The Grey Squirrel
lives in the same sort of woodland habitat as the Red
and eats the same seeds, nuts and berries, however, it is
better able to digest large nuts such as acorns and hazel
nuts, found in broadleaved and mixed woodland. This in turn
leads to better growth and survival of the Grey Squirrel and
consequently better reproductive success than the Red. The
Grey is said to out-compete the Red Squirrel when they occur
together. In addition, Grey Squirrels can carry Squirrel Poxvirus
(SQPV), which is deadly to Red Squirrels - and although this
disease has not been recorded in the Highlands, it was reported
in the Borders just a few years ago.
Where Grey Squirrels occur, the woodland habitat that offers
most benefit to Red Squirrels is conifer forest because
these small-seeded trees do not give Greys a competitive advantage.
However, in recent decades, large-scale tree felling of mature
Scots pine and Norway spruce plantations and replacement with
Sitka spruce has been detrimental to the Red Squirrel because
it does not provide such a good or predictable food source.
Although the preferred
support for species is through broader habitat protection,
the Red Squirrel is an unusual species in this respect. To
protect Red Squirrel strongholds, it may be necessary to manage
and maintain forests that are of rather limited conservation
value in their own right. Careful management of commercial
forests, for example, producing mixed age plantations and
maintaining corridors to allow movement over large areas across
the tree canopy, is an important means of helping to conserve
the Red Squirrel. However, the Highland Red Squirrel population
is in a unique situation in the UK because there are no Grey
Squirrels. This last refuge for the Red Squirrel offers the
opportunity to learn about managing broadleaved and mixed
woodland for the benefit of Red Squirrel as well as conifer
forests. It is the only part of the UK where such work could
be undertaken without the added complication of enhancing
Grey Squirrel habitat in the process. This research is considered
a top priority of the Red Squirrel Species Action Plan (SAP)
for the Highlands (2003-2007). Such studies will also contribute
to the Habitat Action Plans for Upland Oakwood and Native
Pine woodland which are part of the Highland Local Biodiversity
Action Plan (LBAP).
In some areas of the Highlands,
Red Squirrels appear to be doing well, such as
those in the woodlands of Badenoch and Strathspey, near Inverness
and along Loch Ness. However, other locations where they might
be expected to thrive, notably Glens Urquhart, Moriston, Affric,
Strathfarrar and Glencannich Forest appear to be under-populated.
The reasons for these differences are not known and indeed
the distribution and abundance of Red Squirrels in much of
the Highlands is unknown. A key aim of the HRSG is to increase
this knowledge by engaging local volunteers to survey and
monitor Red Squirrel and to train them to do this in a scientifically
meaningful way. The data obtained will be collated by the
HRSG and stored in a central database, the Scottish Squirrel
Database that is held by SNH. These invaluable data can then
be used to prioritise activity and inform decision making.
This part of the project will contribute to the first strategic
objective of the Scottish Strategy for Red Squirrel Conservation
which is to establish the Red Squirrel resource and monitor
it.
A critically important part of managing
Red Squirrel habitat is to engage those
directly involved in activities that affect Red Squirrel survival.
Included are foresters, game keepers and land owners. For
the most part, there is a positive attitude to the endearing
Red Squirrel and problems arise from a lack of understanding.
The HRSG has a major role in educating and informing these
key people in the ways that they can benefit Red Squirrel
and avoid detrimental activity. Foresters, for example, may
not appreciate the importance of continuity in the tree canopy
for Red Squirrels which enables them to avoid exposure to
predation. The scale of the contiguous forest is also important
and for conifer plantations this needs to be at least 200ha
because of the low densities at which Red Squirrels naturally
occur (about 0•9 per ha) and the population size required
for it to be sustainable.
Management of Red Squirrel habitat is
not only important for optimising their survival and increasing
their numbers but also for reducing the risk of spreading
Grey Squirrels. The patchy distribution of woodlands in the
Highlands provides island-like refuges in a largely treeless
landscape. These open spaces are difficult for Grey Squirrels
to cross because they are seriously exposed to predation over
such terrain. In some instances, such as the restoration of
riparian (river side) habitat, there may be a danger of providing
corridors along which the Grey Squirrel could spread into
the Red Squirrel refuges. Where these refuges are broadleaved
or mixed woodland, the Grey is likely to out-compete the Red
and another refuge will be lost.
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