Photo
© Niall Benvie
The European beaver was an important part
of the native fauna of the Caledonian Forest. Hunted to extinction
by the 16th century, it is now poised to become the first of
our extirpated mammals to be reintroduced.
Distribution
The European beaver was originally distributed
throughout most of Europe and northern Asia, from Scotland to
eastern Siberia. Within this range, beavers occurred along wooded
streams and rivers, and in small ponds and lakes surrounded
by trees. However, by the end of the 19th century beaver populations
in Europe had been reduced to a few isolated sites in the Elbe
River basin in Germany, the Rhône River basin in France, and
southern Norway. Other small populations survived in Belarus,
Russia and Mongolia. The main cause of this dramatic reduction
in beaver numbers was hunting for their pelts, meat and castoreum
(a secretion from their scent glands), although habitat loss
was also a contributory factor.
Since the 1920s, beaver reintroductions have
taken place in thirteen European countries, and by the early
1990s beaver numbers in Europe were estimated to have recovered
to about 250,000. However, the International Union for the Conservation
of Nature (IUCN) still classifies the beaver as `Vulnerable',
meaning that it could become in danger of extinction in the
future. (Note: the North American beaver, Castor canadensis,
is a different species, and has always been confined to Canada
and the USA.)
Distribution
in Scotland
Based on palaeontological and archaeological
remains and historical evidence, scientists have concluded that
the beaver was widely distributed throughout mainland Scotland,
with bones having been discovered from Dumfriesshire in the
south to Caithness and Sutherland in the north, as well as in
Perthshire and Moray.
The exact date of the beaver's disappearance
from Scotland is unknown, but it was certainly still present
in the 12th century, when excise duty was collected on the export
of its pelt. Written records indicate that it may have survived
in small numbers at a few locations until the 16th century.
Photo
© Niall Benvie
Physical
characteristics and behaviour
The beaver is the largest rodent native to
Europe, with adults weighing 18-20 kg., and exceptionally, up
to 29 kg. Head and body length is between 70-100 cm., while
the tail is from 30-40 cm. long. The beaver is mainly nocturnal
and is highly adapted to its semi-aquatic lifestyle, with sleek
waterproof fur, a distinctive, hairless, flattened tail and
webbed hind feet, which it uses for propulsion in the water.
The beaver also uses its tail to slap the water surface when
it is alarmed, before diving underwater and swimming away; it
can remain submerged for up to fifteen minutes. The long claws
on its front feet are adapted for digging, and the beaver is
highly dexterous, being able to hold small objects between its
toes while feeding. Beavers generally live for 7-8 years, but
have been known to live for up to 25 years. With most of their
predators, such as the wolf (Canis lupus), brown bear
(Ursus arctos), lynx (Felis lynx) and wolverine
(Gulo gulo), now very rare or extirpated from their former
range, most beaver mortalities are caused by humans, through
poaching, road accidents and entanglement in nets.
Beavers live in small family groups, usually
consisting of 3-5 individuals and comprising an adult pair,
kits, yearlings and one or more sub-adults. Females normally
reach reproductive age at three years, and an adult pair produce
one litter per year, consisting of 2-3 kits. A family group
will have a territory which averages 3.6 km. of river bank,
but can be from 0.5-13 km., depending on the availability of
food. Territories are scent marked with castoreum, a secretion
from the anal gland beneath the tail, which has long been known
to have medicinal properties. (Castoreum contains salicylic
acid, the main active ingredient in aspirin, and the hunting
pressure for castoreum was one of the main causes for the beaver's
historical decline in numbers.)
The European beaver prefers burrows in river
banks as a nesting place, but it will build lodges of piled
logs where burrowing is not possible. It builds fewer dams than
the North American beaver, and it does so generally in shallow
streams to maintain water levels above the entrance to its burrow.
Dams are built of tree trunks, branches and mud, and are about
one metre in height and rarely longer than fifteen metres. They
are usually breached by flood waters each year, and do not normally
pose any obstacle to the movements of fish such as brown trout
and salmon.
The beaver is entirely herbivorous, and in
the late spring and summer eats mainly aquatic plants, grasses,
ferns and shrubs. At other times of the year, woody species
form the major part of its diet, with aspen
(Populus tremula), birch
(Betula spp.), oak (Quercus spp.) and rowan (Sorbus
aucuparia) being particularly favoured, although it will
also eat willow (Salix spp.), alder (Alnus glutinosa)
and ash (Fraxinus excelsior). Conifers are rarely touched.
Feeding generally takes place within ten metres of the water's
edge, and the beaver will rarely travel more than 100 metres
from water. It prefers trees with a diameter of less than ten
cm., but it is capable of felling trees up to one metre in diameter.
In areas with harsh winters, the beaver will transport woody
material to its burrow or lodge, storing it there so it can
feed when the water is frozen. In common with other rodents,
the beaver's incisors grow constantly during its life, and it
needs to use these teeth regularly to prevent them from becoming
too long. For this reason the beaver will sometimes gnaw trees
without actually felling and using them.
Ecological
relationships of the European beaver
Beavers are notable amongst mammals for their
ability to alter their surroundings to make them more suitable
as their habitat, mainly through the construction of dams, canals
etc. These activities determine many of the relationships which
beavers have with the flora and fauna where they live.
The felling of trees obviously has an effect
on the riverside forest, but this rarely results in deforestation
of the riparian zone. Their effect on many of the deciduous
trees they fell is akin to a natural coppicing process - species
such as oak, rowan and willow will send up new shoots from the
stump of a felled tree, whilst aspen will also regrow, through
its reproduction is by root suckers, or ramets. The presence
of beavers therefore tends to encourage the production of young
shoots or trees in many instances. Although flooding caused
by dams can result in trees being drowned, it has also been
postulated that beavers historically helped the spread of alder
in Britain, by creating suitable habitat for these water-loving
trees to grow in.
The ponds created by beaver dams favour the
growth of aquatic vegetation and also result in population increases
of invertebrate species. This in turn provides an enhanced food
source for fish, amphibians and birds, which also benefits predators
higher up the food chain such as otters (Lutra lutra)
and grey herons (Ardea cinerea), which eat the fish.
Otters are known to use beaver burrows and lodges, as do water
voles (Arvicola terrestris), while several species of
birds, including mallard (Anas platyrhynchos), teal (Anas
crecca) and goldeneye (Bucephala clangula) nest on
beaver ponds.
In North America, the beaver is considered
a keystone species (see Principles
of Ecological restoration page) in river and pond ecosystems,
and it is likely that the beaver would fulfil a similar vital
ecological role here. After an absence of about 500 years, the
proposed return of the European beaver to Scotland will mark
a major and significant step forward for the restoration of
our degraded and fragmented ecosystems.
...
During the first half of 1998, Scottish Natural
Heritage ran a public consultation process, asking the general
public (and those living in Scotland in particular) whether
they were in favour of beaver reintroductions in specific and
limited areas of the Highlands of Scotland and, if so, whether
they were in favour of this happening in the next two years.
Below is Trees for Life's detailed response to this consultation
process.
Response from Trees for Life
to the public consultation (1998) about
a beaver reintroduction to Scotland
Summary
Trees for Life strongly supports the recommendation
from Scottish Natural Heritage that European beavers be reintroduced
to Scotland, and that such a reintroduction should take place
within the next three years.
Furthermore, we strongly urge that the beaver
reintroduction be accompanied by a specific, focussed programme
to achieve a substantial expansion of riparian woodland ecosystems,
in order to ensure the long-term viability of a reintroduced
beaver population.
Details
of our response supporting the proposed reintroduction
1. Beavers play an important role in riparian
ecosystems, and their extirpation in Scotland is a significant
factor in the historical depletion of the country's natural
biological diversity. From an ecological perspective, we believe
that the reintroduction of beavers is essential to return our
rivers to an optimum state of health again. Their return will
have benefits for a wide range of other species, including fish
populations and mammals such as water voles and otters. In North
America, beavers are considered to be `keystone species' in
conservation biology terms, and we believe that European beavers
were originally of similar importance in riparian ecosystems
in Scotland.
2. Scotland is one of the most biologically-impoverished
countries in Europe, with almost all of our large mammals having
been hunted to extinction, and only 1% of our native forest
still surviving. We believe there is a moral and ethical obligation
now to reverse the degradation of the past, wherever possible,
and this is also reflected in the European Community's Species
and Habitats directive, where the UK has an obligation to consider
reintroducing extirpated species of wildlife. Of all our extirpated
mammal species, the European beaver is perhaps the simplest
and least problematical in terms of a reintroduction, and as
such it provides an ideal first step in the direction of reinstating
our missing species of fauna, and thereby returning our country
to an improved state of ecological health.
3. Since the 1920s, beaver reintroductions
have taken place in 13 other European countries, without major
problems or serious conflicts with other land uses. As a result,
viable beaver populations have been reestablished in every country
concerned, except possibly the Netherlands (where the reintroduction
is too recent to evaluate fully) and Switzerland (where the
numbers are small, although they had doubled between the time
of the first reintroduction, in 1956, and 1993)1.
As beavers have been proven to thrive in European
countries such as France and Germany, which are more densely-populated
and cultivated than Scotland, we believe that the successful
results obtained on the continent will be repeated here, if
a carefully planned and monitored beaver reintroduction is carried
out. However, beyond that, considerable experience has been
gained from those previous reintroduction programmes, and this
will be of direct benefit to a Scottish reintroduction, thereby
enabling it to have the best chance of success.
4. Trees for Life's Executive Director, Alan
Watson Featherstone, was one of the participants in February
1996 in a study tour to a beaver reintroduction site in Brittany,
France. The beavers there live in a mainly agricultural landscape,
and through site visits and meetings with local farmers etc,
the tour participants were able to ascertain that the beavers
caused very few problems. The participants observed a small
amount of damage to trees in a conifer plantation, which in
terms of the overall size of the plantation would best be described
as trivial, and also learned of a problem when beavers had blocked
a culvert under a road, causing temporary flooding. Beaver dams
and lodges were also observed, with the former being small in
height and breached by water flows at the time of the tour.
Conversations with local people and the scientists monitoring
the beavers confirmed that the dams did not impede the movements
of brown trout in the river.
The participants were left at the end of the
tour with no doubt that European beavers could be successfully
reintroduced to Scotland, and this first-hand experience forms
an important underpinning of our support for the current proposal
from SNH.
5. As beavers are entirely herbivorous and
generally shy mammals, they pose no threat to people, or to
economically important stocks of animals or fish through predation.
In the unlikely event that a reintroduced population of beavers
were to cause serious problems of some unforeseen sort, their
specific riparian habitat requirements and relatively small
home territories would make them easy to trap and remove. In
other words, a beaver reintroduction would be readily controllable
and even reversible, if it were to go wrong (although we know
of no evidence to suggest that this would be the case).
6. While concerns have been raised about the
possible negative effects of beavers on fish populations, such
as brown trout and Atlantic salmon, in practice these concerns
are not sustained out by the evidence from other beaver reintroduction
sites. During the beaver tour to Brittany referred to in section
4 above, the participants learned first-hand that the beavers
there pose no problems for brown trout, and indeed are considered
beneficial for trout fisheries 2.
Although the location visited in Brittany did
not contain interacting populations of beavers and Atlantic
salmon, experience in Norway (where the conditions more closely
resemble Scotland than do those in Brittany) shows that beaver
populations are not considered a problem for salmon stocks there
3.
7. Tourism is a major factor in the Scottish
economy, and worldwide nature-related or eco-tourism is the
fastest growing sector of the tourist industry. Magazines such
as BBC Wildlife are full of advertisements for Nature Holidays
both in the UK and abroad, while the Highland Wildlife Park
at Kincraig, which contains small captive populations of most
of our extirpated mammals (including beavers) receives large
numbers of visitors each year. We believe that the reintroduction
of beavers to Scotland will have a positive effect on tourism
here, with direct financial benefits to the areas where beavers
are reintroduced, and to the country's economy in general.
Recommendation
for a related programme to accompany a beaver reintroduction
In it's research for the proposed beaver reintroduction,
SNH has concluded that the existing riparian woodland habitat
in Scotland could support up to 1,000 beavers. However, this
habitat is widely dispersed and generally does not form large
contiguous sections. Furthermore, the report also indicated
that of 17,000 square kilometres of buffered water and wetland
in Scotland, only 4% (771 square kilometres) contained broadleaf
riparian woodland 4.
This small percentage reflects the widespread
loss of native forest which has occurred in Scotland, and we
believe that for a beaver reintroduction to be successful in
the long term, it will have to be accompanied by a concerted
programme of riparian woodland expansion, to provide adequate
habitat for a genetically-sustainable population of beavers.
Whilst beavers reintroduced in the next 3 years to the sites
identified by SNH as potentially suitable should be able to
thrive there, the viability of a Scottish beaver population
in the long term will depend on a sufficiently large interbreeding
pool of individuals being maintained. Given the fragmentary
and widely dispersed state of the suitable habitat at present,
this is not likely to be achieved without a significant increase
in riparian woodland (for example, if beavers were to be reintroduced
to the Tay area and the Ness area, these widely separated populations
would be unable to interbreed).
Thus, we strongly advocate that a beaver reintroduction
be accompanied by a special programme to ensure that the extent
of riparian broadleaf woodland in Scotland is substantially
increased, with particular emphasis being placed on the areas
targeted for beaver reintroductions. Such a programme should
focus on linking up existing fragmented sections of riparian
woodland to create larger contiguous expanses, and re-establishing
some riparian woodland in areas where it is presently completely
absent. The programme should have targets set for the riparian
woodland cover to be expanded from the present figure of 4%
to say 15% or 20% over the next 10 years, and increasing again
beyond that. Emphasis should also be placed on tree species
such as aspen, which are favoured by beavers. Because of its
relative inability to reproduce by seed, aspen is one of the
tree species which has suffered most from historical deforestation
in Scotland, and is therefore already in need of assistance
to ensure its regeneration (Trees for Life has been running
a successful aspen propagation programme in the Glen Affric
area for several years now). The reintroduction of the European
beaver therefore provides an ideal opportunity for the establishment
of a concerted programme of riparian woodland expansion, and
for the regeneration of important species such as aspen, which
are currently under-represented in Scotland's native forests.
Such a programme should be facilitated by a
series of incentives, both from SNH itself as part of the beaver
reintroduction scheme, and in conjunction with the Forestry
Authority's Woodland Grant Scheme (WGS), where special measures
could be added to specifically encourage riparian woodland restoration
and expansion, and it make it more cost effective for landowners
to implement such schemes. Such a programme would not only benefit
the return of the beaver, but also, in and of itself, would
make a significant contribution to the restoration of Scotland's
biological heritage through expanding the area of native riparian
woodland and all its associated species of flora and fauna.
NB: We do not see this recommendation as one
which should delay the reintroduction of the beaver, but rather
it should proceed concurrently with the reintroduction, in an
integrated coherent strategy.
References:
1. MacDonald, D. W. et al (1995) Reintroducing
the European Beaver to Britain: nostalgic meddling or restoring
biodiversity? Mammal Review, 25, 161-199
2. Jones, P. (1996) A preliminary assessment
of the possible impacts of reintroduced European beavers Castor
fiber on freshwater salmon fisheries in the UK A report
to the Atlantic Salmon Trust on the "Brittany Beaver Tour"
21-24 February 1996 3. Jonsson, Prof. B (1995) Norwegian experience
with beavers in salmon rivers Personal communication
4. Webb, A., French, D.D. and Flitsch, A.C.C.
(1997) Identification and assessment of possible beaver sites
i n Scotland Scottish Natural Heritage Research, Survey and
Monitoring Report No. 94.
Latest
reintroduction news
Scottish Natural Heritage (SNH) conducted a
public consultation process during the first half of 1998 in
the UK and particularly in Scotland to gauge public support
for the reintroduction of the European beaver. Though the final
results and report of that exercise are yet to be published,
initial response showed an overwhelming public support for the
beaver's return. SNH have now approved in principle a five year
trial project, due to begin in 2002, whereby up to 50 beavers
will be brought from Norway and radio-tagged before release
so that their impact on the environment can be monitored.
A big thank you to all our supporters who contributed
their views to the public consultation!
