Key Findings of the Trial
Some of the headline findings from the Trial include:
• The River Otter beaver population had increased from two family groups in 2015, to occupy around 13 territories by March 2019. With only 3 mortalities reported and the population dispersing throughout the main stem of the river and some of the other tributaries, the catchment is clearly capable of supporting a healthy, expanding beaver population.
• Public perception surveys conducted of 2,741 people nationally found that 86% supported beaver reintroduction in 2017. This had risen to 90% by 2019.
• Beaver dams are not built in larger rivers or streams. Beaver Dam Capacity (BDC) modelling showed which watercourses were capable of supporting beaver dams, and a snapshot survey conducted in October 2019 found a total of 28 dams across six of the beaver territories. These dams allowed the modelling to be verified, and showed how the dams in larger faster streams were much more dynamic structures as they reached the limit of their viability.
• A sequence of beaver dams constructed upstream of a village at risk of flooding has seen a measurable reduction in peak flows as a result of the dams and wetland created.
• The beavers have also caused significant ecological benefits with increases in water vole populations, as well as wildfowl such as teal and snipe in new wetlands created. One County Wildlife Site has seen an increase in its condition due to the changes in vegetation structure and enhanced water levels.
• Five sites have seen land drainage impacts on agricultural land, with feeding seen on riverside maize in three territories, and dams built specifically to access maize crops in some cases. Small riverside orchards have also experienced beaver feeding, both on windfall apples and the trees themselves. Mitigation techniques have been deployed very successfully where problems have been encountered, but the importance of rapid and pragmatic advice and support for affected landowners is highlighted.
• The ecotourism benefits for some local businesses have been significant, although those who benefit from beaver re-introduction may not always be the same people who bear the costs.
• Detailed health screening of the beavers by zoological specialists throughout the Trial concluded that beavers presented no significant risk to human, livestock or other wildlife health.