Eager Beaver

The journey of an animal from near extinction to rehabilitation.

When Europeans first explored the frosty northern reaches of the Americas, beavers ruled the land.

With a population of four hundred million, beavers boasted numbers that today’s humans of the United States are yet to match. Before humans took over, it was this community that laboured throughout the thick deciduous forests, building an intricate and continental network of dams, ponds, and canals, each of which housed an astonishing menagerie of species.

Of course, there were many humans who lived without taking over from the beavers; people who realised the animals were best left alone to do their work. A Cree creation myth follows a pattern similar to that of Noah’s Ark: a great flood that drowned the world and forced humans and animals to escape on a raft. But the cause of the flood wasn’t a great rain — it was caused by a trickster who tried to catch the Great Beaver, who in revenge let the waters rise and rise until they unleashed a global flood.

What happened in real life was somewhat different. Increasing numbers of humans came over the waters that already existed, carrying with them a few select animals, weapons, and diseases. These newcomers proved disastrous for the local ecosystem, beavers being no exception.

By 1900, only around 100,000 beavers remained. From a population greater than that of the human United States, they were down to less than a fifth of today’s human Wyoming.

It was what one could justifiably call an apocalypse.

Beavers are what are known as keystone species: a species that has a very profound, beneficial, and very large effect on its ecosystem, despite not being the largest or most abundant species there. Trees and grass have a very large impact but are not considered keystone species because the impact is not disproportionate to their size.

Most keystone species are not recognised as such until they are removed from an ecosystem — as happened when Europeans arrived on the American shore.

Unfortunately for the beavers, their thick pelts had become a clothing luxury — particularly the fashionable “beaver hat” which was all the rage in the late 1500s. From 1630 to 1640, around 80,000 beavers were killed annually from the Hudson River and western New York.

In this frozen wilderness of wolves and bears, the beaver pelt became the primary means of exchange, known colloquially as a ‘made beaver’. In 1795, a made beaver bought eight knives, a gun, or a kettle, depending on if you felt like cooking or killing.

What they didn’t realise was that, over time, this process would make the wilderness a little more wild — and much more dry.

When it comes to beavers controlling water, the Cree were not wrong. A more recent demonstration of the power of the beaver lies in the story of Jay Wilde.

In 1995, Wilde started work on the family ranch of his childhood, high up in Idaho’s Rocky Mountains. Like most rural folk, he has a talent for simplicity: ‘Cows need two things’, he said. ‘Something to eat and something to drink.’

The problem was, he had neither.

For years Wilde battled, but Birch Creek, where he had once fished as a child, and that used to supply his family farm, continued to dry up. Then one fortuitous morning, while sipping his coffee, he got it.

“Beavers!” his mind exclaimed. “That’s what’s missing!”

After a few unsuccessful attempts, Wilde read about Beaver Dam Analogues: a recent innovation created to prepare a landscape for beaver reintroduction. Built by hand using mud, cobble, and root wads, they are a crude imitation of a beaver’s dam — but they do the job.

Beaver Dam Analogues give the animals a head start, like a pre-furnished home. And for Jay, they were a roaring success.

By autumn 2019, Birch Creek boasted 149 dams, transforming the dreadful dribble back into the stream Wilde had known as a child: flowing forty-two days longer than usual. As Wilde himself put it, with his trademark simplicity, “When you see the results, it’s almost like magic. It makes the effort worthwhile.”

What exactly do beavers do that gives them such power over water? A lot of it centres around their dam-making.

Beavers make their dams by trimming and chopping trees from the sides of rivers. This alters the canopy height, leading to changes in shade, temperature and ultimately food sources available to the fish — a significant boon for struggling salmonids. The changes also help birds, bats, otters, and pine martens due to plant variability and deadwood abundance.

In particular, the willow warbler Phylloscopuis trochilus and the chiffchaff Phylloscopus collybita (named onomatopoeically for its simple song) both enjoy open low canopy woodland. The dense scrub created by beaver activity has proven a great place for their nesting.

Despite beavers having lived in Europe for millennia, there’s a common conception that these dams stop fish from migrating upstream — but beaver dams aren’t as robust as concrete carbuncles. When the water flows fast; fish, such as brown trout, have an opportunity to migrate over the dams. many having been witnessed jumping over them.

What’s more, dams routinely wash-out, particularly over the winter months, turning straight rigid streams into meandering systems bedded with gravels and stones. This happens to be perfect spawning grounds for fish, such as salmonids like the brown trout Salmo trutta or bullhead Cottus gobio.

Even when beavers fail, the ecosystem wins.

Building dams is not an easy task, especially if you don’t have power tools. Beavers, though, have the best tools of all: their own bodies. In his recent book Eager, environmental journalist Ben Goldfarb describes them as “ecological and hydrological Swiss Army knives”.

The original Swiss Army Knife was designed for (you guessed it) the Swiss Army. There was a precise goal for it though: to be able to disassemble, assemble and clean out the rifles the Swiss soldiers used; as well as help with various camp jobs — opening cans and so on.

One can imagine a beaver going through the process of building its home, flipping out different tools as it needs them just like an army officer with a knife.

Like most humans, beavers begin with their eyes: by looking for a suitable location to build their homes. While we may look out for aesthetics and that picturesque view; beavers look out for regions with a steady supply of food, such as the leaves and bark from willow or aspen. They also ensure their homes can hover over an area that is about five feet deep. This allows them to make speedy and invisible entries and exits to their dwellings.

Once the location is set, the beavers deploy the next tool: their long, sharp teeth; which they use to cut trees down. They then scoop mud from river beds, carrying it in their forearms.

Using their strong jaws to carry logs, sticks and shrubs and pile them up near their chosen location, and applying mud to cement the dwelling together (bonus: it also works as an insulator!), they create a strong, stable structure, which can keep out almost every animal except the bear.

Under their house, beavers whip out their forelegs to excavate and create a burrow-like area where they reside. This makes the rest of the dam form a moat of sorts around their dwelling.

If you’re picturing a miniature castle on an island, that’s precisely what the beaver home looks like.

The babbling waters of the River Otter rise high in the Blackdown Hills of idyllic rural Devon. The landscape is quintessentially English, rolling hills patchworked by small farms and bustling hedgerows. Into this quaint sleepy world, our now familiar furry friends have been returned after over four-hundred years of absence.

The beavers that once roamed Europe were driven to extinction by our hunter-gatherer ancestors. Fossil evidence has demonstrated that hundreds of millions of beavers once roamed from Western Europe to the Chinese-Mongolian border, and down into the fertile Tigris-Euphrates basin. By the 20th century, only eight relic populations remained, mostly concentrated in Russia and other Soviet countries. Of late, though, as the health of the environment hangs in balance, there have been attempts to bring them back.

Rewilding is always controversial. Farmers routinely prophesize economic and agricultural doom at the first signs of the wild and woolly. An understandable, albeit tiresome, reaction; after all, their livelihoods are on the line.

In this case, the reintroduction of beavers created some teething issues — literally. The beavers incised a few trees in a local orchard, and a few more tumbled trunks blocked public footpaths. They also flooded small sections of farmland. However, the costs were consistently in the tens of pounds, rarely entering the thousands.

Dams were removed when necessary, and anti-beaver devices such as wire guards around trees or water flow devices will limit the impact as years go by. Such costs are chump change compared to the benefits.

Dozens of dams were constructed by the beavers throughout the tributaries of The Otter, though none on the river itself: dams are used to create safe watery environments, which is unnecessary on deeper rivers. Nature thrives at the interface between two mediums, and the labyrinth of channels and wetlands which formed provided the perfect ecosystem for plants and insects, as well as the creature who fed upon them.

Beaver pools, known as glides, bustled with life, containing thirty-seven per cent more fish than comparable sections of the river. The slender, sinuous brook lamprey (Lampetra planeri), usually a conservation concern, saw numbers boom in the glides, alongside sizable trout and minnow. The study even discovered the fabulously named three-spined stickleback, not found anywhere nearby.

In the nearby ‘Enclosed Beaver Project’ site, common frogs (Rana temporaria) increased from a measly ten pairs in 2011 to nearly seven hundred by 2017, the ponds perfect for their spawn.

Wetlands also aided the recently reintroduced water voles (Arvicola amphibius), who began to thrive despite the presence of their sworn enemy, the invasive American mink (Neovison vison) — primarily attributed for the vole’s decline. Meanwhile, the eponymous otters (Lutra Lutra), normally reliant on holts (natural holes in a riverbank), found the abandoned beaver burrows perfect real estate, as they rarely dig burrows of their own.

As Mark Elliott, who led the River Otter beaver trial said: ‘We’ve all been surprised by these amazing animals’ ability to thrive, once again, in our wetland ecosystems. It also shows their unrivalled capacity to breathe new life into our rivers and wetlands, very few of which are in good health.’

And don’t forget, it’s not just the wetlands: beavers have proven to be good news for humans too.

Following the floods which swept across Britain in winter 2019–20, many are turning to the herbivorous rodents. More specifically, to their dams.

Dams slow the flow of water. During a storm, on average, peak flows are thirty per cent lower leaving a dam system than entering, as millions of litres are stored and gradually released over the following weeks or months, and not hours, as usually happens following a storm. Water leaving the dam is also cleaner and less polluted, containing reduced levels of sediment, as well as nitrogen and phosphorus which seeps from manure, slurries and fertiliser. (Funnily enough, farmers rarely raise this point when complaining).

Unsurprisingly, beavers are becoming a must-have for every landowner across England. Natural England has issued 13 beaver licences since 2017, and large fenced ‘trial’ enclosures now exist in North Yorkshire, Cornwall, Essex, Devon, Somerset and Gloucestershire. Many have escaped such enclosures, their teeth being like bolt-cutters, spreading them further abroad.

Before you know it, a beaver will be coming to a river near you. From near extinction to daring escapes: the beavers are back, and they’re as eager as ever.