International beaver day blog by wildlife assistant Carys

Once hunted to extinction in the United Kingdom for their pelt and castoreum, Eurasian beaver (Castor fiber) numbers are now slowly increasing after reintroductions into wetland riparian habitats. The first licensed reintroduction in Scotland took place in 2009, in Knapdale, Argyll and Bute; only 15 minutes away from my grandparents town, and in 2012, during the summer holidays from my ecological science degree, I was lucky enough to be given the opportunity to volunteer with the beaver reintroduction team!

Thanks so much to Scottish Wild Beaver Group for letting us borrow these amazing photos.

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Credit to Scottish Wild Beaver Group

Beavers have always fascinated me with their complex building skills, their unique split toe nail they use as a grooming tool, and the surprisingly loud smack of their flattened tail hitting the water as a warning call in response to a threat! During my time at the reintroduction, I was allowed to assist the team during night-time behavioural observations from shore line and on boat, see routine trapping and health checking be carried out, and assist in educational guided walks of the beaver site. During these few months, I learnt a lot about these fascinating rodents, the amazing work they do to engineer their environment and the multitude of benefits they bring to the area they inhabit and to us living downstream!

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Credit to Scottish Wild Beaver Group

Beavers are regarded as ‘ecosystem engineers’ as they modify their environment, resulting in a multitude of ecological and hydrological consequences. The beaver’s main attributes as an ecosystem engineer are the coppicing and felling of trees, and most notably, the creation of dams, resulting in flooding and a subsequent increase in wetland area. As beavers are better suited to movement in water than land, they expand wetlands and create adjoining canals to allow easy access to food and building materials, and to avoid predation. Beavers will fell trees and construct damns at an outflow or stream, to hold large volumes of water or reduce the flow of water out the water body, leading to heightened water levels with deeper and slower water than before. This modification of the beaver’s environment in turn has an effect on other species; creating new niches in the habitat which were previously unavailable, increasing species abundance and diversity, thus making them a keystone species. Here are a few benefits the newly reintroduced beaver can bring!

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Credit to Scottish Wild Beaver Group
  • Increased habitat heterogeneity – beavers ‘ecosystem engineering’ behaviours such as damn building, lodge building, tunnel and canal digging, tree felling and coppicing, and herbivory increases the types of habitat in the beaver’s environment and creates more varied habitats. Subsequently, this increases plant and animal biodiversity by creating new environmental niches.
  • Increased plant biodiversity – beavers coppice and fell trees, leading to a reduction in canopy cover and the creation of a more natural woodland composition. This allows more light to reach the canopy floor, and less dominant plant species have the opportunity to grow. Additionally, coppiced trees and shrubs have the opportunity to regenerate and the expansion of wetland areas allows an increase in freshwater flora.
  • Increased animal biodiversity – the expansion of wetland areas and the slow, deep waters held by the dams, will attract many open habitat species such as dragonflies, and will lead to an increase in aquatic and semi-aquatic invertebrates and fish. Deeper, stable water levels even during times of drought provide perfect habitats for otters and breeding birds. New niche habitats and an increase in plant biodiversity will also attract additional animal species such as water voles.
  • Improved water quality locally and downstream – water held by a dam is slower than upstream, thus suspended sediment will fall to the bottom of the water body, improving water quality. Dams will also act as a physical barrier and trap sediment, reducing environmental erosion and improving water quality downstream. Slower water within and released by the dam also results in increased nutrient cycling, further improving water quality. Studies have also found that beaver dams have prevented inorganic fertilisers and other environmental pollutants from flowing downstream
  • Greater carbon sequestration – as wetland habitats sequester carbon (act as ‘carbon sinks’), increased areas of wetland habitat will lead to greater carbon sequestration, helping to mitigate climate change.
  • Reduced risk of flooding downstream – as dams retain water and/or reduce the volume of water released, run off is reduced after heavy rain, reducing the risk of flooding downstream. Moreover, as dams reduce water velocity, any run-off over the dam will be slower, further reducing flood risk.
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Credit to Scottish Wild Beaver Group

Since my time at the beaver reintroduction many years ago, the Scottish Government have voted to allow beavers to stay in Scotland (2016) and more recently, they have been classed as a European Protected Species (2019). We welcome this great news and if anybody reading this ever gets the opportunity to responsibly visit their sites, you will fall in love with them just like me! I know the first thing I am going to do after our current pandemic is over, is book a trip to visit my grandparents and visit the beaver colonies 15 minutes down the road!