Beavers were hunted to extinction in England in the 16th century, so locals were surprised to find a group of the mammals living on Devon's River Otter in 2008. Instead of moving the beavers, the Devon Wildlife Trust monitored the population to see how it would interact with the local environment. Now, as The Guardian reports, the government has deemed the beaver reintroduction program a success, meaning the species now has a permanent home in the country for the first time in centuries.

Though the North American beaver is better known, beavers are also native to Europe. Hunting reduced the Eurasian Beaver population to 1200 specimens by 1900. Their numbers have recovered in the years since, but they're still mainly limited to Scandinavia, Germany, France, Poland, and central Russia.

The beaver group currently living on the River Otter likely originated with either an accidental or unauthorized release. When local authorities discovered the beavers were breeding in 2014, they intended to relocate them to protect the local ecosystem. The Devon Wildlife Trust proposed an alternative: Allow the population to live on the river undisturbed for five years, and only remove them if they were proven to cause harm by the end of the trial.

The beavers did not hurt the environment—they actually added several benefits, according to the five-year study. The population, which now consists of 15 family groups, constructed 28 dams throughout the river system. These dams helped slow water flow during floods and contained water during droughts that would normally dry up riverbeds. The beaver-engineered habitat also allowed an increase in the number of water voles, fish, and amphibians.

When the trial officially ends on August 31, the beavers will become permanent residents of Devon in the eyes of the government. They're concentrated on the River Otter for now, but they're expected to expand beyond it, potentially starting new beaver populations in other parts of England for the first time in modern history.

[h/t The Guardian]