Return of the ecosystem engineers
Return of the ecosystem engineers
After being trapped out, scientist working to restore healthy beaver population to Wyoming landscape
By Mark Davis
A giant rodent, identified in those words, won’t find a lot of love in many social stratospheres. Yet a Wyoming terrestrial habitat biologist has dedicated the past five years of his life to repopulating beavers — our largest rodent. Without them, the Big Horn Basin’s habitat will continue to suffer.
Targeted for their fine fur, beavers were trapped nearly into extinction during the early stages of America’s colonization. They were considered nothing more than an exploitable resource. Great frontiers were opened by explorers seeking the pelts. They were so valuable, most pioneer families had members of the extended family that would chase the beavers down every river, creek and stream.
The fur trade was based on pelts destined either for the luxury clothing market or for the felting industries, of which hatting was the most important.
Hats were considered more than just an accessory for many hundreds of years and beaver fur made the best hats. Millions of hats were being made each year for centuries and demand for beaver pelts drove the price to more than $2 in the early 1800s — a time when very few made as much for a full day of labor.
By the latter part of the 19th century, beavers were all but extirpated in most riverine habitats in America. Silk soon replaced beaver felt in hats and the boom times were over.
Left in the wake of unregulated beaver trapping were wounded habitats.
“One of the most fascinating eras of the history of this continent, the mountain-man era, also has a darker side to it; a more tragic side,” said Jerry Altermatt, the Wyoming Game and Fish Department’s Cody region terrestrial habitat biologist, during a presentation for a standing-room only crowd at the Buffalo Bill Center of the West’s Coe Auditorium.
“That was how basically a European fashion for apparel spawned an ecological catastrophe,” he said.
In Wyoming, the lack of beavers and their life-supporting dams caused channel incision. The vertical erosion disconnects the channel from the flood plain during high water periods.
“You want the water to come out of the banks, because that’s one of the ways that … floodplain gets water,” he explained.
It also lowers the water table. The combination of the two geomorphic conditions removes floodplain vegetation with upland vegetation. Instead of having willows and sedges, you get sagebrush, dry-land upland species of grasses and possibly juniper, he said.
When you translocate beavers to incised riverine habitats, they build dams and, over time, wetlands can be restored, improving the habitat for many species.
Beaver dams not only created deep pools that supported large amounts of wildlife and plant-life, they trapped sediment. One study done on Currant Creek, in southwest Wyoming, showed suspended sediment loads dropped by 90% after the reintroduction of beavers. Another study in Washington showed that one dam can hold an average of 266 cubic-yards of sediment.
“Just to be able to visualize, 266 cubic-yards is 20 dump truck loads,” he said.
Altermatt starts each translocation of beaver families by identifying habitat capable of providing shelter and food for the species. The crew prepares the sites by building temporary shelter for the beavers, man-made dams to create a pool that can hold the species and supplying the feisty critters with an established food source.
He uses willow and aspen branches to entice them to stay. The branches are the beavers’ favorites, like pigs-in-a-blanket at a Super Bowl party for us.
Only then does he start looking for problem beavers. He can only live trap them in April or late fall, due to their tendency to overheat and not wanting to disturb the raising of kits, or baby beavers.
He also has to trap the entire family, waiting until they’re gathered before releasing them. This was problematic. He designed and built the department’s beaver trailer with donated materials provided by the Wyoming Outdoorsmen and other “generous donors” to give them a good place to hang out until the entire family is together. If he releases them one at a time, they will leave the scene to search for their colony. The species are monogamous, mating for life for the most part.
“The first beaver is always the easiest to catch,” he said. “Almost every time I trap, I get one the first night. I call it the dumb one. The smart one might take a week or two to get.”
As he catches them, he checks each beaver for health and age before transport to what he hopes will be their new home. If they don’t like what they see, they’ll likely move downstream and he has to start again.
The beavers are fitted for GPS transmitters, to track the individuals, and then they survey the areas as the beavers do what they do, often using drones to get a good look at the transformation of the habitat.
Altermatt works under the radar, hoping his work goes unnoticed by area trappers. The laborious work is worth it, he said. Expanding the wetland area around the creek “is the biggest benefit for terrestrial wildlife,” he told the Tribune on a recent translocation project in Park County. The location was kept secret to give the family of rodents a chance to get established.
One might ask, why not simply install man-made analog dams instead of doing all the work it takes to reestablish beaver populations? It remains less effective to build a man-made dam than it is to let the pros do the work, he said.
“They’re much smarter than we are,” he said of beavers. “They know where to build the dams where they’ll last and they do it better than we can.”
On one recent project in the Absaroka range the department released 15 beavers — eight as a family unit and seven individuals. There’s now four or five successful colonies with 54 dams and approximately 25 acres of reclaimed wetland habitat.
“Beavers are a very economical way to build dams compared to if we had to build them ourselves,” he said.
The large crowd in attendance may have surprised some folks. Lunchtime Expedition attendees have a reputation for being intellectually curious and this was a topic that several people in the audience have asked for on more than one occasion, said Corey Anco, curator of the Draper Natural History Museum.
“Beavers are fascinating animals. Maybe not everyone has seen one in the wild but if you were to ask what beavers build, they’d likely all say dams! Their impact to the environment is enormous proportionate to their size,” he said. “How many animals can you think of as large or small as beaver that change their environment in as drastic of a way?”
There is also the allure of the ‘Mountain Man’ era, Anco theorized.
“Beaver trapping and the fur trade were big parts of Wyoming’s history. People often romanticize history and love to hear about the history,” he said.
Anco said the department’s efforts to help restore beavers to northwestern Wyoming is an effort to restore lost ecosystem services and increase the quality of habitat for other species.
“Flood control, water filtration, aquifer regeneration, fire breaks and refugia; these are all ‘services’ beavers provide free-of-charge if we tolerate and promote their existence on the landscape,” he said. “Wetlands created by beavers create prime habitat for wildlife that also carry economic importance such as fish and game birds.”
Altermatt has been with Game and Fish for 30 years and lives in the Powell area. While usually fairly docile creatures, Altermatt has experienced being charged by an angry beaver. They’re not quite as ferocious as a charging grizzly bear — which Altermatt has also experienced — but encounters with any wild animal can be dangerous.
If they only knew how lucky they are to have Altermatt, and science, now on their side.