17 Years of Restoration to Rebuild Our Small but Mighty Prairie
- Emily Evans
- Jul 10, 2024
- 6 min read
By Amy Porter, Director of Conservation
Published in Wolf Tracks vol. 41, no. I
When Wolf Haven International was established in 1982, the surrounding prairie was buried under a dense swath of Scotch broom. At the time, Wolf Haven’s role in conservation efforts did not extend beyond wolves, but grander visions were on the horizon. In 1987, 50 acres of land adjacent to the wolf sanctuary was being scoped by developers with interests in subdividing it into five-acre plots for housing. Fortunately, Wolf Haven was able to purchase all 50 acres to ensure a peaceful buffer remained around the wolves. Now, in addition to our wolf sanctuary, Wolf Haven’s acreage includes 36 acres of Mima mound prairie, 8 acres of oak/conifer woodland, and 8 acres of wetlands. This mosaic of habitats makes up the Patrick Vance Dunn Memorial Prairie.
Historically, western Washington’s prairie landscape covered over 150,000 acres. Sadly, 97% of those prairies were lost to fire suppression and land conversion to agriculture and development. And of the 3% of prairie habitat that remains, only 1% is considered in good condition. Furthermore, remnant prairie parcels are relatively small, fragmented, and often cannot support populations of target conservation species.
Wolf Haven’s prairie is part of the historic Rocky Prairie, located just ¼ mile from Rocky Prairie Natural Area Preserve to the north and West Rocky Prairie Wildlife Area to the west. This spatial relationship means our prairie is an important connector for species like western bluebirds and butterflies that require movement between neighboring preserves.
In 2007, intensive efforts to rebuild a native community of prairie plants and animals began at Wolf Haven. Many partners, including Center for Natural Lands Management (CNLM), Ecostudies Institute, Washington Department of Fish & Wildlife, U.S. Fish and Wildlife Service, and the U.S. Department of Defense have helped us nurture our prairie into a vibrant ecosystem thriving with life. Restoration efforts have included an integrated system of prescribed fires, invasive species control, direct seeding, and plug planting of native prairie species that continue to this day.
South Puget Sound prairies are adapted to regular, low-intensity fires that were historically maintained by indigenous peoples. In the absence of fire, Douglas fir and other non-native plants and grasses quickly encroach and overwhelm prairie ecosystems. Prescribed fire helps prevent conifers from taking over and removes accumulated moss, thatch, and invasive species that crowd out native species.
Prescribed burns were reintroduced to our prairie in 2008, and approximately six acres are burned annually. No more than 20% of the prairie is burned in a year to ensure adequate refugia for wildlife. Fire rotation has followed a four to seven year cycle and by 2021, two complete iterations of burns were completed. Fall rains typically follow the burn season and come with a flush of vegetation, comprised mostly of non-native grasses and forbs that germinate aggressively and sprout before native plants. Herbicides are applied following burns to remove non-native species, then the ground is seeded with native bunchgrass, Idaho fescue, and native prairie forbs.
Scotch broom is a common threat on many prairies. It alters the structure of prairie habitat by creating uniform woody and shrubby stands that outcompete most native species. The Scotch broom invasion on our prairie was initially addressed by mowing, but in 2009, efforts shifted to a system that used prescribed fire, chemical spot sprays, brush cutting, and hand pulling. By 2014, chemical sprays were no longer required and Scotch broom has since been controlled entirely by prescribed burns and hand pulling.
Invasive grasses, such as tall oat grass, rattail fescue, and bent grass are also problematic. Tall oat grass forms dense mats that smother native plants and prevent their establishment. Rattail fescue and bent grass fill in the spaces around native bunch grass and forbs and diminish bare ground, which is essential for ground nesting bees and many butterflies who lay their eggs at the bases of plants. Bare ground also provides important habitat for larval basking and thermal regulation. Since 2011, a selective herbicide that attacks non-native grasses without damaging native bunchgrass and forbs has been applied at Wolf Haven. The results: tall oat grass was essentially eliminated but rattail fescue and bent grass still require attention.
Knapweed, a noxious weed that grows in uniform patches, also infested a portion of our prairie for a while. From 2011-2014, over 300 plants were removed by hand annually. Fortunately, with time, fewer plants were found and by 2020, less than 10 plants are removed annually.
The area around the visitor entrance was once the site of an old homestead and was infested with invasive species like Vinca major (a spreading, vine-like plant) and large black locust trees. The Vinca infestation was chemically treated and essentially eradicated and the black locust trees were removed and burnt. In 2015, 200 oaks were planted in their place.
The oak habitat at Wolf Haven has been a top priority because once lost, oaks take centuries to regenerate. Our oaks were released from extensive Douglas fir encroachment by removing and girdling the firs. Girdling strips the bark around the trunk and the damage disrupts the flow of nutrients, killing the tree without felling it. The remaining snag supports cavity nesters, like western bluebirds, purple martins, woodpeckers, owls, and small mammals.
Another top priority has been enhancing pollinator habitats with plants like golden paintbrush. Considered the jewel of the prairie, golden paintbrush is an important resource for bumblebees. In 1997, it was listed as threatened under the Endangered Species Act due to the loss of prairie habitat. At the time of its listing, only 10 populations remained in the Pacific Northwest with fewer than 20,000 plants.
Restoration of golden paintbrush on our prairie began in 2007. Initial efforts involved planting 920 nursery grown plugs. Unfortunately, plug establishment proved challenging because ravens constantly uprooted them. In 2010, efforts shifted to direct seeding into areas burned in the fall prior to planting. The combination of burning and the shift to seeding resulted in a flourishing golden paintbrush population, growing from 1,430 flowering plants in 2013 to 9,112 in 2018!
In 2019, numbers dropped significantly, but this decline was seen throughout the region. Population numbers continued to fluctuate with cycles of slight rebounds and declines. Rattail fescue invasion is considered a possible culprit to recent declines, but with increasing invasive grass removal and native plantings, we are hopeful our population will steadily rebound. From 2022-2023, our golden paintbrush population grew from 1,872 to 2,900 flowering plants.
In addition to golden paintbrush, 60,000 plugs and 194 pounds of seed representing 78 prairie species (many of which are important butterfly nectar sources and larval host plants) have been planted within the burn footprints on Wolf Haven’s prairie. Wild seeds are hand-collected by volunteers, cleaned, and propagated at Shotwell’s Landing, then returned to surrounding prairies. CNLM provides the bulk of our seeds via their conservation nursery program, which yields much higher quantities than is possible from hand-collecting wild seeds.
In 2018, ribwort plantain was included in our seed mixes. While this plant is non-native, it’s a host plant for the federally endangered Taylor’s checkerspot butterfly and must be established for a site to be considered for reintroduction. Our prairie is now considered a candidate site for future checkerspot release, which is expected to occur within five years. Hoary elfin, valley silverspot, and Puget silverspot butterflies are also conservation targets and were all recently observed at Wolf Haven.
The regionally endemic and federally threatened Mazama pocket gopher thrives on our prairie as well. From 2005-2008, 193 individuals were captured from sites slated for development and translocated to our prairie. The last population survey in 2015 reported 600 individuals.
Bat surveys began in 2011 and revealed the area around our visitor center was a hot spot for activity. In 2012, 10 bat boxes were installed and little brown and Yuma bats moved in almost immediately. After just a few years, a full-fledged colony was present. In 2023, 514 bats were counted using the boxes. Acoustic monitoring has also confirmed the presence of several other species using the area.
At least 54 bird species call our prairie home, including the migratory western bluebird, which began disappearing from oak-prairie habitats in the mid-1900s. Habitat loss was a major factor in the species’ decline, but more important was the loss of tree cavities. In 2017, seven bluebird boxes were installed around the prairie. The boxes have supported several successful nesting events that produced 16 fledglings.
Due to the strategic restoration and land management actions by many dedicated and passionate people, our small but mighty prairie is now considered one of the best examples of effective prairie conservation in the region! If you are interested in learning more, or supporting Wolf Haven's prairie restoration efforts, please email prairie@wolfhaven.org or watch our short 20-minute Promise for the Prairie documentary on YouTube.
