Once hunted to near-extinction, the North American beaver is making a comeback /Keystone Features/Getty g e Koni g e Geor

Could nature’s engineers help save California from drought? Macgregor Campbell finds out Beaver fever o m c aturepl. N o/ gg o hel R hel c Mi

OLD wasn’t what drew the first European Known as nature’s engineers, beavers seem and soar while finger-sized blue dragonflies In Sugar Creek, much to Stapleton’s delight, has been to build more channels, reservoirs happily integrated them into their structures. settlers out West. The California gold to magic water out of nowhere. Crucially, their perch on reeds. Translucent baby fish take the faux dams worked. As she wades through and other artificial water infrastructure. Then, in the early 1990s, came an accidental Grush was preceded by the California fur dams also help to store that water. At a time cover under waterlogged sticks. Beavers and soft muck into surprisingly pristine pond Pollock believes beavers are a better solution. experiment. Fish and game officers in Elko, rush: having exhausted what nature could when California faces endless water shortages humans have been busy. “We’re building water, she points out evidence of beavers all Nevada, were working with ranchers to restore supply in Europe and in the eastern American and long-standing drought, could beavers be an ecosystem here,” says Michael Pollock, a around. Sticks with chew marks are strewn two dried-up stream basins that cattle had colonies, trappers set out in search of new part of a more natural solution? researcher with the National Oceanographic across the pond bottom. A scent-mound of Parachuted in obliterated. To recreate a habitat for cutthroat riches. The thick, lush coat of the North Like much of northern California, the area and Atmospheric Administration (NOAA), dried mud stands guard telling interlopers The idea isn’t new. In the 1950s, fish and game trout, they put fences up – fish on one side, American beaver was particularly prized. It around Sugar Creek, just off state route 3, was based in Seattle, Washington state. that the pond is spoken for. Vegetation has officers in Idaho parachuted nuisance beavers cows on the other. Willow, a favourite beaver was traded for every commodity under the once dredged for gold. Streams were forced In 2010, local landowner Betsy Stapleton been stuffed into both dam analogues. “They into new areas, far from humans, where they food and building material, took root. By 2003, sun, shipped around the world and used to into channels and wetlands drained. As a got in touch with Pollock after reading about like to plug every little hole,” says Stapleton. might be able to help with flood control and a colony had moved in and begun damming make clothes and hats. consequence, metres-high mounds of bare some of his research. Pollock was interested For Pollock, Sugar Creek was a test case for habitat restoration. Unfortunately, the impact the streams. Before long, the dry creek beds How fortunes change. The fur rush drove river rock now bake in the sun. But tucked in something called beaver dam analogues. a new way to manage water. When Stapleton of this work was seldom rigorously followed had sprouted into verdant wetlands, which the North American beaver, Castor canadensis, away in the midst of all this rubble, a curious Typically consisting of a line of posts set across first contacted him, the site had just a trickle up. Humans thought of beavers primarily as a attracted other animals too. to near-extinction. Then, after a remarkable scene unfolds. a stream bed and interwoven with willow and of water. It felt symptomatic of the wider problem – out of sight, out of mind. It was never the officers’ intention to lure comeback last century, the once-prized rodent Shrubs swallow the rocks, bulrushes stand cottonwood branches, these faux dams slow issues facing California, namely persistent Later, in the mid-1980s, a wildlife biologist beavers to Elko, but the events proved that became a pest. Now, some say it could be on in a wide expanse of clear, still water, and water down and widen out a stream to form a drought and dwindling groundwater with the US Bureau of Land Management under the right conditions and with very the cusp of a fresh rebranding: not as a prize or cottonwood trees tower over the landscape. pond. The goal? To attract beavers. Putting one resources, neither of which is likely to be eased called Larry Apple attached old truck tyres to little money, beavers could completely a pest, but as a prodigy. In the speckled shadows, yellow butterflies dip up is like prepping beaver real estate for sale. by climate change. Traditionally, the answer small beaver dams and watched as the animals transform an ecosystem. >

36 | NewScientist | 22 October 2016 22 October 2016 | NewScientist | 37 That same process is now at play at Sugar the government could build tens of thousands Where there’s beavers Creek. The adjacent, undammed creeks are dry of smaller dams for far less money and get there’s water: putting in the summer. When they do flow, in autumn beavers to maintain them for free. “They just in the foundations for and winter, the water moves fast, washing all need a little water and a little wood. They can new dams at Sugar the dust and nutrients they pick up out to sea. survive and make a decent living in a huge Creek allowed beavers Come summer, it’s just dry gravel again. variety of situations,” he says. to create a lush It’s not all sweetness and light, however. ecosystem Humans and beavers working in harmony to Water from nowhere restore degraded ecosystems is an alluring At Sugar Creek, on the other hand, the water dream, but the reality is somewhat more gets stuck. Beneath it isn’t just rock but rich complicated. For one, there’s a reason why soil too. NOAA hydrologist Brian Cluer points beavers are considered a nuisance: they don’t out sand and fine dirt that has come from always do what you want them to. Introduce further upstream. In the still waters of the them in the wrong area and they can wreak ponds, it settles. Grasses, reeds and other havoc. Chewed trees, plugged culverts, flooded plants take root in the stuff, locking it and its fields and roads – the same behaviours that moisture in place. With time, a thick base of make beavers excellent engineers are often at rich, moist soil builds up, helping to raise the odds with human infrastructure. Across the water table. US, that means damage costing tens of Cluer says that all this has a huge knock-on millions of dollars each year. il effect. The water seeps down into the ground, Introducing beavers to an area doesn’t c recharging underground aquifers. That always go well for the animals either, says matters because California is depleting its Jimmy Taylor, a wildlife biologist with the US groundwater at an alarming rate. It is now Department of Agriculture, based in Corvallis, tapping into “fossil” water that has been Oregon. Dropping them into a new area can iver Watershed Coun Watershed iver underground for tens of thousands of years. leave them vulnerable to predators and ott R

Farmland is sinking as aquifers collapse. This without enough food while they build Sc is the price you pay for an intensive water their infrastructure. management system predicated on drained Taylor points out that many beaver ranges wetlands and artificial channels, says Cluer. have recovered since the fur trade ended. If a HERE’S LOOKING AT CHEW Slowing water down and storing it in seemingly beaver-friendly area isn’t already natural ecosystems could be much more home to some, there’s probably a reason. How could you not love beavers? They possible. This puts their main predators – effective than creating reservoirs, where half Maybe there are predators, or perhaps the how big an impact beaver restoration might nearly double. It seems that far from being are intensely social and form lifelong wolves, mountain lions and wolverines – the water evaporates, he says. And although food and wood supplies aren’t right. Or make in the western US. harmed by the dams, fish were benefiting pairs. Each family – or colony – splits its at an instant disadvantage. It also beaver dams will never reverse the damage the area could already be claimed: conflict Minimising conflict between beavers and from the wetter, more protected environment. duties: while one animal gathers building encourages aquatic vegetation, which caused by increasing greenhouse gas emissions, between colonies can force one to migrate, humans is a good start, but not the whole What’s more, so far as the team could tell, material, another excavates the pond provides food and building material. Plus, it could help keep at least some of the water possibly into areas where humans live. “It story. Some fish and wildlife managers are there was no change in the number of adult and yet another watches the kits (that’s a dragging a 6-metre log around on the from the rapidly melting California snowpack may be that the area we think is suitable, really concerned that the dams obstruct fish and fish heading upstream to spawn. They seemed baby beaver to me and you), keeping an ground is tough work, but put that same on land – instead of letting it run out to sea isn’t,” he says. In his view, “when humans so will harm stocks. Pollock doesn’t buy the to have no trouble hopping over the dams. eye out for predators or rival colonies. log in a pond and the dog-sized rodent each spring. relocate animals, it’s almost always a failure”. argument. Together with Wheaton and others, “Beavers and salmon have been evolving A single family can create and can push it around with ease. There’s good reason to believe this. Ten Taylor knows this from experience. He and he has recently completed a large-scale study together since at least the Pliocene, 3 million maintain tens of square kilometres of Their tails are incredibly versatile. years ago, Glynnis Hood, a wildlife ecologist his students recently trapped and relocated years ago,” Pollock points out. He says water infrastructure. They thin local Not only do they help with deft at the University of Alberta in Canada, and 38 nuisance beavers near the Oregon coast. “Areas recolonised by preliminary results at Sugar Creek tell forests, both for building material and underwater acrobatics, they are also her colleagues systematically reviewed aerial Sixteen weeks later, more than half had died, a similar story. Before the beaver dam bark – their preferred food – and store it slapped against the water to warn the photos of the province, taken between 1948 many eaten by mountain lions. The dams they beavers had nine times analogues, they counted tens or hundreds in underwater caches of sticks and small colony of imminent threats. Beaver tails and 2002. Beavers returned in 1954, so the built were ephemeral and washed away in the of baby fish in a typical summer. After? logs that also provide homes to baby fish. store fat for the winter, which made team could quantify their impact on the higher winter flows. as much water as before” Thousands. “There’s way more than we can Beavers have webbed feet, them a delicacy during the fur trade landscape. Sites recolonised by beavers had It’s not just resident beavers who dislike count,” says Pollock. transparent eyelids and closable ear days. They also prop their owners up so nine times as much surface water as before interlopers – people living in the area often of the effect beaver dams have on steelhead Life at Sugar Creek is sweet indeed. But will and nose-valves, all perfect for their they can chew on trees, and have an they came back, even in years of drought. The object. Wheaton says one project in Escalante, trout numbers at Bridge Creek in Oregon. In it last? Part of a dam washed out downstream largely aquatic lifestyle. There’s also ingenious circulation that helps regulate beavers proved more influential than climatic Utah, was met with fierce local opposition 2008, the team started building beaver dam during last winter’s high water. Standing in an inner lip behind their impressive body temperature. variations like temperature and precipitation. from ranchers who saw the rodents as pests. analogues along a 32-kilometre stretch of the the middle of the pond with water up to her incisors, allowing them to chew Perhaps the beaver’s most surprising Given the scale of the water problems facing To get around situations like this, his team watershed, eventually completing 121 by 2012. hips, Stapleton points to where the 4-metre- underwater without drowning. They attribute is its anal scent glands. They the western US, beavers seem like a cheap and have been building a software mapping tool to The resident beavers chipped in, building on wide breach was. The beavers have patched tirelessly put together dams, build the produce a substance called castoreum, scalable solution, says Joe Wheaton at Utah help predict where beavers might thrive and top of the artificial dams and creating new it up with sticks, reeds and mud. The water- /Getty S G lodges they live in, excavate ponds and which beavers use as a calling card. State University in Logan, who has worked on stay out of humans’ way. It identifies areas ones too. By 2013, there were 236. storing, soil-building fish factory is fine. She connect them with canals. Humans use it in perfumes and beaver restoration efforts in Utah, Oregon and where water flows are conducive to beavers Before the experiment, the density of smiles. “What’s not to love?” n artore/ N Their aim is to create large ponds so occasionally as a flavouring additive, elsewhere. He says rather than spend billions and cross-checks them against human fish living in Bridge Creek was the same as at

Joel S Joel they can spend as little time on land as typically in substitutes for vanilla. to redirect streams and build a few big dams, infrastructure. They are using the tool to see nearby Murderer’s Creek, but by 2013 it was Macgregor Campbell is a writer based in Oregon

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