GIWS researcher mentioned in Canadian Geographic
By Frances Backhouse, Canadian Geographic
December 3, 2012
At the turn of the 19th century, many people thought Canada’s national animal was a goner — a doomed species that had passed the point of no return. One notable pessimist was Horace T. Martin, a Canadian Fellow of the Zoological Society of London and author of Castorologia or the History and Traditions of the Canadian Beaver. “As to the ultimate destruction of the beaver, no possible question can exist,” declared Martin in 1892, noting that “the evidences of approaching extermination can be seen only too plainly in the miles of territory exhibiting the decayed stump, the broken dam and deserted lodge.”
One hundred and twenty years later, on a warm June evening, I sit on the shore of a massive beaver pond in Ontario’s Algonquin Provincial Park, watching water bugs etch ephemeral lines on the glassy surface. I chose a spot near the long, curved dike that contains the pond at this end. From this vantage, the structure is unremarkable. Viewed from downstream, as I would do later, it stands an impressive two metres high, a thick, angled rampart of sticks, mud and sprouting greenery.
Within 10 minutes of my arrival, one of the dam builders appears. At first, it looks like a plank of waterlogged wood, but as it nears, I start to make out details: knobby ears, black-bead eyes, water-slicked mahogany fur. When it gets close enough that I can see its nostrils flaring, I expect a startled dive. Instead, it approaches to within a metre of the shore and cruises back and forth in front of me for several minutes.
Peering down into the tea-coloured water, I observe the ruddering action of its tail and the slow, alternating kicks of its webbed hind feet. Its small front paws remain tucked close against its chest. The beaver watches me intently and intermittently emits a low rumble that sounds like a cross between a growl and a purr. Finally, it swims over to the dam, clambers out of the water and stands as if posing for the Canadian nickel, then belly-flops back into the pond and paddles away. How pleased Horace T. Martin would have been to know his prognosis was wrong.
The beaver revival is, indeed, one of the continent’s great conservation success stories; beavers are thriving throughout their traditional territory in North America. But as beavers continue to multiply, not everyone is cheering them on. Each year, the average adult beaver cuts approximately one metric tonne of wood — about 215 trees — for food and building materials. Not only do we complain when they compete with us for timber or meddle with the scenery, we also object when their dams flood highways, farm fields and waterfront real estate. In 2010, one even killed a husky in a suburban park in Red Deer, Alta.
Yet a growing body of research suggests that we need more beavers not fewer, that beavers perform a vital service to the riparian world that will be particularly needed in the drought years ahead. It may be an argument Canadians don’t want to hear.
Before the European invasion of North America began in the late 1400s, beavers inhabited almost all of what we now call Canada and the United States, plus a sliver of northern Mexico. Except for the driest western deserts and the alligator-patrolled swamps of the Florida peninsula, they ranged from coast to coast and from just south of the Rio Grande to the Arctic treeline, as well as north along the Mackenzie and Coppermine rivers to the Arctic Ocean.
Pre-contact beaver-population estimates vary widely, from a conservative 60 million to an extravagant 400 million. In the words of explorer and cartographer David Thompson, the entire northern half of the continent was originally “in the possession of two distinct races of Beings, Man and the Beaver.” Thompson’s authority to make such statements came from surveying and mapping one-sixth of North America and talking with countless aboriginal elders who had known of the beaver’s glory days.
Cherie Westbrook, an associate professor in the University of Saskatchewan’s department of geography and planning, corroborates Thompson’s anecdotal evidence and brings an ecohydrologist’s perspective to the discussion. According to Westbrook, 85 percent of all watercourses in the United States — and a comparable, though unquantified, percentage in Canada — are headwater streams and, therefore, small enough to be dammed by beavers. This continent-wide network of fine blue lines represents a wealth of potential beaver habitat. “We’re talking about beaver in nearly every headwater stream across North America prior to European colonization,” says Westbrook. It was a bonanza that would set off North America’s first natural resource stampede.
At first, the fur trade was merely a sideline for the cod fishermen who sailed back and forth across the Atlantic in the late 1400s and early 1500s. But their discovery of Castor canadensis could not have come at a better time for the Old World, where an insatiable demand for hats made from the beaver’s dense under-fur was fast depleting the supply of materials. By the mid-1500s, the once common Eurasian beaver, C. fiber, existed only in a few isolated corners of Scandinavia, Siberia and the Far East, and the rush for North America’s “brown gold” was on.
French, English and Dutch traders shipped tens of thousands of beaver pelts annually in the early decades of the fur trade. Then they pushed inland and intensified their efforts. Throughout the 1700s, annual exports of beaver pelts rarely dipped below 100,000. Some years, they may have topped 300,000. But the real problem wasn’t the body count. It was the fur trade’s relentless, colony-obliterating progress across the continent, which wiped the species right off the map even as the cartographers were drawing it. Sheer numbers were no match for the traders’ technology and greed.
The first concerted attempt to arrest the beaver’s precipitous decline was led by George Simpson, governor of the Hudson’s Bay Company. Between 1821 and 1850, he imposed a series of trapping moratoriums and quotas on the company’s western interior districts and prohibited agents at those posts from buying the skins of beaver cubs and summer-killed adults, whose fur was of little commercial value. These conservation measures were moderately successful but too geographically limited to make a difference. South of the border, independent American trappers were scooping up beaver pelts — “hairy banknotes” in the lingo of the mountain men — as fast as they could find them. Counter to his own conservation efforts, Simpson responded by aggressively expanding his operations west of the Rockies, deliberately eliminating beavers from parts of Oregon and Washington before rivals could get there.
By the early 1900s, there was scarcely a beaver to be found south of the forty-ninth parallel and throughout much of Canada. Records for Rupert House, the Hudson’s Bay Company’s oldest trading post, reveal just how dire the situation was, even in a remote area like James Bay. In the winter of 1928-29, after months of scouring the 25,000 square kilometres around Rupert House, the community’s desperate trappers had only four beaver pelts to show for their efforts.
Meanwhile, hundreds of kilometres to the south, Archibald Belaney, an English immigrant who had adopted a First Nations persona and the alias Grey Owl, had taken up the beaver’s cause. In 1928, after years of making his living as a trapper in northern Ontario and Quebec, Belaney swore off trapping and set out to save the species he had come to see as a symbol of Canada’s vanishing wilderness. His passionate and eloquent writings, published under his pseudonym, soon drew international attention to the beaver’s plight.
In 1928, the Dominion Parks Branch made a 13-minute, black and white silent motion picture featuring Grey Owl — wearing his customary buckskin jacket and moccasins — and his two pet beavers, Rawhide and Jelly Roll. No professional filmmaker had ever filmed beavers in a natural setting, and Beaver People (which can be viewed on the National Film Board website) was a hit.
The following year, the parks commissioner offered Grey Owl a job and a new home by a secluded lake in Saskatchewan’s Prince Albert National Park. In his role as a live tourist attraction, the lanky, blue-eyed “Indian” solemnly greeted the hundreds of visitors who canoed and hiked to his cabin each summer and introduced them to Rawhide and Jelly Roll. The celebrity pair always came when he called, assured of receiving apples, peanuts and other treats. They also fulfilled their other obligation, producing annual litters to help rebuild the park’s decimated beaver population.
Grey Owl’s death in 1938 spared him from seeing how quickly his beloved beavers fell into disfavour once they became plentiful. The first systematic survey of Prince Albert National Park, conducted in 1935, pegged the resident beaver population at approximately 500. By the 1940s, park officials were live trapping “surplus” beavers and relocating them to other public lands in a futile attempt to curb their numbers. In 1952, with the population nearing 15,000, they switched to lethal traps and killed thousands of beavers before moving to a more benevolent management approach a few years later.
Prince Albert National Park’s beaver boom was part of a continent-wide resurgence that is still under way. At the start of the 20th century, the number of survivors may have been as low as 100,000. Since then, the population has climbed to an estimated 20 million and the species is again generally thriving in every American state, as well as throughout its historic Canadian range. Beavers are not exceptionally prolific — most don’t begin breeding until the age of two or three, and the monogamous pairs typically raise only two to four kits a year — but their numbers increased steadily once they were freed from the tyranny of unregulated trapping. Young adults, following their natural instinct to disperse, rediscovered habitat that had been vacant for generations, and wildlife managers started restocking places the beavers could not easily reach.
The beaver revival is something worth celebrating, but if beavers are in the news, it is usually for all the wrong reasons. In 2011, for example, Canadian Senator Nicole Eaton denounced Castor canadensis in a Senate speech as a “toothy tyrant” and a “dentally defective rat” that wreaks widespread havoc. Her personal grudge was against the beavers that move in under the main dock of her Georgian Bay, Ont., cottage every summer, undeterred by repeated evictions and lodge demolition. While the Canadian public overwhelmingly rejected Eaton’s proposal to dethrone our bucktoothed national symbol, one group of Ottawa Valley farmers applauded her statement and spoke out about their own frustrations with the species. Supported by the local conservation authority and nearby municipalities, they had hired a contractor to trap beavers and destroy dams. “It’s a war,” one of the farmers told a National Post reporter. “It’s really a war.”
The governments of Saskatchewan and Manitoba don’t use such provocative language, but they do pay incentives for dispatching “nuisance” beavers. On Prince Edward Island, where beavers have been eradicated and reintroduced twice, most recently in the 1940s, the province is now culling the population. One way or another, beaver numbers are controlled almost everywhere the species has re-established itself.
Cherie Westbrook of the University of Saskatchewan is an outdoorsy-looking woman with sun-bleached, shoulder- length hair and a wide smile. She was born in 1974, the year before Canada’s Parliament granted the beaver official status as a national symbol. Growing up in southern Ontario in the presence of a rapidly rebounding beaver population, she developed an interest in the species. Later, as an undergraduate student and a budding hydrologist, she discovered that beavers were not particularly popular with her fellow scientists. “We had beaver everywhere,” she recalls, laughing, “and they were always screwing up your hydrology studies.” Rather than being put off, however, she wanted to learn more about how these four-legged engineers shape landscapes and influence water dynamics.
After completing a Ph.D on beaver-assisted river valley formation in the Rocky Mountains at Colorado State University, Westbrook returned to Canada to launch the University of Saskatchewan’s wetland ecohydrology research program. She and her graduate students are now investigating the hydrological impacts of beavers in various prairie, boreal forest and mountain ecosystems.
Beavers build dams to create deep-water reservoirs that won’t freeze solid in winter and trap them in their homes or dry up in summer and expose lodge entrances. Dams also increase the amount of swimmable water and reduce the need for risky overland excursions to reach target trees. The above-ground effects of these works are conspicuous: ponds strung like pearls along narrow creeks; small lakes that balloon out into sprawling reservoirs. Less obviously, dams also elevate and stabilize the water table by storing and gradually releasing precipitation and runoff. The lush vegetation that thrives around beaver ponds hints at this influence, but until recently, it was underrated.
“We hadn’t understood how large an area a dam could affect in terms of hydrology,” says Westbrook. “It’s considerably larger than we thought back in the 1980s.” In unconfined terrain, such as a wide valley bottom, water that seeps into the soil around a beaver pond can travel up to two kilometres underground, raising the water table throughout the zone. The stabilizing effect on groundwater supplies can be equally dramatic. At one of Westbrook’s study sites, in the front ranges of the Rocky Mountains west of Calgary, the water table typically drops between 1 and 1.5 metres each summer — except where beavers are active. There, the annual decrease is a mere five centimetres.
Beaver dams also alter downstream hydrology as impounded water enters underground flow paths and rejoins the surface flow below the dam long after the rain clouds have cleared or the spring melt has ended. “It might be a kilometre downstream, it might be two, it might be 200 metres,” says Westbrook, “but if the water gets into the groundwater system, it moves a lot slower. What you’re doing is increasing the amount of low flows, and that’s what’s going to drought-proof the system.”
Since most hydrologists prefer to conduct their research without beavers around to complicate things, studies like Westbrook’s are relatively rare. She says the wide-scale effects of beavers are little understood, but she has no doubt that the species’ near-annihilation had major hydrological, geomorphological and ecological consequences. “I think it fundamentally changed the way watersheds operate.”
Like Westbrook, Glynnis Hood, an associate professor of environmental studies at the University of Alberta, is working on addressing our ecological amnesia and determining what beavers mean to North America. Fittingly, Hood works in the Beaver Hills, just east of Edmonton.
Pocked with shallow sloughs and pothole lakes, this rolling, hillocky landscape lost its namesake in the mid-1800s and remained without beavers until 1941, when a few individuals were reintroduced to Elk Island National Park. When Hood and her co-investigator Suzanne Bayley analyzed park beaver census figures, climate data and aerial photographs for the period between 1948 and 2002, they discovered that wetlands with active beaver colonies had nine times more open water than those without, regardless of the amount of precipitation. In 2002, which was drier than the notorious Dust Bowl era of the 1930s, the beaverless wetlands were visibly more parched than the occupied sites; some were even reduced to mud flats.
“Our results,” wrote Hood and Bayley in a journal article published in 2008, “confirmed that beaver have an overwhelming influence on wetland creation and maintenance and can mitigate the effects of drought.” Citing climatechange models that predict increasingly frequent and persistent droughts, they recommended that we make more of an effort to coexist with beavers — by installing perforated pipes to regulate flow, for example, instead of removing problem dams — and even recruit them to help with wetland rehabilitation projects. While the language may be academic, the message is clear: we need to rethink our relationship with beavers and learn to appreciate them as stewards of our most precious resource.
Another day, another beaver pond, this one in the high, dry Chilcotin Plateau country of the Central Interior of British Columbia. The fur trade came late to this part of the continent, but was just as devastating here as elsewhere. During the first half of the 19th century when beavers were absent from the Chilcotin, creeks and wetlands stagnated and the ecosystems they supported collapsed. It took the beavers’ return to heal the landscape and refill ponds like this one.
I see the wake first, then the wedge-shaped head and a sliver of back. The beaver’s blunt nose creases the water, but not even a ripple betrays the hidden kicks that power its smooth, forward momentum. Suddenly, the tail flicks up and smacks the surface with a gunshot crack. As the beaver corkscrews out of sight in a blur of brown, sunlit droplets explode like fireworks. Gone, but not gone for good. Smiling, I watch the expanding circle of wavelets vanish into the cattails.
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