“Lefty”, the Pokesberry creek beaver, had cautious observers last night. They noticed that he appears to use his hand – just not his arm. They are concerned about grooming – that makes sense – but hopefully he can persuade a family member to do that side – and the temperature stays mild – for the time being things seem stable, Stay tuned.
Meantime there’s a nice beaver article about restoring beavers for fish that deserves our attention. In Washington of course. It looks to be a re-work of the academy of sciences article but that’s just fine. Of course you already know who its by, right?
They Will Build it
The sentiment that Castor canadensis is little more than a tree-felling, water-stealing, property-flooding pest is a common one. In 2017, trappers in Washington State killed 1,700 “nuisance” beavers, nearly 20 times more than were relocated alive. In neighboring Oregon, the herbivorous rodents are classified as predators, logic and biology notwithstanding. California considers them a “detrimental species.” Last year alone, the U.S. Department of Agriculture eliminated more than 23,000 conflict-causing beavers nationwide.
Running countercurrent to this carnage is another trend: the rise of the Beaver Believer. Across North America, many scientists and land managers are discovering that, far from being forces of destruction, beavers can serve as agents of water conservation, habitat creation, and stream restoration. In Maryland, ecologists are promoting beaver-built wetlands to filter out agricultural pollutants and improve water quality in Chesapeake Bay. In North Carolina, biologists are building beaver-like dams to enhance wet meadows for endangered butterflies. In England, conservationists have reintroduced the Eurasian beaver (Castor fiber) in hopes that their pond complexes will attenuate destructive floods. And in Washington, where a century of habitat loss has devastated salmon, the Tulalip Tribes are strategically dispatching beavers to support the fish so integral to their history and culture.
Where there’s a beaver there’s a believer, I always say! Our favorite thing EVER is for beavers to go where they choose and people adapt, but this ain’t bad either.
That beavers benefit salmon is, in some quarters, a provocative claim. Many biologists historically regarded beaver dams as stream-choking barriers to fish passage. In the 1970s, Washington, Oregon, and California even passed laws mandating the removal of in-stream wood, beaver dams included. More recently, a 2009 proposal funded by the Atlantic Salmon Conservation Foundation suggested eradicating beavers from 10 river systems on Prince Edward Island and employing trappers to enforce “beaver free zones” in others.
The notion of purging beaver dams to allow salmon to pass, however, doesn’t stand up to scientific scrutiny. One 2016 study documented individual salmonids traversing more than 200 beaver dams on their way to spawn in Oregon streams, suggesting that fish have little trouble negotiating the obstacles. Far from harming salmon, in fact, beavers create indispensable fish nurseries. By filling up ponds and digging canals, beavers engineer the deep pools, lazy side channels, and sluggish backwaters that baby salmon need to conserve energy and evade predators like great blue herons. Today, the National Marine Fisheries Service considers “encouraging formation of beaver dams” vital for recovering Oregon’s endangered coho populations.
Of course beavers are good for salmon. Remember that there used to be millions more of both species, and no one to rip out the dams. How do you think that ever happened?
“Beavers create complex habitat and enhance local biological diversity in a way that’s really unique,” says Michael Pollock, an ecosystems analyst at the National Oceanic and Atmospheric Administration who’s among the beaver movement’s grandfathers. “They do a much better job of managing these systems than we do.”
Well of course they do. It’s a long article with all kinds of awesome running through it. You might want to go see for yourself. I will just leave you with some pithy closing arguments.
While expanded ponds are beavers’ most visible hydrologic impact, their ability to recharge groundwater might be an even greater contribution. At the Tulalip’s relocation sites, Ben Dittbrenner has found that for every cubic meter (264 gallons) of surface water beavers impound, another 2.5 cubic meters (660 gallons) sinks into the earth. As that water trickles through the soil, it cools off, eventually reemerging to mingle with streamflows downriver. Elsewhere, such hyporheic exchange between surface- and groundwater keeps streams hydrated later into the dry season, turning seasonal creeks perennial. Dittbrenner’s research suggests that beaver-facilitated cooling and mixing also reduces water temperatures by more than 2 degrees Celsius (about 3.5 degrees Fahrenheit), a huge boon for heat-sensitive salmon and trout.
Although beavers won’t singlehandedly save us from climate change, such findings suggest they might be able to help our stressed water supplies adapt to a warmer future. “By 2100, we’re expecting to see snowpack, which is basically our water storage reservoir, disappear throughout a lot of the Cascades,” Dittbrenner says. “I’m curious whether beavers could make up an appreciable storage component of that lost snowpack.”
Ahh Ben! Whatever are we ever going to do without you? Be very, very sorry, that’s for sure. I found out recently that he won’t be able to make it to the festival this year because he’s going to be sent to South America to write about CAPYBARA fer crying out loud.
Talk about your rodenta non grata!
