Beavers Support Salmon Habitat in Elwha River

Looking for beaver activity in the expansive Elwha River valley is daunting. But the key is to keep eyes on the ground, looking for any signs – foot tracks, scat, tail drag, beaver dams, pencil-sharp tree stumps and wood shavings.

The Lower Elwha Klallam Tribe wildlife staff heads out daily for a week or two in the winter to bushwhack through thick cottonwood and willow trees to find any of these signs in the former lakebeds of Aldwell and Mills, where the Elwha River now runs.

The work is part of the tribe’s bigger study on how wildlife is using the lakebeds since the river’s two fish-blocking dams were removed between 2011 and 2014. The idea is that the beavers’ tree-cutting and dam-building activities will potentially alter the river’s flow and create pools important for coho salmon fry habitat.

“Our big interest is documenting if and how beaver are recolonizing these habitats that were formally inundated with water,” said Kim Sager-Fradkin, the tribe’s wildlife program manager.

“We know from previous studies that beavers are most commonly found at the mouth of the river, where they are able to build dams in the estuary,” she said. “In the mainstem of the Elwha, because the river is so big, they are generally bank dwellers. But we feel like there is a possibility that in these new floodplain habitats created by dam removal and the emptying of the reservoirs, they may end up building dams to block side-channel habitat.”

A consistent sign of beaver activity this winter has been willow and cottonwood tree stumps, cut either into the shape of a sharpened pencil or at a sharp angle, with small teeth marks.

A beaver-cut tree stump.

Staff take note of each stump, including where it is located, what kind of tree cover and sediment surrounds it, how close it is to the river, and how many other cut stumps are within a few meters of it, indicating the types of habitat used by beavers and the intensity of that use.

“Beavers are frequently considered ecosystem engineers,” Sager-Fradkin said. “Their habit of cutting down trees to build dams helps with restoring areas in need of better salmon habitat.”