As remarkable rewilding efforts help Eurasian beavers reclaim the river systems, a new era of “smart rewilding” is emerging. While these ecosystem engineers are transforming lifeless drainage channels into vibrant wetlands, their success is demanding a new conversation on coexistence.
Rewilding was discussed at this year’s Botstiber Institute of Wildlife Fertility Control (BIWFC) 10th international conference, which took place in Barcelona in April 2026. It featured some of the world’s leading wildlife experts coming together to explore how to best support the enigmatic animal.
Beavers are truly capturing the public’s imagination, with the worldwide release of Disney Pixar’s HOPPERS, once again proving that the beaver is one of our most beloved wild animals. But beneath their cute and characterful exterior they may cause substantial local damage when their engineering collides with human land use. Beavers have a unique ability to build dams, flood fields, gardens, forests, roads and even railways, damaging crops, timber, property and public infrastructure.
Their dams often block culverts and drainage systems, leading to backed‐up water, erosion and, in extreme cases, road or embankment failure. Beavers also fell and girdle trees, including commercial timber and ornamental or fruit trees, killing them and altering woodland structure.
Ecologically, dense dam building can change stream shape, slow flows, increase sedimentation and warm the water, which may harm species adapted to fast, cool, free‐flowing channels, including some aquatic insects and fish. So, what can be done to promote coexistence?
The return of the engineer
After centuries of absence, beavers have returned to much of their historic range. In Germany, populations that began with 120 animals in the 1960s have expanded into several thousand, even recolonising major cities like Berlin. In the UK, a new licensing framework now allows for legal wild releases, recognising beavers as key allies in meeting national biodiversity targets. In Poland, the beaver population rose from 40,000 in 2003 to 137,000 in 2019.
Beaver activity can transform biodiversity. Felling trees, digging canals, and building dams creates “mosaic” habitats that benefit invertebrates, fish, and birds. These wetlands also provide essential ecosystem services:
● Flood Mitigation: Slowing water flow to reduce downstream peaks.
● Climate Resilience: Recharging groundwater and cooling local air temperatures.
● Water Quality: Improving sediment cycles and nutrient retention.
In the UK, Eurasian beavers were introduced to Yorkshire in April 2019 by Forestry England,with a breeding pair released into a 10-hectare secured enclosure in Cropton Forest on the North York Moors. The five-year trial, part of the “Slowing the Flow” project, made national news and tested if beaver-built dams can reduce local flood risks, improve biodiversity, and create new wetland habitats.
The challenge of success
However, conservation success brings responsibility. In the crowded landscapes of Europe and the UK, beaver engineering often intersects with human infrastructure. Issues include the localised flooding of farmland, undermining of riverbanks, and interference with culverts.
In Berlin, a recent study highlighted that while beavers offer immense gains for wellbeing and fire-risk reduction, their presence in highly engineered urban corridors requires active management to prevent damage to transport and to energy networks.
As these challenges grow, the search for humane, science-based management tools has never been more urgent.
Conflicting emotions
Dr. Simon Moesch from Humboldt University of Berlin, now working at Ruhr University Bochum, and Dr. Maximilian Hohm from University of Göttingen conducted a survey of people in Germany in 2021 to examine public attitudes toward beavers.
The results showed that the general public tends to view beavers positively, while people working in forestry and agriculture are more critical. Respondents considered urban parks, nature reserves, and zoos, to be the most suitable habitats for beavers. In contrast, private gardens, forests, and agricultural fields were widely seen as problematic locations for beavers.
Dr. Moesch and Dr. Hohm explained: “Even 60 years after their reintroduction, beavers in Germany are still recognised as both a novelty and a nuisance. Our findings highlight the need for active beaver management and increased public engagement to enable positive coexistence between beavers and humans in Germany. Independently of stakeholder groups, we also found large regional differences. Participants from Bavaria – the German state with the highest beaver densities – viewed beavers more negatively than those from the rest of Germany. Zoos and wildlife parks, as well as urban and nature conservation areas, were considered the most acceptable habitats for beavers, whereas private gardens and cultivated areas were largely not accepted as beaver habitats.”
Balancing biodiversity benefits
In the UK a study from the University of Exeter found specific agricultural damage from beavers, including waterlogged land from obstructed drainage, crop losses in maize and organic potato fields, and damage to riverbanks and flood defenses.
Dr Giovanna Massei, Director of BIWFC Europe and professor of Human-Wildlife Interactions at the University of York in the UK, explained: “This research found that beavers improved water quality, which is so important to British people. The beaver’s dams act as natural filters, trapping sediment and reducing pollutants such as nitrates and phosphates from agricultural runoff. And the animal’s reintroduction has had socio-economic effects, promoting positive wellbeing and a boost to nature lovers.
“But this research also discovered that their numbers can grow rapidly, posing a huge challenge for farmers and the forestry sector. I’m looking forward to learning more about how fertility control can safely limit numbers and control beaver populations.”
A global forum for solutions
While non-lethal tools like ‘beaver deceivers’ (flow-control devices) and tree guards remain vital, researchers are increasingly looking at fertility control as a preventative tool to manage the numbers of beaver populations. Unlike culling, which often faces public opposition and can disrupt social structures, fertility control might be used as an alternative, publicly acceptable tool for beaver population management.
The technology – such as injectable immunocontraceptives already successfully used in many wildlife species such as deer and wild horses is available. By treating a proportion of
females in high-conflict urban areas or constrained catchments, managers can slow growth rate without crashing the population.
Dr Massei said: “Fertility control is not about undermining rewilding; it is about making ambitious nature recovery projects politically and practically possible in densely populated countries by using socially acceptable tools. This is why we wanted to bring people together for our conference. It will be a chance to learn, share best practice and discover new ways to deliver coexistence that works for both people and the broader ecosystem.”
A humane approach
It is a timely moment to talk about fertility control because the science allows a humane way for ecologists to manage numbers and prevent human-beaver conflict escalation.
Dr Massei added: “The return of the beaver is one of Europe’s greatest conservation triumphs. By integrating cutting-edge science from forums like the Botstiber Institute for Wildlife Fertility Control Conference into river-basin planning, Europe can ensure that beaver-rich wetlands remain a net gain for both nature and people.”