Eurasian beavers were extinct in Britain for 400 years until reintroduction began in 2009. Their return is transforming wetland habitats and supporting hundreds of species, demonstrating the power of ecosystem engineering.
Beaver welfare in reintroduction contexts is generally good -- the animals reintroduced to Britain have established territories, bred successfully, and demonstrated natural behaviours. The creation of wetland habitats has clear welfare benefits for the diverse community of species that colonise beaver-modified landscapes. Conflict with farmers over flooding creates management challenges that may involve lethal control in some cases -- this welfare trade-off needs careful management. The long-term welfare of self-sustaining beaver populations in restored wetland habitats is broadly positive.