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About Vernonia's voice. (Vernonia, OR) 2007-current | View Entire Issue (June 6, 2019)
community june6 2019 Beavers are Eager to Help Restore Watersheds continued from front page Beavers are considered a key- ence coho salmon recovery in Oregon’s confining hillslopes that will easily cre- stone species – a plant or animal that Coast Range. ate a floodplain and develop into a pond plays a critical role in how an ecosystem The BDAs Trask and his crew behind the dam. functions – a species which would dras- constructed in the Tillamook Forest in- Because this is a pilot project, tically change that ecosystem if it were volved pounding in a row of vertical, the hope is to answer several questions: removed. Beavers tend to live • Will beavers naturally colo- where they have good access nize an area if a BDA is in- to their preferred foods, which stalled? include the bark and twigs of • How effective will different willows, alder, and other de- BDA designs be? ciduous trees, as well as ferns, • Will human installed BDAs grasses, blackberries, aquatic provide winter habitat for plants, and agricultural crops, salmon even if beaver don’t but they’re also pretty adapt- colonize a BDA site? able. They live along rivers • Does the installation of and small streams, in ponds, BDAs improve the survival marshes, and lakes, and even rate of salmon? ditches that have a year-round Trask led us to several water flow. If they don’t have BDAs on one creek, took us deep enough water avail- to see a large natural beaver able, beavers will build dams dam at another location for across a water flow to create comparison, and then took us their own water impound- to see several more installa- ment, using nearby trees. tions on a different stream. Beavers build lodges The results of this BDA in their ponds – mounds of project are mixed, but after branches and logs plastered just nine months and one win- with mud that have underwa- ter, it’s still too early to tell ter entrances. They also dig just how effective they will dens into stream banks, and be. under logs or stumps. Beaver Believers! Beavers breed be- Interest in beavers and tween January and March their impacts on ecosystems and litters of between one and BDAs are constructed by pounding in a row of vertical Douglas has been growing during the eight kits are born between fir posts across a stream, which are then interwoven with last several decades, and has April and June. Kits gener- vine maple or Doug fir limbs. Ideally the BDA will provide really accelerated in the last a prime location for beavers to naturally colonize. ally live with the adults for several years, particularly in two years and then head off to the Pacific Northwest. The mate and start their own colonies. Colo- nine-foot lengths of Douglas fir, rang- search for more ways to effectively re- nies usually contain one breeding pair of ing in diameter from five to 12 inches, store salmon habitat has been one of the adults and recently born kits. across a stream. The posts are then in- main reasons, as fish counts of returning At an average size of 40 pounds, terwoven with vine maple or Doug fir salmonids continue to fluctuate. Water- beavers in Oregon only have a few pred- limbs. Ideally the BDA will catch more ators, including bears, coyotes, and cou- debris flowing downstream, retain more gars. They generally live for five to 10 water, and will provide a prime location years in the wild. for beavers to naturally colonize, and The benefits of beaver dams on maintain the dam the humans started for streams can be profound. Their dams them. slow the flow of water in streams, and At many of the installation sites, cool it down in the process, creating Trask left food caches, constructed cover enhanced habitat for fish and drinking and denning opportunities, and removed water for other species, especially in dry trees to provide sunlight to willow plant- summer months. During heavier winter ings, in order to encourage beaver colo- flows, beaver ponds provide shelter for nization. both adult and juvenile fish. They help Trask explained that prior to control flood conditions during severe the installation of the BDAs, an assess- rainfalls. They also recharge ground wa- ment was made of stream reaches in ter supplies. the region, looking for potential sites. In August 2018 Trask Consult- Those identified sites were then “ground ing was hired by the UNWC to work on truthed” to show evidence of a historical a pilot project to install 27 BDAs on four beaver population in the area. Other cri- different streams in an attempt to en- teria that make good BDA sites include a courage beaver repopulation and influ- series of low terraced stream profiles and Get Your Garden Ready Lawn Care Supplies • Insect Control Trimmer Line • Hoses • Seeds Potting Soil • Garden Tools Family owned & operated for over 45 years 834 Bridge St., Vernonia (503) 429-6364 7 shed councils and conservation groups have focused efforts on improving fish passage in streams by replacing impass- able culverts, but those projects are of- ten very expensive. Recently they’ve been enhancing fish habitat through the placement of large woody debris back into streams, after years of humans pur- posely clearing waterways. The large logs slow the stream flow, create pools and hiding spots for fish, and most im- portantly, capture mobile gravels that lift the stream channel back up to its historic flood plain. There seems to be little ques- tion that beavers, and their dams and ponds, have historically been beneficial for salmon. They obviously have suc- cessfully survived together in the same streams for centuries – a recent bumper- sticker may have said it best – “Beaver taught salmon to jump.” That being said, some wildlife biologists and fish passage experts have retained a healthy skepticism about re- introducing beavers into known salmon bearing streams. Greg Apke is the state-wide Fish Passage Program Coordinator for ODFW who took part in our BDA tour led by Trask. “In my role I get to see projects across the whole state,” said Apke at the start of the tour. “Beaver Dam Analogues have become the new restoration tool, not just here in the Ne- halem basin, but particularly on the east side of the state. We’re seeing hundreds of these being applied. I have a lot of faith in Steve and he has a perspective I don’t have, so when Steve talks, I try to listen. I’m not an opponent, because I continued on page 8
