Beavers Take Free Reign of Canyon
While Reedies were busily studying for midterms, the beaver families living in Reed’s canyon have been quietly transforming the canyon’s east end back into the marsh that Reed Lake once was. Each night at dusk, around three beaver families migrate from their dens near the Amphitheatre to the east end of the Canyon to feed and build their dams. Over the past two years, they have lent a helping tooth to Reed’s Canyon Restoration Project, according to Zac Perry, who has managed the project since its inception in 1999. The beavers have built four large dams, as well as blocked numerous other side-channels.
Perry doesn’t have any plans to interfere with the beaver’s activity. He says, “We’re not going to intervene with the homes and functions of the beavers.” The rising water levels pose no threat to nearby buildings. Because of this, the restoration project has the freedom to adapt their procedures to specific canyon situations as they arise. Perry calls the liberty “just another wrinkle in Reed Canyon that makes it better than most.” Aside from humans, the beavers are the main influence on hydrological changes in the Northwest watersheds. As Perry says, “They’ve been here before the restoration, they’ll be here after.”
The dams help protect the canyon in numerous ways both directly and indirectly. The aptly named reed canary grass grows in much of Europe, Asia, and North America, but is an invasive non-native species in Oregon. Since the beavers have raised the water table by around three feet at the end of the canyon, the marshes that would normally be prime habitat for canary grass are now completely submerged. This rots the grass’s thick root system and allows geese to feed on the grass more easily.
The dams also facilitate the salmon runs that the Canyon Restoration Project has been working so hard to restore. Where the land bridge now stands there was once an extensive beaver dam, which then became a swimming pool, then a fish ladder in 2001. Where the beavers have built their dams, fish traveling upstream are able to jump from one beaver pool to the next, essentially using a beaver-created fish ladder. The deep water also helps the fish travel more easily and safely through the channels.
Beavers gnaw on trees for a number of reasons, but according to Perry, “the beavers will only chew 10% of the tree.” They feed on the xylem in the bark of the trees, metabolizing the sugar-water they lick off the bark shreds. Beavers, like nutria, have teeth that grow continually throughout life, so they chew to keep them short. Most importantly for the canyon, the beavers use branches to construct their lodges and dams. Fortunately, the beavers use mostly non-native trees for their dams as native and “sacred” trees have wire cages round their bases.
Because Reed Lake is fed by 54-degree spring water, the lake is never at risk of freezing over, so there’s no actual need for beavers to build lodges. In lieu of lodges, the beavers burrow underneath trees near the water’s edge and use the logs as the roves of their dens. Some of the beaver dens are so large that “two people could lay down inside,” says Perry. The beavers build dams to create more livable habitats and to protect themselves from coyotes.
Perry calls the Canyon the “flagship restoration project for the city of Portland.” Since the restoration project began in 1999, there have been 67 senior theses on the canyon, more than in the 50 preceding years. Perry was quick to note that the Reedies who help during Canyon Day and other events are the real heroes. Students and volunteers built all the bridges, pathways, and benches in the Canyon. He says, “The Canyon that you enjoy today is a reflection of what students have done in years past.” Perry encourages students interested in helping the beavers restore the Canyon to its natural beauty to apply for Canyon Crew or volunteer on Canyon Day, April 6.