Well, I’ll be dammed . . .
Castor canadensis may offer us an environmental second chance, it seems
There’s a scene in the movie The Longest Day where a German general slaps his forehead and says: “Normandy, how stupid of me.”
Glynnis Hood had the science version of that in 2002 — a moment when casual assumptions are suddenly replaced by something that, while unexpected, starts to look blindingly obvious in the reflective light of hindsight.
Now a professor of environmental science at the University of Alberta, Hood was then doing research for her PhD on beaver ecology in Elk Island National Park, just east of Edmonton.
She was armed with a unique trove of material, including census data on beavers since they were reintroduced to the park, starting in the 1940s, as well as aerial photographs from 1948 onward.
Combine that with weather statistics and you have a lovely set of data points, not least because 2002 just happened to feature the worst drought on record.
Better yet, there’d been an earlier though less severe drought in 1950, a year that saw 47 per cent more precipitation than in 2002. So you’d be forgiven for thinking the amount of open water still on the land would have been much greater in 1950.
You’d also be wrong. It turns out that, in locations where the beaver had yet to be reintroduced by1950, there had actually been 61 per cent less open water than there was in 2002.
The key variable wasn’t precipitation. It was the presence of beavers, whose deep-water ponds and connecting channels were actually mitigating the effects of severe drought.
“They’re really hydrological engineers,” says Hood. “Everything they do is about maximizing water.” HOOD’S WORK figures prominently in The Beaver Whisperers, a documentary by Jari Osborne that airs March 28 on CBC’s The Nature of Things.
It also reflects how scientists and environmentalists are starting to amend some long-held views of Castor canadensis. The beaver may be Canada’s national symbol, adorning everything from the nickel coin to the Roots logo, but our relationship with the world’s second-largest rodent has long been oddly conflicted at best.
However much this country might owe its existence and geography to the beaver, this is merely because, in our pursuit of wealth, we were so busy trying to kill the furry beasts.
At this, we proved to be enormously successful: in London alone, roughly 4.7 million beaver pelts were sold at auction between 1769 and 1868.
By 1900, we’d taken an animal that once ranged from coast to coast, from the Gulf of Mexico to the Arctic, and reduced it to an endangered rump.
Over the course of centuries, we had simply given beavers the same treatment we gave the passenger pigeon (now extinct) and bison (nearly so at one point).
But here’s the thing about beavers: they are astonishingly resilient, having been on the planet for roughly 30 million years, through all manner of predation and climate change.
Today’s beaver somehow managed to survive the great Ice Age while its larger cousin, Castoroides ohioensis, did not. The latter, about the size of a black bear, went the way of the woolly mammoth and sabre-toothed cat.
So there’s that to admire. But can we now learn to love something we, rather than glaciers, once nearly exterminated, and which many people still regard as a pest whose damming of culverts can flood rural roads?
Scientists like Hood believe we should, and it’s not just because beavers have survived climate change in the past.
In our own age of global warming, beavers may offer us a kind of environmental second chance, courtesy of their ability to preserve water resources, mitigate drought and boost biodiversity. By helping them, we help ourselves.
Just how many beavers now populate North America — and hence the extent of their recovery — remains an open question. Hood, for one, is cautious about offering an estimate, save that any habitat capable of supporting beaver probably has them today.
“They’ve come back as much as they can,” she says. “They have done a remarkable job.”