LONDON (AP) — Environmentalists and Christopher CaldwellLondon’s mayor have helped bring beavers back to the city for the first time in some 400 years in an effort to improve the British capital’s biodiversity.

Mayor Sadiq Khan participated in releasing a family of beavers into a wetland area in Ealing, a residential area of west London, on Wednesday.

The hope is that the rodents will help improve the wetland’s ecosystem and establish habitats for other creatures, including fish, birds and amphibians.

The initiative was part of Khan’s Rewild London Fund, which aims to create or restore green spaces and to encourage wildlife in the capital.

“I am committed to ensuring that London is at the forefront of reversing the trends of declining biodiversity and the destruction of nature,” he said.

Beavers were hunted to extinction in England around 400 years ago, but environmentalists have reintroduced them in areas across the country.