Trial reintroduction of European beaver to Knapdale Forest – Advice and
Recommendations to the Scottish Government by Scottish Natural
Heritage.
8 May 2008
DOCUMENT 3
SNH’S APPRAISAL OF THE PROPOSAL IN RELATION TO POSSIBLE
EFFECTS ON KNAPDALE LOCHS SSSI, KNAPDALE WOODS SSSI,
EUROPEAN PROTECTED SPECIES, SCHEDULE 5 SPECIES, BADGER
AND KNAPDALE NSA.
CONTENTS:
1. KNAPDALE LOCHS SSSI
2. KNAPDALE WOODS SSSI
3. EUROPEAN PROTECTED SPECIES
4. SCHEDULE 5 SPECIES
5. BADGER
6. KNAPDALE NSA
7. SNH RECOMMENDATIONS
1. KNAPDALE LOCHS SSSI
The qualifying feature of breeding black-throated diver is covered by the
appraisal for the Knapdale Lochs SPA (see SNH’s appraisal of the proposal in
relation to possible effects on Taynish and Knapdale Woods SAC and
Knapdale Lochs SPA).
2. KNAPDALE WOODS SSSI
The qualifying features are;
• Upland oak wood
• Bryophyte assemblage
• Lichen assemblage
• Breeding bird assemblage
• Loch trophic range
• Dragonfly assemblage
The upland oakwood, bryophyte assemblage, lichen assemblage and loch
features are covered by the appraisal for the qualifying interests of the
Taynish and Knapdale Woods SAC.
Breeding bird assemblage – The main habitat changes caused by beavers
will be felling of trees and shrubs and the creation of wetlands/ flooded areas
within their range The majority of woody material cut by beavers tends to be
of small diameter (approximate range of 3-8cm) but they will fell larger trees.
Most of their feeding and other activity takes place in water or within 10m
(less frequently up to 100m) of freshwater edge. The proposed release sites
will be on the lochs. The beavers might dam outflow or inflow burns and thus
flood presently dry or damp areas. This could lead to the death of any trees/
shrubs in that area and/ or decrease the areas of open ground within the
forest mosaic. Overall we do not consider this to be a significant risk to the
breeding bird assemblage.
Impacts, if any, to the breeding bird assemblage are likely to be very
localised. Impacts to species using large trees or trees away from water are
likely to be negligible There could be some minor impacts to bird species
using the smaller trees and scrub, on the fringes of the water. However the
beavers are unlikely during the trial to remove that entire habitat in their
territories and there will be similar habitat present elsewhere in the SSSI away
from the areas used by beavers. The increase in open ground around the
lochs and any increase in wetland/flooded areas might lead to an increase in
species of those habitats. In conclusion there is not likely to be an adverse
impact to the overall breeding bird assemblage in the SSSI due to the
beavers.
Dragonfly assemblage – A number of species are recorded from the SSSI
with the hairy dragonfly Brachytron pratense and the beautiful demoiselle,
Calopteryx virgo being of most interest. The other species are well distributed
in the mid-Argyll and Argyll areas. B. pratense breeds on the edge of the
bigger lochs and its larval stages utilise floating detritus. If there was a lack of
such material through beaver feeding activity then this might have an adverse
impact on this species. On the other hand, removal of encroaching scrub on
the water’s edge with a corresponding reduction in shading might have a
beneficial effect on the species. Any potential raising of water levels by
beavers is unlikely to have an impact. This species should be monitored for
presence/absence and evidence of breeding in the trial site and the SSSI as a
whole.
C. virgo uses small burns and rivers and the adults display in the dappled
sunshine created by trees/ shrubs along these burns. If the tree cover closes
over and reduces the sunshine, the site is not used and conversely open
burns are also not used. The species has been recorded in the SSSI but it is
declining due to the tree and shrub regeneration along the burns. Therefore
patchy removal of scrub by beavers is likely to have a beneficial effect on this
species. Raising of water levels by damming of burns could perhaps affect
the species if the water became too deep for adults to lay their eggs on
submerged weed or the weed disappeared. This species should be
specifically monitored for presence/ absence along specific sections of
enclosed and open burns.
3. EUROPEAN PROTECTED SPECIES
The following European Protected Species (as listed on Schedules 2 and 4 of
The Conservation (Natural Habitats, &c.) Regulations 1994, as amended) are
found in the trial area;
• European otter Lutra lutra
• Bat species - Vespertilionidae
• Wildcat Felis silvestris
Otter is present in the trial area both within and outwith Taynish and Knapdale
Woods SAC (where it is an Annex II qualifying interest). The relationship
between otters and beavers is covered by the appraisal for the qualifying
interests of the Taynish and Knapdale Woods SAC.
Bat species - Daubenton’s bat, Natterer’s bat and pipistrelle bat species –
are present in the SSSI and could use the trial area for feeding and roosting in
trees and buildings. There is no evidence from elsewhere in Europe that
beavers have had any adverse impact on bat species. Tree roosts will be in
larger and older trees which have the necessary cracks/rotten areas. The
chances of beavers felling a large tree with an occupied roost are very low,
given most activity is close to water where there are generally fewer larger
trees. Raising water levels will only create more areas for feeding. Overall,
beavers will have no adverse impact on the favourable conservation status of
bat species in the area.
Wildcat has been, and probably still is, present in the trial area. Given the
behaviour and habitat requirements for this species it is difficult to envisage
how beavers would have an adverse impact on wildcat. Therefore it is judged
that beavers will have no adverse impact on the favourable conservation
status of wildcat.
4. SCHEDULE 5 SPECIES
There are several species of mammal, protected under Schedule 5 of the
Wildlife and Countryside Act 1981, as amended, present in the trial area; pine
marten, red squirrel and water vole.
Pine marten and red squirrel are very unlikely to be affected by the
presence of beavers The risk of felling a tree that has been occupied by
these species is extremely low. Therefore beaver will have no adverse impact
on these species.
Water vole habitat is protected, rather than the animal itself. The species is
semi-aquatic and any effects of beavers are likely to be neutral or beneficial
by increasing habitat. However habitat is probably not a limiting feature in the
trial area. There will not be any competition for food. Overall there will not be
an adverse impact to water vole.
5. BADGER
Badgers are present in the trial area. They tend to have large territories in
Argyll with more than one sett complex. The setts tend to be on better-
drained ground, e.g. slopes and not in areas that would be susceptible to
flooding by beaver activity. There might be a small loss of foraging area.
However overall there will be no adverse impact to badgers.
6. KNAPDALE NSA
Key characteristics of the NSA are;
• Grained topography from NW-SE
• Heavily wooded glens
• Freshwater and sea lochs
• Mosaic of habitats and enclosed landscapes
• Tightly grained and forested hills
The western part of the trial area is within the NSA. The effects of the beavers
will be extremely localised within their territories. The main landscape effects
will be the local removal of trees and shrubs, that will regenerate, and creation
of wetland/flooded areas. None of these activities will have an adverse impact
on the integrity of the NSA.
7. SNH RECOMMENDATIONS
The Scottish Government may wish to use this recommendation, if judged
appropriate, as conditions in any licence provided to RZSS/SWT.
a) Brachytron pratense to be monitored within the SSSI and the trial site
as a whole. Calopteryx virgo should be monitored along specific
sections of enclosed and open burns. This can be done through the
monitoring programme for the project.
Other recommendations relevant to these natural heritage interests are
already addressed through SNH’s appraisal of the proposal in relation to
possible effects on Taynish and Knapdale Woods SAC and Knapdale Lochs
SPA.
