cycle. Also, the small seeds produced do not remain
viable for as long as seed from some other conifer cones.

New housing or other development may also pose a serious threat to established red squirrel colonies, by isolating or destroying resident communities. The use of large seeded species in landscaping may also cause a future hazard. Current research suggests that the minimum area of woodland required for a colony to be self-sustaining, is 200 ha. This may include adjoining woodlands, but any disruption of these areas could have serious repercussions for the existing population.

Road Kills

A number of red squirrels are killed as the result of road accidents, particularly on smaller, less
well-used country roads where there is woodland bordering either side of the road.

Disease

There is evidence in England that Parapox virus, fatal to red squirrels, can be carried by grey
squirrels. This disease has not yet been discovered in Scotland, but the medical examination
of both red and grey corpses is essential in the monitoring of this disease.

Predation

Red squirrels that come to gardens to feed are vulnerable to predation from domestic cats,
particularly if they have to cross open ground to get to feeding stations. Natural predators of
red squirrels include pine martens and some birds of prey. It should be noted that
predators are just as likely to take grey squirrels as reds.

Current Action

The Grampian Squirrel Group, formed in 1999, is a combination of government bodies such as
the Forestry Commission and Scottish Natural Heritage and private landowners including the
National Trust for Scotland, and a number of private estates, as well as interested individuals.
The Group is part of the Scottish Squirrel Group, which acts as a forum to co-ordinate
activities aiming to conserve the red squirrel in Scotland.

The Scottish Squirrel Group is represented on the UK Red Squirrel Group, which facilitates
the co-ordination of red squirrel conservation throughout the UK.

The Scottish Squirrel Group are encouraging all squirrel groups to identify priority areas where
red squirrel populations appear stable, and which can be targeted as a focus for conservation
management. A priority area may be a mixed conifer woodland over 200 ha in size, supporting
a healthy red squirrel population.

A major objective of the Grampian Squirrel Group was to carry out a survey of the Grampian
area. This was completed in 2000.