Comeback Species✓✓ 2 independent sources
Beavers: Europe's million-strong wetland engineers return
~1,200 → 1.5 million+ beavers in Eurasia
Overhunting had reduced the Eurasian beaver to about 1,200 animals by 1900; reintroductions and natural spread have since restored the species across most of its former range, with the population tripling since 1998 alone. Research on England's River Tamar shows beaver dams increase water storage and attenuate storm flows, cutting downstream flood risk while creating wetlands that boost biodiversity — gains now recognized in England's legal protection of the species.
A century ago Eurasian beavers were down to roughly 1,200 animals in scattered refugia. Today the minimum estimate is 1.5 million — and their dams store floodwater and clean water for free.