Elwha Watershed Information Resource

Meadow and forest along the Elwha River. Gary Thayer, National Park Service

Terrestrial ecosystems include areas (such as forests and grasslands) that are important habitat for land-based species. At least 22 such wildlife species (including the bald eagle) feed on salmon carcasses in the Elwha River and subsequently bring nutrients from the salmon back to the terrestrial ecosystems. Currently, salmon numbers are dwindling because the dams on the Elwha River restrict their ability to spawn upriver. Particularly above the dams, declining salmon populations mean reduced food resources for terrestrial species and reduced marine-derived nutrients for terrestrial ecosystems.

The dams (and their reservoirs) have also reduced the amount of terrestrial habitat in the Elwha watershed since they were built in the early 1900s. Currently, the reservoirs occupy 684 acres (National Park Service 1996). It is estimated that most of the current reservoir area was once forested with hardwoods and conifers. Dam removal will restore wildlife habitat and bring nutrients to the river system. It is estimated that 13,000 pounds of nutrients (nitrogen and phosphorus) could be brought back to the Elwha River by returning salmon and steelhead if the dams are removed and the ecosystem is restored (NPS 1996).

Dam removal may have short-term negative impacts for large and small mammals, because increases in turbidity and sediments in the river may temporarily reduce the number of food resources (prey). However, the increases in terrestrial habitat and salmon carcasses brought about by dam removal will potentially have positive long-term effects on all terrestrial species--particularly those that are listed as threatened, endangered, or rare.

The following list includes some of the Elwha wildlife that will benefit from dam removal:

• Bald eagle (Haliaeetus leucocephalus) -- state threatened species
• Cascades frog (Rana cascadae) -- federal species of concern
• Golden eagle (Aquila chrysaetos) -- Washington state candidate species
• Marbled murrelet (Brachyramphus marmoratus) -- federal threatened species
• Northern Goshawk (Accipiter gentilis) -- federal species of concern
• Northern red-legged frog (Rana aurora) -- federal species of concern
• Northern spotted owl (Strix occidentalis caurina) -- federal threatened species
• Pacific fisher (Martes pennanti pacifica) -- federal species of concern
• Peregrine Falcon (Falco peregrinus) -- federal species of concern
• Pileated woodpecker (Dryocopus pileatus) -- Washington state candidate species
• Van Dyke’s salamander (Phethdon vandykei) -- federal species of concern
• Vaux’s swift (Chaetura vauxi) -- Washington state candidate species

Note: Federal species of concern are species at risk of becoming listed because of concerns regarding their status and threats to their existence, but insufficient information is available to list these species. Species on Washington state’s candidate species list are species the state is considering for possible listing at the state level as endangered, threatened, or sensitive.

Researchers are currently collecting information on black bears, small mammals (mesomammals), amphibians, and birds in the Elwha River watershed. These studies will provide baseline data that researchers can use to compare against post dam removal changes in terrestrial habitats and populations.

Three research studies that are gathering baseline information before dam removal are discussed below.

 

Spatial use patterns of black bears in the Elwha River Watershed, Olympic National Park, Washington

Response of riparian wildlife communities to restoration of anadromous fish in the Elwha River Ecosystem

Forecasting avian responses to Elwha River dam removals

Please view the Terrestrial Image Gallery for photographs related to this research.

 

Spatial use patterns of black bears in the Elwha River Watershed, Olympic National Park, Washington

Study Overview: Removal of the Elwha dams and subsequent salmon restoration is expected to result in altered nutrient flow dynamics throughout the Elwha watershed, which may have potentially important effects on Olympic National Park’s black bear population.

In areas where bears and salmon co-occur, bears concentrate along fish-bearing streams to consume salmon. The bears benefit from the influx of energy and nutrients transported to the system by spawning salmon. In turn, bears are important vectors of nutrient transport from marine to terrestrial systems: they feed on salmon runs and subsequently deposit feces and salmon carcasses on land.

To provide baseline information by which to assess the long-term ecological effects of salmon restoration on distribution patterns of bears in Olympic National Park, this study used Global Positioning System (GPS) radio-collars to describe broad-scale patterns in seasonal distribution and movements of black bears prior to dam removal.

Research Activities: Between 2002 and 2005, 18 black bears in the Elwha Valley were captured (16 males and 2 females) and fitted with GPS radio-collars.

Radio-collared black bear. U.S. Geological Survey

Preliminary results indicate that male bears range widely throughout the Elwha watershed during the course of a year and exhibit pronounced seasonal shifts in their use of the Elwha Valley:

• During early spring, males favored low-elevation floodplains, forests and hardwood stands.
• From early to late summer, they favored higher elevation meadows, shrubs and forest stands.
• During fall, males frequently left the watershed--presumably in search of huckleberries on high-elevation mountain peaks.
• By late fall, however, all male and female bears had returned to the Elwha to den.
• Female bears had much smaller ranges than male bears, and they remained at relatively constant elevations throughout the year.

The strongly synchronous pattern of elevation shifts exhibited by male bears across five years provides a baseline for future comparison after dam removal and subsequent salmon restoration. Further, these data have provided the necessary information to design and implement a study using scented, barbed-wire "corrals" to collect hair from black bears along the length of the Elwha River. These hair samples will:

• Allow researchers to describe bear movement patterns further;
• Provide information on numbers of individual bears using the Elwha; and
• Allow researchers to examine dietary sources of carbon, nitrogen, and sulfur (see study synopsis titled "Response of Riparian Wildlife Communities to Restoration of Anadromous Fish in the Elwha River Ecosystem" for further information).

Collaborators:

• John Beecham, Boise, Idaho
• Patricia Happe, Olympic National Park
• Roger Hoffman, Olympic National Park
• Kurt Jenkins, United States Geological Survey--Olympic Field Station
• Kim Sager, United States Geological Survey--Olympic Field Station
• Gerald Wright, University of Idaho

Response of riparian wildlife communities to restoration of anadromous fish in the Elwha River Ecosystem

Study Overview: This project will provide an environmental baseline for monitoring the long-term effects of dam removal and anadromous fish restoration on riparian wildlife communities.

Research objectives:

• Determine occupancy and use patterns of black bears and mesocarnivores (such as mink, otter, raccoon, and skunk) in the Elwha Valley.
• Determine relative distribution or abundance of amphibians (such as Northern red-legged frog) and small mammals (such as white-footed deer mouse) in floodplains and associated wetlands in the Elwha Valley.
• Determine baseline ratios of marine-derived stable isotopes of nitrogen, carbon, and sulfur in selected amphibians and mammals in riparian communities.

Research Activities: Research began in spring 2006 and will continue through fall 2008. During 2006, the researchers accomplished the following field objectives:

• Determining occupancy of mesocarnivores: Twenty-three river reaches were sampled during the summer of 2006, each with three sooted, track-plate boxes designed to record mammal tracks and four cable, hair-snagging devices designed to snag hairs from river otters and beavers. Track-plate boxes and hair-snagging devices were checked five times every third day for 15 days. Visits were made by otters, beavers, striped skunk, short- and long-tailed weasel, raccoon, Western spotted skunk, and Douglas squirrel. In summer 2006, researchers investigated the feasibility of using non-invasive genetic sampling methods to estimate baseline densities of river otters in the Elwha River. See Image Gallery.
• Determining occupancy of black bears and collecting hair samples: Twenty-one barbed-wire corrals were placed along the Elwha River. (Barbed wire corrals are designed to attract bears and snag samples of their hair, serving both to document presence of bears and to collect samples for genetic and isotope analyses.) Samples of 204 black bear hairs were collected during 2006. Currently, researchers are determining the identity of individual bears using the Elwha by genotyping individual hair samples.
• Describing amphibian distribution: Twenty-four 500-meter reaches of Elwha River floodplain were searched to record the presence of amphibian habitats and species.
  • Breeding populations of the Northwestern salamander were found in pools below, between, and above the dams.
  • Northern red-legged frogs were widespread in the floodplain, but only in the post-metamorphic stages.
  • Pacific tree frog larvae were also widespread, though adults were infrequently encountered.
  • Western toads have been found breeding in only two pools in the Elwha floodplain to date.
  • Rough-skinned newt larvae have been found in only two pools in the Elwha floodplain to date.
  • Tailed frogs have been recorded commonly in higher-gradient tributaries of the Elwha River (above clear or likely barriers to fish passage).
  • Olympic torrent salamanders were distributed more broadly in the Elwha drainage than in each of the reaches below, between, and above the dams.

• Describing small mammal distribution: Small mammals were live-trapped for three nights within 12 riparian zone, 500-meter reaches of the Elwha River. The traps captured 375 small mammals (excluding unknown shrews) representing 15 species. Two species of deer mouse accounted for most of the captures: the white-footed deer mouse was captured primarily between and below the dams, whereas the Keen’s mouse was captured primarily above the dams.
• Determining concentrations of marine-derived nutrients: A primary objective of this study is to search for evidence of anadromous fish in the food webs of semi-aquatic and terrestrial wildlife species along the Elwha River. At least three amphibian species (Northwestern salamander, Pacific tree frog, and red-legged frogs) and three mammal species (black bear, river otter, and deer mice) have been selected for the analysis of marine-derived isotope concentrations of nitrogen, carbon, and sulfur in hair or tissue samples. Hairs and tissues of other wildlife species have been collected opportunistically. Soil and vegetation samples have been collected from three riparian plant communities in each river segment. Stable isotope concentrations of soils and vegetation will describe background variation in riparian ecosystems for comparison to trends observed in wildlife tissues.

During 2007, researchers will continue research on each of the 2006 objectives. In addition, they plan to extend sampling to a reference river system--the East Fork of the Quinault.

Collaborators:

• Michael Adams, United States Geological Survey
• Nate Chelgren, United States Geological Survey
• Patricia Happe, Olympic National Park
• Brian Hauge, Peninsula College
• Kurt Jenkins, United States Geological Survey
• Kim Sager, United States Geological Survey
• Steven Perakis, United States Geological Survey

Forecasting avian responses to Elwha River dam removals

Study Overview: This project is investigating bird species distributions, habitat use, and species numbers in the Elwha watershed prior to dam removal.
Few dam removals have received comprehensive ecological study, and fewer still have considered effects on associated terrestrial components. There are six stages in this project to determine avian responses to pending Elwha dam removals:

• Establishing a pre dam removal inventory;
• Modeling species densities and distributions;
• Forecasting post dam removal habitat distributions and conditions;
• Forecasting species responses to changing post removal conditions;
• Monitoring post removal responses; and
• Evaluating consistencies and discrepancies between actual and forecasted responses.

Research Activities: The first four stages of the project are underway. A pre dam removal avian inventory was completed during the 2006 breeding season. Using the variable circular plot protocol implemented in several Pacific Northwest parks, 269 plots were sampled and 1830 birds (representing 42 species) were detected. Total avian densities were lowest (8.4 birds per hectare) in low elevation shrubs and greatest (10.0 birds per hectare) in western hemlock forests. Total avian densities in all habitats sampled exceeded values obtained in the 2002-2003 avian inventory of Olympic National Park, suggesting that the Elwha riparian zone supports regionally high population densities.

Three scenarios have been developed to forecast avian responses to post removal habitat changes. These scenarios apply models with constraints at local, patch, and landscape scales:

• The first assumes each species is limited by habitat only: restored habitats will be colonized rapidly at densities similar to existing habitats of the same type.
• The second adds effects of habitat area on species occupancy and density.
• The third includes landscape context by assuming colonization will be constrained by dispersal from existing habitats.

This series of forecasts should bracket actual responses, which will be monitored as restoration proceeds (the last two stages).

Collaborators:

• Carly Gelarden, Western Washington University
• John McLaughlin, Western Washington University

Reference

National Park Service. 1996. Elwha River Ecosystem Restoration, Draft Environmental Impact Statement. National Park Service, Olympic National Park, 600 East Park Avenue, Port Angeles, Washington, 98362.

Additional Information

Jenkins, K. J., S. L. Roberts, and D. E. Seaman. 2005. Monitoring small mammal populations in coniferous forest ecosystems of Olympic National Park: Preliminary assessment. U. S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Olympic Field Station, Port Angeles, WA. Download.

Jenkins, K. J., A. Woodward, and E. Schreiner. 2003. A framework for long-term ecological monitoring in Olympic National Park: Prototype for the coniferous forest biome. U. S. Geological Survey. Download.

Olympic Peninsula Audubon Society.