The National Trust’s wetlands project officer has described the effect of four Eurasian beavers on the ecosystem as astonishing, a year after they were reintroduced into the wild in England for the first time in 400 years.

Beavers were hunted to extinction in England in the 16th century and remained absent until a year ago, when a landmark project announced by the National Trust, Defra and Natural England released two pairs relocated from Scotland into a freshwater lake in the Purbeck Heaths nature reserve in Dorset. Since their release, the beavers have constructed a 35-metre dam, improving local habitats for plants, insects, amphibians, birds and bats. Trail cameras even captured the beavers playing with an otter, while a barn owl, a protected species in the UK, was also seen flying nearby.

The project allows for the release of 10 to 25 adult beavers, with the next release expected to take place this autumn.

• Beavers ‘breathe new life’ into Dorset as dams built and biodiversity returns