These are the golden days of beaver news. Yesterday a glowing report on VPR and today a glowing report on NHPR. But we’ll talk about that later, because this article from New Scientist Magazine has earned top billing.
How beavers could help save the western US from a dry future
By
How fortunes change. The fur rush drove the North American beaver, Castor canadensis, to near-extinction. Then, after a remarkable comeback last century, the once-prized rodent became a pest. Now, some say it could be on the cusp of a fresh rebranding: not as a prize or a pest, but as a prodigy.
Known as nature’s engineers, beavers seem to magic water out of nowhere. Crucially, their dams also help to store that water. At a time when California faces endless water shortages and long-standing drought, could beavers be part of a more natural solution?
Shrubs swallow the rocks, bulrushes stand in a wide expanse of clear, still
water, and cottonwood trees tower over the landscape. In the speckled
shadows, yellow butterflies dip and soar while finger-sized blue dragonflies
perch on reeds. Translucent baby fish take cover under waterlogged sticks.
Beavers and humans have been busy. “We’re building an ecosystem here,”
says Michael Pollock, a researcher with the National Oceanographic and
Atmospheric Administration (NOAA), based in Seattle, Washington state.
Ohlala! Curl up with your saturday morning cuppa and settle in for the best read of the entire week. Any article that starts out with Pollock is going to go places we want to be. We’re all in at this point. Unfortunately that’s all the preview the magazine gives for free but we are old friends right? They didn’t mean to keep us out.
In 2010, local landowner Betsy Stapleton got in touch with Pollock after
reading about some of his research. Pollock was interested in something
called beaver dam analogues. Typically consisting of a line of posts set
across a stream bed and interwoven with willow and cottonwood branches,
these faux dams slow water down and widen out a stream to form a pond.
The goal? To attract beavers. Putting one up is like prepping beaver real
estate for sale.
In Sugar Creek, much to Stapleton’s delight, the faux dams worked. As she wades through soft muck into surprisingly pristine pond water, she points out evidence of beavers all around. Sticks with chew marks are strewn across the pond bottom. A scent-mound of dried mud stands guard telling interlopers that the pond is spoken for. Vegetation has been stuffed into both dam analogues. “They like to plug every little hole,” says Stapleton.
For Pollock, Sugar Creek was a test case for a new way to manage water.
When Stapleton first contacted him, the site had just a trickle of water. It felt
symptomatic of the wider issues facing California, namely persistent
drought and dwindling groundwater resources, neither of which is likely to
be eased by climate change. Traditionally, the answer has been to build
more channels, reservoirs and other artificial water infrastructure. Pollock
believes beavers are a better solution.
At Sugar Creek, on the other hand, the water gets stuck. Beneath it isn’t just
rock but rich soil too. NOAA hydrologist Brian Cluer points out sand and fine
dirt that has come from further upstream. In the still waters of the ponds, it
settles. Grasses, reeds and other plants take root in the stuff, locking it and
its moisture in place. With time, a thick base of rich, moist soil builds up,
helping to raise the water table.
Cluer says that all this has a huge knock-on effect. The water seeps down
into the ground, recharging underground aquifers. That matters because
California is depleting its groundwater at an alarming rate. It is now tapping
into “fossil” water that has been underground for tens of thousands of
years. Farmland is sinking as aquifers collapse. This is the price you pay for
an intensive water management system predicated on drained wetlands
and artificial channels, says Cluer.
Oh my goodness, creating biodiversity AND recharging our bone- dry collapsed aquifers. That’s got to sound pretty good to a lot of bureaucrats out there. Hope the aide to the governor is reading this. We’re at the part of the article where they talk about the ‘buts’ though. But here’s the bad news. I’m braced. Give it your best shot MacGregor.
It’s not all sweetness and light, however. Humans and beavers working in
harmony to restore degraded ecosystems is an alluring dream, but the
reality is somewhat more complicated. For one, there’s a reason why
beavers are considered a nuisance: they don’t always do what you want
them to. Introduce them in the wrong area and they can wreak havoc.
Chewed trees, plugged culverts, flooded fields and roads – the same
behaviours that make beavers excellent engineers are often at odds with
human infrastructure. Across the US, that means damage costing tens of
millions of dollars each year.
Introducing beavers to an area doesn’t always go well for the animals either,
says Jimmy Taylor, a wildlife biologist with the US Department of
Agriculture, based in Corvallis, Oregon. Dropping them into a new area can
leave them vulnerable to predators and without enough food while they
build their infrastructure.
Alright if the most negative voice you got is Jimmy Taylor, I can handle it.It’s funny how this article is turning into a ‘Who’s who’ of beavers and my beaver podcasts isn’t it? You really should go listen to them again just to make sure you know what’s going on. Yes, beavers don’t always survive reintroduction and beavers block culverts. Can we go back to the good news now? No we have to fret about fish first.
Minimising conflict between beavers and humans is a good start, but not
the whole story. Some fish and wildlife managers are concerned that the
dams obstruct fish and so will harm stocks. Pollock doesn’t buy the
argument. Together with Wheaton and others, he has recently completed a
large-scale study of the effect beaver dams have on steelhead trout
numbers at Bridge Creek in Oregon. In 2008, the team started building
beaver dam analogues along a 32-kilometre stretch of the watershed,
eventually completing 121 by 2012. The resident beavers chipped in,
building on top of the artificial dams and creating new ones too. By 2013,
there were 236.
Before the experiment, the density of fish living in Bridge Creek was the
same as at nearby Murderer’s Creek, but by 2013 it was nearly double. It
seems that far from being harmed by the dams, fish were benefiting from
the wetter, more protected environment. What’s more, so far as the team
could tell, there was no change in the number of adult fish heading
upstream to spawn. They seemed to have no trouble hopping over the
dams.
“Beavers and salmon have been evolving together since at least the
Pliocene, 3 million years ago,” Pollock points out. He says preliminary
results at Sugar Creek tell a similar story. Before the beaver dam analogues,
they counted tens or hundreds of baby fish in a typical summer. After?
Thousands. “There’s way more than we can count,” says Pollock.
Ohhh yes, that’s the kind of research I like best! The snappy ‘take that’ kind of research! If I didn’t know better I’d think that maybe this would change the way people looked at beavers. I’d think that this article would open eyes, and minds. But I’ve been in the beaver biz a long time. People are very, very stubborn. I guess I should be happy if it changes a few minds and gives some others pause.
Oddly enough, this article does a lot of heavy lifting for the rodents but makes the decision to end on an appreciation of their anal scent glands. Hmm? Not the note I would have ended on, but the rest is wonderful so we’ll let this slide.
How could you not love beavers? They are intensely social and form lifelong pairs. Each family – or colony – splits its duties: while one animal gathers
building material, another excavates the pond and yet another watches the kits (that’s a baby beaver to me and you), keeping an eye out for predators
or rival colonies.
A single family can create and maintain tens of square kilometres of water infrastructure. They thin local forests, both for building material and bark – their preferred food – and store it in underwater caches of sticks and small logs that also provide homes to baby fish.
Perhaps the beaver’s most surprising attribute is its anal scent glands. They
produce a substance called castoreum, which beavers use as a calling card.
Humans use it in perfumes and occasionally as a flavouring additive,
typically in substitutes for vanilla.
Lets give MacGregor the benefit of the doubt and lets assume that he wanted to finish the article on some grand sweeping note about beaver benefits or how society misunderstands the gift it was given, and his small minded editor in gaberdine made the article end on anal scent glands, because ew! People will tell their friends!
Overall this is a fantastic read and just in case you want to pass it along to your friends or senators I will risk the long arm of the law and link to it here. Shhh,
On a local note, I heard from Leslie this morning that our wayward beavers have nearly finished the tree they took down and she had fun watching them all evening. I also heard back from the grounds keeper at the junior high that he is grateful for the information and loves nature and will keep my number handy. So that’s about the best we could hope for.
You do everything you can to raise your children right, and get the right information out there, but at some point they go out in the world and you just have to trust things will work out.
