REINTRODUCING BEAVERS TO ENGLAND Digest of a report The by sdsdfqw21

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									 REINTRODUCING BEAVERS TO ENGLAND
      Digest of a report The feasibility and
acceptability of reintroducing the European
                          beaver to England

 Commissioned by Natural England and the People’s Trust for
                                     Endangered Species
                              Why commission a feasibility study?                                                                                                  Why consider reintroducing beavers?
                              Natural England and People’s Trust for Endangered                                                                                    Beavers were a natural part of the British countryside
                              Species jointly commissioned this report.                                                                                            until driven to extinction by humans hunting them
                                                                                                                                                                   for their fur, food and the medicinal properties of their
                              Natural England commissioned this report for two main                                                                                scent glands. They mostly died out in the sixteenth
                              purposes:                                                                                                                            century although there is some evidence that a few
                              •   to help Natural England, as the lead delivery body                                                                               may have hung on until the eighteenth century in
                                  for the England Biodiversity Strategy, develop a                                                                                 northern England. By the 1900s, beavers had been lost
                                  view on the feasibility and desirability of beaver                                                                               completely from large parts of their native range across
                                  reintroductions in England and what contribution                                                                                 Europe with numbers estimated as low as 1 200.
                                  beavers might make to national habitat restoration                                                                                 Since then numbers have recovered in many other
                                  targets. At the time of the publication of this report,                                                                          European countries through regulation of hunting,
                                  Natural England’s Board has not yet considered its                                                                               translocations, reintroductions as well as naturally.
                                  position on beaver reintroductions.                                                                                              In Britain, the Scottish Wildlife Trust and The Royal
                              •   to help Natural England, as the licensing authority,                                                                             Zoological Society of Scotland have been granted
                                  prepare itself for making a decision when it receives                                                                            permission by the Scottish Government for a trial
                                  a licence application to release beavers into the                                                                                reintroduction of beavers in Knapdale from 2009.
                                  wild in England.                                                                                                                 In Wales, the North Wales Wildlife Trust, is assessing
                                                                                                                       Beavers are strictly herbivorous; they      suitable habitat for a potential reintroduction there.
                                                                                                                       do not eat fish or any other animals.
                               People’s Trust for Endangered Species is a UK                                           In spring and summer they mainly            So far, in England, beavers are only present in a semi-
                                                                                                                       eat aquatic and riparian plants, at
                              conservation charity concerned to ensure a future for                                    other times of the year they depend         captive state in a few wildlife parks and sanctuaries and
                              endangered species throughout the world. It provides                                     heavily on woody species for food,          on private land.
                                                                                                                       such as willow, alder, aspen and birch,
                              practical conservation support through research, grant                                   particularly those that are found in very     There are several reasons why beavers deserve
                                                                                                                       close proximity to the water’s edge.
                              aid and educational programmes. People’s Trust for                                                                                   consideration for reintroduction to England:
                              Endangered Species commissioned this report to inform                                                                                •    Beavers were a native species and were for centuries
                              its own view on the feasibility and desirability of beaver                                                                                a natural part of our countryside. Human activity
                              reintroductions in England when assessing any future                                                                                      was entirely responsible for their disappearance.
                              applications for funding any such reintroduction.                                                                                    •    We have a legal obligation to at least consider
                                                                                                                                                                        reintroduction. As part of our commitment to
                                                                                                                                                                        conservation as an EU Member State, the UK is
                                                                                                                                                                        required to carry out studies on the desirability of
                                                                                                                                                                        reintroducing species that have become extinct.
                                                                                                                                                                   •    Beavers are what is known as a ‘keystone
                              A copy of the full report The feasibility and acceptability
                                                                                                                                                                        species’: their loss has a profound effect on their
                              of reintroducing the European beaver to England can be
                              found at www.naturalengland.org.uk or www.ptes.org. Our                                                                                   surroundings. Beavers are nature’s water engineers,
                              thanks go to the authors of the full report as follows:                                                                                   naturally managing riverbank, wetland and forest
                                                                                                                                                                        habitats and the way those habitats behave.
Cover image laurie campbell




                              J. Gurnell, C.G. Faulkes and E.J. Hare (School of Biological and                                                                     •    Many people find beavers inherently interesting
                              Chemical Sciences, Queen Mary University of London); A.M.                                                                                 such that they have the potential for raising
                              Gurnell, D. Demeritt and S. Nobert (Department of Geography,
                                                                                                                                                                        awareness much more generally about nature
                                                                                                     Terry Whittaker




                              King’s College London); P.W.W. Lurz, M.D.F. Shirley and S.P. Rushton
                              (Centre for Life Sciences Modelling, University of Newcastle-upon-                                                                        conservation.
                              Tyne).
What effects are beavers likely to have                                                                                                          recolonisation under certain climatic conditions, or
on their surroundings?                                                                                                                           cause unfavourable shifts in the structure of a fish
                                                                                                                                                 community. Many of these problems could initially be
Reintroductions of any species can pose benefits and                                                                                             avoided by siting reintroduced beaver populations in
risks and both must be carefully assessed.                                                                                                       areas where flow to adjacent water bodies is unlikely




                                                                                                               Laurie Campbell
                                                                                                                                                 to significantly decrease, preventing the likelihood of
PLANTS                                                                                                                                           fish being unable to pass by. Furthermore, the positive
Beaver dam construction can create extensive, mixed                                                                                              impacts of beaver on fish populations are likely to
wetland habitats that substantially increase the variety                                                                                         increase with the maturity of beaver ponds. Monitoring
of species of herbaceous plants around the water banks.                                                                                          of fish populations following beaver reintroduction
Beavers like to feed on a small number of woody plant                                                                                            is essential and may prove useful in reassuring local
species which encourages other woody species to                                                                                                  fisheries and landowners if positive impacts on
predominate. Beavers naturally coppice trees, a practice                                                                                         commercially important species can be demonstrated.
still emulated today in woodland management. Where
young trees are browsed and felled, shoots develop                                                                                               AMPHIBIANS
from the stumps which rejuvenate the woodland by                                                                                                 The reintroduction of beaver to England is likely to
increasing the number of tree stems and helping to                                                                                               benefit native British amphibians by increasing suitable




                                                                                                               PTES
stabilise the banks of water bodies. Overall, the impact                                                                                         breeding habitat, although in certain parts of the
of beavers on plant diversity is very positive, particularly       ABOVE TOP: the European beaver                                                country this could also benefit non-native species such
                                                                  usually digs burrows in riverbanks in
across a whole landscape.                                       which to nest. However, they cut wood                                            as the American bullfrog.
                                                                 to build dams if the water is not deep
                                                                   enough to cover the entrance to the
INVERTEBRATES                                                  burrow. They will also build lodges from                                          REPTILES
                                                                 wood if burrowing in banks is difficult.
Beavers significantly alter the local invertebrate                                                                                               British reptiles are terrestrial and will not be particularly
                                                                 ABOVE BOTTOM: beavers are able to
population in a predominantly beneficial way by                fell quite large trees. This provides dead
                                                                                                                                                 affected by the reintroduction of beavers, although grass
increasing the number and variety of invertebrates. The        wood habitat which is beneficial to many                                          snakes favour damp areas and are good swimmers, so
                                                                                  other species of wildlife.
overall increase in aquatic habitats of all types provides                                                                                       they could benefit from beaver impoundments.
additional foraging habitat for numerous species of
birds, fish, mammals, reptiles and amphibians. Less                                                                                              BIRDS
favourably, beavers do have the potential to harm                                                                                                Beaver ponds provide suitable nesting, foraging,
                                                                     RIGHT: Beavers are able to occupy
endangered freshwater pearl mussels which are a                     and/or modify a wide range of water-
                                                                                                                                                 breeding and roosting habitat for a multitude of
protected species, so some areas might need to be                  marginal environments, but in general                                                             avian species. Bird abundance,
                                                               prime beaver habitat would include easy
protected against beavers for this reason.                          access to grasses, forbs and riparian                                                            production, diversity      and
                                                                  tree species; low flow water depths, at
                                                                 least near their lodge and burrow sites,
                                                                                                                                                                     species richness is generally
FISH                                                           of >0.6m; river channel gradients of less                                                             much greater at beaver-created
                                                                than 0.15 and preferably as low as 0.06
Overall, beavers are likely to have a positive impact on          and ‘soft’ or finer calibre bed and bank                                                           wetlands and very few species
                                                                                                 materials.
fish populations creating foraging habitat and refuge                                                                                                                decrease in abundance with
for a wide variety of species including those that are                                                                                                               the presence of beavers. Beaver
considered commercially important. Increased growth                                                                                                                  reintroduction in England
rates experienced by some fish in beaver pools, along                                                                                                                is likely to benefit most bird
with a tendency for larger species to replace smaller                                                                                                                species and could provide
ones in warm water streams, could provide excellent                                                                                                                  additional foraging habitat for
                                                                                                                                 Duncan Halley




opportunities for anglers. Nevertheless, beaver dams                                                                                                                 conservation priority species,
may restrict fish movement, migration, and prevent                                                                                                                   such as the osprey.
MAMMALS                                                                                                                                               Is there public support for
Beaver habitats attract a large number of mammals and                                                                                                 reintroducing beavers?
could provide food and shelter for many native British
species, including semi-aquatic mammals such as water                                                                                                 There appears to be broad but shallow support from
voles, otters, and water shrews. Any negative impacts                                                                                                 the public at large for wildlife reintroductions. A few
on mammals are most likely to be an indirect result of                                                                                                interest groups are strongly opposed, but the majority
beaver activity, for example by creating habitat which is                                                                                             of organisations interviewed for this project, like the
favoured by introduced pest species, such as American                                                                                                 general public at large, are likely to be cautiously,
mink.                                                                                                                                                 sometimes even enthusiastically, supportive of any
                                                                                                                                                      proposals to reintroduce European beavers to England.
 As with all reintroductions, careful monitoring would                                                                                                  The most commonly perceived benefits of
be required in trial areas but the net result of the                                                                                                  reintroducing beavers were the potential opportunities
presence of beavers is likely to be positive with a                                                                                                   for eco-tourism and various improvements to the




                                                                      Laurie Campbell
substantially higher level of biodiversity.                                                                                                           natural habitat. Where there were concerns, these
                                                                                                                                                      centred on the system for regulating and managing
                                                                                                                                                      introduced populations and on the potential for
                                                                                           ABOVE European beavers consume                             flooding, for damage to woodlands and crops, and their
                                                                                          woody vegetation, grasses, forbs, and
                                                                                        aquatic vegetation. They depend largely
                                                                                                                                                      effects on fish.
                                                                                           on woody food sources in winter, but                         There was consensus among those consulted on four
                                                                                           can spend up to 90% of feeding time
                                                                                          consuming grasses, forbs and aquatic                        things:
                                                                                                          vegetation in summer.
                                                                                                                                                      •    any future reintroduction should be piloted in
                                                                                                                                                           some small, controlled areas, where the impacts
                                                                                          RIGHT TOP: trails and paths such as
                                                                                           this one, made by a mature, resident                            of beavers could be assessed and, if necessary,
                                                                                            beaver are apparently easy to follow
                                                                                        and can be used to set traps along if the
                                                                                                                                                           reversed by their removal
                                                                                                   animals need to be removed.                        •    the legal status and management responsibility for
What does the law say about beavers?                                                                                                                       any pilot introduction must be clear
                                                                                             RIGHT BOTTOM: tree guards, and
                                                                                                                                                      •    there must be extensive public consultation




                                                                                                                                    Laurie Campbell
The UK is obliged through the EU Habitats Directive to consider                            exclusion fences may be used where
the desirability of reintroducing beavers as they are one of a                                necessary to protect specific trees                          early enough in the planning process to have a
                                                                                           or whole areas from potential beaver
number of species listed as requiring action to achieve favourable                                                     damage.                             substantive influence on the details of whether,
conservation status across their former range.                                                                                                             where, when, and how beavers are introduced and
Possession of beavers in England has to be licensed by Natural
England.
                                                                                                                                                           managed
Releasing beavers into the wild is an offence under the Wildlife &                                                                                    •    there must be objective and trustworthy
Countryside Act because the species is not ‘ordinarily resident in                                                                                         information widely available about European
Great Britain’.                                                                                                                                            beavers and their likely impacts on the landscape.
If beavers are released into the wild in England, they would be
considered by the law to be wild animals. But because they are
not living here now, they are not protected by any UK legislation,                                                                                     There were contrasting views on where any pilot
so reintroduced beavers could be disturbed or killed. However,                                                                                        reintroduction would best be located. One view was that
the UK would be obliged to protect beavers if they became                                                                                             beavers should be placed in remote areas away from
established in the wild.
Once protected, the management of the beavers could be
                                                                                                                                                      human populations to reduce the potential for conflict
licensed by Natural England, under various provisions in the                                                                                          between beavers and people. The alternative view was
existing Habitats Regulations. Beaver dams are probably not                                                                                           that beavers ought to be reintroduced to accessible
                                                                                                                                    Phoebe Carter




always protected, as they are not breeding sites or resting places.                                                                                   areas (perhaps floodplains or brownfield landscapes),
However, a licence would be needed to destroy one if it affected a
nearby breeding site or resting place.
                                                                                                                                                      so that the ecological benefits can be easily witnessed
                                                                                            Duncan Halley
and their economic potential harnessed.                                                                                                                         yearlings born the previous year and the young of the
 Certainly any future reintroduction plans would need                                                                                                           current year. A 2km length of river with suitable habitat
to involve extensive public consultation, backed by                                                                                                             should be sufficient to support a colony, where habitat
clear, objective and trustworthy information about                                                                                                              is assessed within 20m of the water’s edge.
the management and likely environmental impacts                                                                                                                  Densities of beaver populations at particular sites vary
of reintroduced beaver. Local public acceptance is                                                                                                              depending on how long the sites have been occupied.
particularly important so that restoration plans and                                                                                                            Population growth may continue for 25 years or more
the licensing approvals on which they depend are not                                                                                                            until all available sites have been occupied. Where data
compromised.                                                                                                                                                    are available, over half of introductions of beavers in
 The ‘success’ of any reintroduction must be judged                                                                                                             Europe have been successful. Failed introductions have
not simply in scientific terms of how well the species                                                                                                          been attributed to release into unsuitable habitat and
is doing in its habitat, but also in terms of how those                                                                                                         too few individuals being released with subsequent
impacts are perceived and understood by the public                                                                                                              poor population growth.
and other stakeholders. Whatever their relationship to                                                                LEFT: beavers often excavate canals        From work in other countries, much is known about
                                                                                                                      to allow more extensive access to the
received scientific opinion, public perceptions of the                                                                riparian zone.                            the habitat requirements of beavers including how
potential impacts of a beaver reintroduction have to be                                                                                                         much river habitat would be required to support a
addressed by any future reintroduction plan.                                                                          BELOW: water levels in beaver ponds       beaver family, the most appropriate width, gradient,
Some of the concerns expressed by the stakeholders consulted, such as worries about the                               reflect the balance between river flow,
interviewed for this study requested more information about European beavers to help them                             precipitation and groundwater seepage     velocity and depth of the river, the composition
                                                                                                                      into the pond versus river flow and
decide upon a formal policy position on the issue.                                                                                                              and profile of the banks, the vegetation required for
What habitat best suits beavers?                                                                                      groundwater seepage out of the pond
                                                                                                                      and surface evaporation.                  food and construction, and appropriate floodplain
                                                                                                                                                                characteristics.
Beavers are able to live in a wide range of wetland
environments, but in general there appear to be four
broad characteristics of prime beaver habitat:
•   they like easy access to grasses, non-woody
    herbaceous plants and riparian tree species,
    especially poplars and willows
•   water at least 60cm deep when at its lowest near
    lodges and burrow sites
•   river channel gradients typical of lowland rivers
•   ‘soft’ or fine bed and bank materials

 Beavers normally live as a family unit or colony of four
or five individuals, consisting of two parental adults, the

 Is it safe to reintroduce beavers?

 There is no evidence that reintroducing beavers into England
 poses any significant public health risk, providing appropriate
 quarantine procedures and health checks are followed. There is
 considerable experience of moving and managing captive beavers
 within England. Importantly, stress should be kept to a minimum
                                                                                                    Terry Whittaker




 during the capture, transportation, quarantine and release of
 beavers, to minimise disease risks that can be aggravated by a
 weakened immune system.
                                                                                                                                                         Where would beavers best be




                                                                                                                                      Duncan Halley
  Potential candidate release sites should:
•    have sympathetic land managers and conservation                                                                                                     introduced in England?
     designations if present
•    be good beaver habitat (low-moderate flows,                                                                                                         Many, if not most, of England’s rivers could provide
     presence of aquatic, semi-aquatic vegetation,                                                                                                       suitable habitats to support beavers. There are various
     bankside trees and bushes) within wetlands                                                                                                          ways to identify the most advantageous habitats but
     and/or a river system with the potential for the                                                                                                    deciding upon trial sites would require many factors
     beaver population to grow and expand across                                                                                                         to be taken into account, the lie of the land being only
     neighbouring areas within at least a five-year                                                                                                      one.
     period                                                                                                                                               Using GIS (Geographical Information System) mapping
•    be a wetlands/river system with natural barriers to                                                                                                 techniques, maps of woodlands and inland waters have
     unlimited expansion so that containment, control                                                                                                    been created, taking account of appropriate river slopes,
     or removal is achievable if required                                                                                                                to identify suitable beaver habitat. Urban and suburban
•    be located away from urban/suburban areas to
     avoid high levels of interaction with humans                     ABOVE: along with the potential for
•    be a river system with headwater catchments of                    eco-tourism, various improvements
                                                                          to ecosystem services were the
     moderate elevations to assess effectiveness of                   most commonly perceived benefit of
     beaver dams and managing flood risk should dams                                 reintroducing beaver.

     fail
•    have the capacity to use fencing to prevent
     stock infiltrating the bankside habitats, or to
     prevent beavers moving onto agricultural land or
     woodland
•    have the capacity to study changes in animal and
     plant biodiversity before and after reintroduction,
     and to study the beavers
•    be degraded, partially degraded or flood-risk
     habitats to demonstrate potential restoration of
     natural habitat features and the water table, flood
     alleviation and water purification of beavers, beaver
     dams and beaver ponds
•    have the physical capacity to accommodate
     potential ecotourism.
Stakeholder groups consulted:

Anglers’ Conservation Association; Association of Drainage                                                                                               areas were omitted because of potential conflicts with
Authorities; Association of River Trusts; British Association for                                                                                        humans or their activities, and areas that contained a
Shooting and Conservation; British Waterways; Centre for Ecology
& Hydrology; Confederation of Forest Industries; Country Land
                                                                                                                                                         substantial amount of agriculture were omitted because
& Business Association; Campaign to Protection Rural England;                                                Figure 1a. Results of the GIS study of      of potential damage to crops. The most suitable sites for
                                                                                                             beaver habitat suitability, allowing a 3%
Environment Agency; Forestry Commission; Game and Wildlife
                                                                                                             topological slope. Green indicates at
                                                                                                                                                         beaver colonisation were considered to have a total of
Conservation Trust; Kent Wildlife Trust; National Farmers Union;                                             least 2km of suitable river habitat; blue   4 or more kilometres of wooded river, and minimum
National Gamekeepers Organisation; National Trust; Pond                                                      indicates 3km of suitable river habitat;
Conservation; Royal Society for the Protection of Birds; Salmon and                                          and purple indicates 4km of suitable        suitability had between 2 and 3km of wooded river.
                                                                                                             river habitat in each 5km square.
Trout Association; Water UK; Woodland Trust.                                                                                                              A wide range of potential release sites emerges. The
                                                               Figure 1b. Results of the GIS study of
                                                             beaver habitat suitability, allowing a 6%                      designations). Also to consider is the likelihood of any
                                                                 topological slope. Green indicates at
                                                              least 2km of suitable river habitat; blue                     chance of flooding due to the construction of a beaver
                                                               indicates 3km of suitable river habitat;                     dam or, conversely, whether the presence of beavers
                                                                  and purple indicates 4km of suitable
                                                                     river habitat in each 5km square.                      could assist in river restoration and flood avoidance
                                                                                                                            work; either could occur depending on the site chosen.
                                                                                                                            It would also be helpful to know which candidate sites
                                                                                                                            would naturally restrict the dispersal of beavers in the
                                                                                                                            short term.
                                                                                                                             In short, there are numerous factors to consider when
                                                                                                                            considering possible reintroduction sites but there are
                                                                                                                            likely to be suitable places in England.




maps of beaver habitat preference are shown in Figures
1a & 1b. Squares coloured in purple contain the most
habitat suitable for beaver colonisation, although those
coloured blue or green may contain enough habitat to
support small populations.
 The most suitable habitat for beavers according to this
analysis, in the most general sense, is in the Weald of
Kent, the New Forest, and Bodmin Moor in the south;
the Peak District in the west; and the Lake District and
the Forest of Bowland in the north west; along with a
few other locations of less-concentrated suitable
habitat. There are many options and finding appropriate
river systems is not likely to be a limiting factor.
 One limiting factor, however, might be the proximity
of heavily-populated areas. A glance at the maps
indicates that, despite removing urban and suburban
areas, some of the suitable habitat is still near heavily-
populated areas which might count against some of
them.
                                                                                                          Laurie Campbell




 The conservation status of an area is also important.
Candidate release sites would need to be explored
as to their special protection status (SAC or SSSI
What actions would need to be taken                                                                          local management group to oversee and monitor
for a reintroduction to happen?                                                                              the release
                                                                                                         •   pre-emptive management at any candidate site
Firstly, the IUCN has established a set of guidelines on                                                     (eg to protect vulnerable trees and crops)
reintroductions (IUCN 1998), and any reintroduction                                                      •   provision of sufficient funds to carry out the
of beavers to England must comply with the key                                                               reintroduction programme
recommendations made in those guidelines.                                                                •   importation of the beavers and quarantining with
 In addition, the following actions need to be taken                                                         appropriate health checks
into account in any plan to reintroduce beavers into                                                     •   preparation of the site for a soft release: after six
England:                                                                                                     months of quarantine, releasing the beavers and
                                                                                                             monitoring for at least five years
•   production and dissemination of educational                                                          •   widespread publicity locally and nationally of the
    material about beavers, their possible impacts                                                           presence and conservation importance of the
    and management to enable informed public                                                                 return of beavers to England.
    consultation
•   reviewing and, if necessary, amending legislative
    mechanisms to protect and manage beaver
    populations in England                                                                               So is it feasible?
•   clarification of who would be responsible
    for any release and management of                                                                    It is clearly feasible to reintroduce beavers into
    beavers and grant-aid schemes established                                                            England with many consequent benefits, not least the
    to offset any financial costs of management and                                                      potential for beavers to assist with river and floodplain
    mitigation                                                      BELOW: the selection of a            restoration. The success of reintroductions elsewhere
•   selection of candidate release sites for detailed       canditate release site will depend           in Europe has demonstrated the feasibility of putting
                                                           on local consultation as well as the
    habitat analysis, population modelling and a risk      environmental requirements of the             in place measures to deal with any possible adverse
                                                                                      beavers.
    analysis of human-beaver interaction                                                                 consequences. However any further consideration of
•   thorough local consultation                                                                          candidate sites needs to be made in the context of the




                                                                                                  PTES
    exercise of stakeholders to                                                                          necessary actions described above.
    gain their approval, including
    landowners and the general                                                                           For more detail on the issues explored in this digest
    public, at any candidate site to                                                                     please refer to the full report referenced in the box on
    explore the costs and benefits                                                                       the first page.
    of such a reintroduction
•   consideration of the costs,
    timing and source of beavers
    and their quarantine and the
    necessary licences and permits
    to carry out the importation,
    quarantine and release of
    beavers secured
•   properly costed research and
    monitoring proposals at any
    site and establishment of a
               Beavers belong to the rodent family Castoridae, of which there are two species,
  fact         one American, one European. Both species had close brushes with extinction
file           in the early 19th century but are now out of danger, thanks to intensive
               conservation efforts on both continents.




                                                                                                               Laurie Campbell
Common name european Beaver
SCientifiC name Castor fiber
HaBitat: semi-aquatic living in rivers, streams, ditches, lakes and wetland areas.
SiZe: large for a rodent, 15 – 38 kg in weight, 122 – 137 cm long.
DiStRiBUtion: presently extinct in UK; returning to much of its former range across Europe.
ReaSon foR DeCLine: human activity – hunting for fur, food and medicinal properties.
famiLY Life: live in small family groups of an adult male and female, and one to three young within a
territory of 1-13km of river or lake bank.

Diet: strictly herbivorous; do not eat fish or any other animals. In spring and summer they eat aquatic
and riverbank plants, at other times of the year they depend heavily on bark for food, such as willow.
Can fell trees leaving characteristic feeding signs. In autumn, they transport felled wood to store close to
their riverbank burrows or lodges made of cut wood, to provide winter food. Sometimes build dams of
tree trunks, branches, twigs, earth, mud and stones in order to raise and stabilise the local water level,
providing deeper water to cover lodge entrances, support the transport of food, and extend the position of
the water’s edge. May also dig canals to extend their waterside foraging area.

eCoSYStem effeCtS: often called ‘ecosystem engineers’ because of their ability to build, dams and
canals, create ponds and fell trees.

								
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