Beavers

A keystone species is a species which plays a unique and critical role in the way an ecosystem functions, or in the structure and health of a habitat. The presence of keystone species determines the types and numbers of other species found in that environment. Without keystone species, the habitat is dramatically different, usually far less healthy, and in many cases, ceases to exist. An analogy is the keystone in a brick arch. If you remove the keystone then the arch collapses. When beavers were removed from Britain, the habitats they supported collapsed.

Beavers do modify the habitats and landscapes they live in through coppicing, feeding and in some cases damming (beavers living on lakes or large rivers have little need of constructing dams). In the first instance, these changes can markedly alter the appearance of the local environment but all of these modifications have a positive effect on biodiversity. 

Beaver adaptations can bring enormous benefits to other species, including otters, water shrews, water voles, birds, invertebrates especially dragonflies, and breeding fish. In effect, beavers naturally create and maintain diverse habitats. Their dams can hold water in periods of drought, can regulate flooding and improve water quality by holding silt behind dams and catching acidic and agricultural run-off.

Beavers forage close to water with activity usually concentrated within 20m of the water’s edge. Beavers do fell broad-leafed trees and bushes in order to eat the bark during the winter and to construct their lodges. Most trees will be coppiced and will regenerate, which diversifies the surrounding habitat structure. Coppicing has been practiced by foresters throughout history as a method to manage bankside trees. The actions of beavers are very similar meaning the woodlands will be naturally maintained.

Beavers are a species that occasionally require the need for direct management intervention by man, if their activities result in undesirable localised flooding or tree felling. Any occasional localised problems are usually overcome by simple actions, such as overflow piping and electric fencing. Beavers rarely eat conifers, although the odd conifer might be gnawed by an immature animal that has not learned that conifers are unpalatable and that its resin gums up their teeth. They generally do not live in water entirely surrounded by conifers.

Impacts from burrowing, ie collapsed banks, are a factor and have been cited by some anglers.

Evidence from Europe shows that shows that beaver damage is, in the vast majority of cases, small-scale and localised. Beavers are not regarded as pests in Europe and where localised problems have occurred, there are a number of well-established methods in place. These include the removal of dams, the introduction of overflow piping, or the installation of fencing (as one does for deer and rabbits).

In general terms, beavers can actually help reduce the risk of flooding lower down in river systems by building dams and moderating water flow. The modifications made to the streams can raise the water table locally, creating wetland areas to the benefit of biodiversity. Evidence from elsewhere in Europe shows that instances of beaver dams creating undesirable flooding are uncommon, localised and usually small-scale. In these situations dams are simply removed or pipes (‘beaver deceivers’) are placed through them to manage water levels.

It is important to differentiate between the storage of water by beavers in river headwaters, and the impact of beavers on low lying land. In some places, culverts and drainage systems, some of which are critical to reducing flood risk, need to be kept clear of beaver debris

No. Beavers are completely vegetarian. Beavers eat woody plants and bark, aquatic plants, grasses and shrubs.

Beaver activities may have both positive and negative impacts on different fish species. Understanding the overall impact is complex. Beaver dams may act as barriers to migratory species such as salmon in some years and conditions, and cause localised siltation upstream of dams affecting spawning habitat. On the other hand, positive impacts may include an increase in habitat for fish rearing and overwintering, an increase in refuge areas during high and low flow periods and an increase in aquatic invertebrate prey species. Read more about the potential impact on fish by the Scottish Wildlife Trust.

Beavers have a definite preference for certain trees. Preferred tree species include alder, aspen, apple, birch, cherry, cottonwood, poplar and willow. Aspen/poplar and apple are their favourite. If the supply of their preferred trees is low, they will harvest oaks and some maples.

Conifers such as pines, hemlocks, etc. are their least favourite. Sometime they will girdle (remove the bark around the entire base) of conifers for an unknown reason. One possibility is to obtain a much needed dietary nutrient.

Research suggests that ponds and water pools created from beaver dams can have marked benefits on local water quality. Dams are usually only built on small streams, less than 3 metres wide, and these can moderate the detrimental effect of irregular flow. The modifications can also raise the water table locally creating wetland areas to the benefit of biodiversity.

The ponds can help to neutralise acidic run-off, act as sinks for pollutants and increase the self-purification of a watercourse. They can form considerable sediment traps, reducing very strongly erosive runoff and particulate loads in downstream water.

Beavers can carry host-specific parasites not currently present in Britain, though these are not known to infect or harm other species of wildlife,  livestock or humans. Other parasites carried by beaver are already present in British wildlife, livestock and humans and these other sources of infection pose a more significant risk to water contamination than beavers.

Beavers live in burrows dug into river and pond banks. They sometimes live in lodges built out of sticks and mud. They are mostly nocturnal (they are active at night). They can be seen emerging or returning to their lodges at dusk and dawn, times when they are actively feeding, grooming and patrolling their territories

Beaver reintroduction in Great Britain is a devolved matter. As such, the status of beavers in Scotland, England and Wales is devolved to each respective government and reintroduction is at differing stages across these nations.

There currently is no known evidence of beavers ever having been present in Northern Ireland (or the Republic of Ireland). As such, no beaver introduction projects are due to take place there.

ENGLAND: The River Otter Beaver Trial is a licenced five year reintroduction trial taking place in Devon. This is due to conclude in 2020 and, following this, the UK government is due to make a decision upon the future of beavers in England. There are also a number of fenced projects across the country, including in Cornwall, Yorkshire and Essex amongst others. At present, a licence is required for a beaver project.  

SCOTLAND: As of May 2019, the Eurasian beaver is now protected in Scotland as a European Protected Species and the beavers currently present in Scotland will be allowed to expand their range naturally. The Scottish government have developed a Management Framework, details of which are available here.

WALES: Currently beavers are not recognised as resident in Wales and there are no officially recognised beaver reintroduction trials. There are attempts being made to establish a trial, most notably by the Welsh Beaver Project. 

Species reintroductions, including that of beavers and ‘wildling’ approaches in general terms all fall under a bigger ambition towards delivering what we now refer to as nature based solutions - activities that work with and enhance nature to help address societal challenges, which are grounded in the principle that healthy natural and in many cases managed ecosystems produce a diverse range of services on which we all depend - as well as enhance our well-being and addressing drastic declines in biodiversity.  As well as being in a state of ecological emergency, we are also in a time of climate crisis, and we believe that nature based solutions are of vital importance in our fight on both fronts.  Sea level rise and water management in a time of climate change is inevitably the biggest challenge for the county moving forwards, particularly given Somerset’s low-lying situation.

As a Trust, as part of our new 10 year strategy development, we are exploring a whole range of nature based solutions - over and above those that our own nature reserves are already delivering - to support our work to create a comprehensive and functioning nature recovery network across the county, and as part of a pathway to providing a more holistic approach to improving biodiversity (and bioabundance) and climate adaptation. Beaver reintroduction will be just one part of a much bigger shift in our approach. There is now much evidence to demonstrate that as a natural ‘ecosystem engineer’ beavers can deliver multiple positive benefits for biodiversity, alongside alleviating the impacts of climate change, flooding, droughts and pollution, so the reintroduction of this keystone species will be seriously considered as part of a suite of solutions that will we be delivering in Somerset moving forward. 

The Wildlife Trust’s successful beaver trials have focussed on ensuring that all beaver projects on balance should provide significant benefits in order to go ahead.  As landowners ourselves we are very aware that beaver integration into heavily modified landscapes, such as those that exist in Somerset is complex, and has the potential to create challenges for land managers.  A range of management actions and techniques will be needed, and we feel that the way forward is to work in open partnership with all stakeholders to resolve potential conflicts. 

With any beaver project in the county we would establish volunteer stakeholder groups to help put in place a management framework that ensures that beavers and people can co-exist successfully in a productive landscape.  The stakeholder beaver management group  would also provide training and advice to landowners and volunteers to support any reintroduction, so they are for example able to quickly mitigate any minor issues such as small localised flooding which can occur - easily resolved by either removing dams in problematic places, or modifying them with ‘beaver pipes’.  You can read more about how this might work by reading Devon’s Beaver Strategy Management Framework here and more about their 5 year beaver trial here. Information on all of the Wildlife Trust beaver trials can be found here. Whilst we have seen a shift in landowner’s perception of beavers, we want to go further in educating people about the benefits that beavers bring as oppose to propagating the polarisation that exists around what are potentially natural hard workers in our fight against climate change.

We do feel that beaver populations, particularly in upper catchment areas, can work positively to support water control lower down the catchment by taking significant pressure off those lower catchments by holding water higher up. This slows the flow of water, which will reduce the impacts of flooding from the severe weather events we are experiencing more of now due to climate change. Through their behaviours and management of habitats beavers have also been shown to  improve water quality along the way, enrich biodiversity and help improve the health of soils in land in lower lying areas.  Part of our role is to engage with people across the county and help them understand that they can be hugely positive for the wider landscape, and identify where possible conflicts could occur and put in place a framework to manage those conflicts through the volunteer beaver management group.

Beavers populations spread very slowly. They are shy and keep a low profile and in many areas they can go for a long period before their activity is noticed.   They are very territorial and this regulates their populations - some even kill rival beavers if they stray on their patch.  They only breed once a year and have an average of three kits which are vulnerable to predation. Their numbers don’t extend in a prolific manner. And once they are present, they do not move far from rivers and streams so their activity is largely restricted to approximately 30m away from their water source.