Britain’s most endangered animals and plants have declined by 58 percent since the 1970s, and one in ten is threatened with extinction, according to a recent report .

The U.K. has lost 44 million birds since 1966 and, historically, more large mammals—including wolves, lynx, bears, beavers, boars, moose, bison, and wolverines—than any other European country except Ireland.

Now, red squirrels, wildcats, horseshoe bats, harbor seals, along with numerous birds, butterflies, and beetles are teetering on the cliff-edge of extinction.

Sightings of even the most familiar and beloved creatures, like the hedgehog (Beatrix Potter’s Mrs. Tiggywinkle) and the water vole (Ratty in Wind in the Willows), have become a rarity.

To remedy this catastrophe, Rewilding Britain —a charity set up by a group of leading environmentalists—was launched on July 14.

Its aims are ambitious: To restore ecosystems, reverse the loss of biodiversity, revitalize rural economies, and secure 2.5 million acres of land and 30 percent of the country’s territorial waters for nature by 2115.

The change is already happening. For more than a decade, my husband, Charlie Burrell, an environmentalist and chairman of the Beaver Advisory Committee for England , has been campaigning for the reintroduction of the beaver, a keystone species, important because of the disproportionate effect it has on the ecosystem.

This milestone paves the way for other possible reintroductions of extinct keystone species such as the lynx and, eventually, the wolf.

Out With the Old

The proponents of Rewilding Britain claim that traditional conservation approaches, notably national parks and nature reserves, are patently failing. Isolated oases of nature, they’re susceptible to huge losses in the face of climate change and pollution.

View Images As part of the Knepp rewilding project, a stretch of the heavily engineered River Adur has been restored to a more natural state by restoring its meanders, bringing it closer to the floodplain, softening and breaking up its banks, and putting in woody debris. Simply reintroducing the beaver would have done the job in half the time and at no expense. Photograph by Charlie Burrell

Rewilders say that what’s needed instead is to restore “self-willed” ecological processes—allowing diverse living ecosystems the freedom to function with minimal human intervention.

Connectivity is considered crucial—habitats connected together using corridors such as river valleys and hedgerows and copses in open grassland. These stepping stones allow animals to travel through areas disturbed by human influence and find favorable places for food and shelter.

The rewilding movement has accelerated in Europe in recent decades, with keystone species like bears, beavers and wolves on the rise.

But until now, the U.K. has been slow to catch the zeitgeist.

Rewilding Britain aims to offer advice to those interested in rewilding, highlight examples under way in Britain, and spur a national rewilding movement by raising awareness among various interests: private and public landholders, local communities, farmers, NGOs, government agencies and others.

The spark for Rewilding Britain was environmental campaigner and Guardian columnist George Monbiot ’s 2013 book Feral: Searching for enchantment on the frontiers of rewilding .

“To my surprise, the book took off,” Monbiot says. “It turned out I wasn’t the only one who felt this way. Everywhere I went I was asked the same question: How can we make this happen?”

He hopes that rewilding will change the face of Britain. “One day, if we succeed,” he says, “you’ll be able to enjoy in this country magnificent encounters with wildlife of the kind for which people now travel halfway round the world.”

Return of the Beaver

Charlie and I didn’t have to travel far to that river in Devon, where, standing on the bank, we watched the family of beavers as they fled their traveling boxes and plunged into the water.

View Images Old English longhorns graze beside a lake in a naturalistic grazing project at Knepp Castle, in West Sussex, England. Photograph by Charlie Burrell

We’d love to see beavers back on our own land in West Sussex to restore another dimension of dynamism. In 2001, we abandoned our loss-making farming business and released our 3,500 acres of heavy Weald clay back to nature.

The results have been astonishing : We now have 2 percent of the U.K.’s population of nightingales and have become a breeding hot spot for numerous nationally rare species, including purple emperor butterflies and turtledoves.

Part of our rewilding project has involved an expensive restoration of one-and-a-half miles of the River Adur .

We’ve filled in the drainage canal created in Victorian times and allowed the water to return to its original shallower meanders on the floodplain. This has slowed the flow of the water, restoring the riparian meadows to their natural function as a gigantic sponge. The water is clear and purer than before.

The proliferation of invertebrates in the re-wetted areas has brought in numerous birds like green sandpipers (never seen here before), lapwings, and snipe, as well as bats. We now have 13 of the U.K.’s 17 bat species, most of them endangered.

But here’s the kicker: Beavers alone could have performed this hydrological feat in half the time and at no expense.