We have gathered decades of scientific research from UK, continental Europe and North America to share with people interested in diving deeper into the world beavers.
From beaver biology, ecology and management to their effects on flooding, farming, pollution, carbon, fish and other wildlife, research has been done to help us understand beavers and their wetlands, and to inform how we can co-exist with them.
This list of resources is being constantly amended and updated so check back again soon for more information.
It is well known that beavers engineer ecosystems and in doing so have a range of impacts on ecology, hydrology and geomorphology of aquatic systems, and human society. Prof. Richard Brazier and colleagues from University of Exeter have recently published a very readable overview of these impacts and what they will mean for the future as beavers continue to expand their range throughout the northern hemisphere. A recent paper from the Exeter team looked specifically at how beaver dams attenuate flow by examining records from four sites in Britain with different catchment characteristics (stream orders ranging from 2 to 4; agricultural or forest-dominated). Their findings showed flow attenuation across a range of rainfall conditions with a reduction in average flood flows of up to 60%. Altogether, their data provide compelling evidence that beavers can play a major role in delivering natural flood management in Britain. Recently Annegret Larsen and colleagues have published a very detailed review of the impacts of beavers on hydrology, geomorphology, biogeochemistry, and aquatic and terrestrial ecosystems. These depend to a large extent on the hydro-geomorphic and landscape context and how long beavers maintain ‘disturbance’ at a given site. This is quite a long read but well worthwhile to get an understanding of beaver-environment interactions. Another recent paper by Amanda Ronnquist and Cherie Westbrook explore the diversity in structure and hydrology of beaver dams at different sites in the Rocky Mountains. They provide an interesting classification of dams according to their flow state; this is related to the physical structure of the dams and their landscape setting. Full details and access to these papers can be found in the Beavers and land and water section below.
THE ECONOMIC VALUE OF ECOSYSTEM SERVICES
Beavers provide benefits through the ecosystem services (water purification, moderation of extreme events, habitat and biodiversity provision, nutrient cycling, greenhouse gas sequestration, recreational hunting and fishing, water supply, and non-consumptive recreation) they provide but quantifying and putting a common system of values on these services is no mean feat. It’s a complex area and there are estimates for some services in some areas in the literature. However Stella Thompson and her colleagues have gone a step further and estimated the value of beaver benefits from across the Northern Hemisphere; their findings are presented in a paper recently published in Mammal Review (see Beavers, people and management below). The numbers are large, in terms of millions of USD, for each service from across the range of both North American and Eurasian beavers. Such schemes, but maybe based on estimates at local, regional and national scales, could greatly assist in offsetting the costs to landowners and others resulting from beaver impacts by the ecosystem benefits that beavers provide.
BEAVERS AND FISH
Beaver-fish interactions are an important consideration for the reintroduction of beavers into UK rivers. A recent paper by scientists based at the University of Southampton has compared the effects of beaver modified habitats on brown trout populations in Scotland. They compared two first order streams that flowed into Loch Grant in northern Scotland, one stream had beaver dams, the other did not. Before the beavers modified one of the streams, the two streams were similar in terms of physical features, hydrology and geomorphology. In the modified stream, beavers built dams creating deep pools that increased habitat and food availability for brown trout. As a result, the trout responded positively and were generally larger and more abundant in the beaver stream. This is an important paper being the first to look in detail and beaver-fish relations in a UK context. More details of the publication can be found in the Beavers and Wildlife section below.
BEAVERS ARE NOT A DISEASE RISK
From the time that beavers were first introduced from Europe into various locations in Britain, an understandable concern has been whether they pose any disease or parasite risks to people or native wildlife. A paper published early in 2021 by Roisin Campbell-Palmer and her colleagues largely puts these concerns to rest. They examined live beavers and beaver carcasses from from three areas: Tayside, Knapdale and Devon (with beavers originally coming from either Norway or Germany). They found that all beavers were in good health and did not harbour any non-native disease or parasites of potential concern and generally they revealed low levels of disease and parasite exposure. They conclude that beavers are, “not acting as reservoirs of significant zoonotic disease“. Details and access to the paper can be found in the Beavers health and genetics section below.
SOCIETAL IMPACTS OF BEAVERS
As well as their influence on the ecology, hydrology and geomorphology of rivers, lakes and wetlands, beavers can affect the activities of people who one way or another interact with these aquatics systems. This can lead to benefits such as increased biodiversity, reduced flooding and increased tourism but also to conflict situations which can be especially troubling when beavers move into new areas. With respect to the latter, early engagement with local stakeholders is crucial to minimise conflict escalation, particularly in connection with beaver reintroductions. Roger Auster and colleagues have recently published four papers on these topics based on the River Otter Beaver Trial in Devon, England. This includes a paper on contrasting perspectives about beavers within the angling community and how potential conflicts can be minimised. The go-to handbook for beaver management is by Dr Roisin Campbell-Palmer et al and is full of support for land and river managers based on decades of international experience. Details can be found in the Beavers, people and management section below.
PSYCHOLOGICAL BENEFITS FROM REINTRODUCING BEAVERS
Sam Gandy and Rosalind Watts have written a timely and well worth reading article discussing the potential psychological benefits of reintroducing beavers and restoring biodiversity at a landscape scale, as well as potential negative psychological impacts requiring appropriate mitigation initiatives. The authors say, “Overall psychological benefits of beaver reintroduction likely exceed that of any other single species’ reintroduction or conservation initiative of equivalent cost, and far outweigh the costs of their reintroduction and management.” Details can be found in the Beavers, people and management section below.
BEAVER DAMAGE TO AGRICULTURAL CROPS
Beavers dams can have unacceptable impacts on farmland by blocking culverts and drains, flooding pasture and arable crops or waterlogging fence-lines and tracks. They may also have direct effects by consuming agricultural crops such as maize but an important question is how significant is this financially. A new paper by Mikulka and colleagues (2020) in an agricultural landscape in the Czech Republic explores this in detail. They quantified consumption for a range of different crops over a two-year period, taking into account beaver numbers, distance of crop from the beavers’ burrow, the month of the growing season and the growth stage of the crops. Although the beavers used all the different crops as a food source at different times, the authors concluded, “From an economic point of view, beavers pose no serious problems to farmers as the numbers in open agricultural landscapes remain low. The total financial loss is extremely low, and it considered negligible in comparison to crop damage from other rodents or game species.” The paper can be found in the Beavers, people and management section below.
SMOKEY THE BEAVER
A recent, topical paper on how beavers create wildfire refuge areas in USA has been published by Emily Fairfax and Andrew Whittle, and Ben Goldfarb has written a popular review of this important work in National Geographic. It is another example of the benefits of wetland habitats and rich riparian corridors created by beavers for both humans and wildlife. The full references to these articles can be found in the Beavers and land and water section below.