North Cascades National Park Service Complex at-risk terrestrial wildlife species: Focused condition assessment 1995–2020

Ransom, Jason; Rine, Kristin; Christophersen, Roger; Hansen, Michael; Antonova, Natasha; Braaten, Anne; Whiles, Logan; Akins, Jocelyn; Schaming, Taza; Rochefort, Regina

doi:10.36967/2299559

The North Cascades Ecosystem is one of the largest and most intact wilderness areas in the contiguous United States. It spans 34,965 km2 across the U.S.-Canada border between central Washington State and southern British Columbia and is bisected north to south by the Cascade Mountain range. The North Cascades National Park Service Complex (hereafter, the Park) lies in the heart of the ecosystem and is comprised of North Cascades National Park (2,044 km2), Ross Lake National Recreation Area (NRA) (473 km2), and Lake Chelan NRA (251 km2). The large wild landscape of the Park is bisected east-west by the North Cascades Highway (Washington State Route 20), which is paralleled by a large electric transmission corridor connecting to hydroelectric power stations and dams in the Skagit River watershed at Gorge, Diablo, and Ross reservoirs. Additional infrastructure throughout the Skagit River corridor and Stehekin Valley includes campgrounds, visitor centers, and housing, as well as the Environmental Learning Center, a developed campus adjacent to Diablo reservoir. The trail system in the Park includes 560 km (348 mi) of hiking trails, along with several climbing and mountaineering routes. Over 75 mammal species, >200 bird species, 27 fish species, and 17 reptile and amphibian species share this ecosystem, along with >2600 plant and fungus species. This report focuses on terrestrial wildlife species in the Park that are federally listed under the Endangered Species Act of 1973 (ESA), state-listed under Washington Administrative Code, and/or designated by NPS as Management Priority species. We provide a detailed synthesis of information around NPS records from 1995–2020 for nine bird and nine mammal species and one mammal Order (Chiroptera [bats]), as well as a suite of invertebrate pollinators in the Park where data are available. Information for each species includes life history information, occurrence in the Park, protective status, trends when known, a summary of known threats, and a summary of conservation and research needs. We also provide brief summaries for an additional five bird and two mammal species, and one taxa group (woodpeckers) where data are more limited. Terrestrial wildlife species in the Park are potentially susceptible to a variety of threats, ranging from climate change impacts to habitat and behavior (e.g., changes to temperature, precipitation, phenology of resources, competition), atmospheric deposition of nutrients (e.g., nitrogen, phosphorus, sulfur) and pollutants (e.g., ozone, methylmercury, microplastics, other bioaccumulative toxins), disease (e.g., avian influenza, West Nile virus, white-nose syndrome), to direct impacts from human presence (e.g., infrastructure, recreation, direct killing). Many of these threats can affect presence, distribution, and survival of wildlife species and populations in the ecosystem. Anthropogenic threats to terrestrial wildlife include pollutants and contaminants to air, water, and natural sounds. Water quality is generally good in the Park, but atmospheric deposition contributes a variety of contaminants, as does leaching from old mines and other ground-based sources. Water impoundment and water-level manipulation are also known to influence bioaccumulation pattern, trophic transfer, and health risk of some heavy metals in food webs. Air quality in the Park is also generally good, but deteriorates when westerly winds transport pollutants from developed areas along Puget Sound, as well as with smoke from wildland fires. Noise pollution is variable across the Park, and anthropogenic noise (typically aircraft, watercraft, and automobiles) registered 11–59.3% of time across three sites in 2015. Such noise was most often in the 35 dBA range but was recorded as high as 52 dBA at two sites. Terrestrial wildlife responses begin at noise levels of approximately 40 dBA, and most often are reported for species that rely on vocal communication, such as birds. Emergence and transmission of disease is a persistent threat to wildlife species, and in some cases directly relates to human activities and connectivity of wildlife populations. Thousands of known viruses are currently circulated among wild mammals, and climate change is expected to inflate the rate of transmission across species. Wildlife diseases known to occur in the Pacific northwest include, but are not limited to: avian influenza, West Nile virus, rabbit hemorrhagic disease in lagomorphs, hoof disease, bluetongue virus, and chronic-wasting disease in ungulates, parvovirus in canines and mesocarnivores, Mycoplasma ovipneumoniae (pneumonia) in wild sheep and goats, white-nose syndrome in bats, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in multiple taxa but especially acute cases in felines and mustelids. Diseases will likely continue to emerge through time and the effects of their occurrence on populations may be difficult to detect. Human activities and infrastructure can also directly impact wildlife species in the Park. Infrastructure associated with the Skagit River Project originally inundated 50 km2 of wildlife habitat in what is now Ross, Diablo, and Gorge reservoirs. The reservoirs now provide nesting habitat for bald eagles and osprey, as well as provide important migratory stopover habitat for waterfowl, such as western grebe. These reservoirs also likely affect microclimates, influence riparian habitat with fluctuating pool levels, contribute to erosion of terrestrial habitat, accumulate heavy metals and microplastics, and may limit the ranges of some terrestrial species within the Park. The operation of the dams also influences downstream hydrology on the Skagit River, with direct implications on salmon production and consequent winter food availability for piscivorous species such as bald eagles. Throughout the Skagit River corridor, hydroelectric infrastructure, NPS infrastructure such as campgrounds and facilities, and the Environmental Learning Center all emit artificial lights which can disrupt migration and travel of birds, including marbled murrelet. Transmission lines and power stations along the Skagit also introduce the threat of bird strike and electrocution. Recreation is known to affect wildlife in a variety of ways, including impacts on physiology, behavior, and demographics (decreased survival and reproduction) at both the individual and population level. Annual visitation to the Park has increased dramatically in recent years, with an estimated 982,000 visitors in 2020. Most visitors to the Park arrive on developed roads. The impacts to wildlife from developed roadways include potential disruption of wildlife travel, habituation and/or toxicity from road deicers and automobile byproducts, impacts to reproduction from noise, and death from vehicle strike. In summer 2020, traffic counters logged 255,582 vehicles travelling into the Park from the west and 147,460 vehicles travelling into the Park from the east on the North Cascades Highway. Most vehicular strikes to wildlife are not documented, but from 1995–2020, NPS and Washington Department of Transportation documented individuals of at least 16 species killed in the Park. The most commonly detected carcasses were black-tailed or mule deer, likely due to their conspicuous size, but other mammal species detected included black bear, bobcat, coyote, and porcupine. Bird species were also detected dead on the road, including hawks, owls, grouse, and common raven. Impacts of roads on wildlife in the Park are largely unquantified and represent an important need for future research. Direct killing of wildlife during European settlement of the North Cascades severely impaired the ability of some species to persist through time. From 1826–1867, The Hudson’s Bay Company shipped >50,000 carnivore skins from around the North Cascades Ecosystem, including 15,350 gray wolves, 11,187 Canada lynx, 1,249 wolverine, 8,706 red fox, 12,464 fisher, and 3,188 grizzly bear. This ultimately resulted in extirpation of some species, like fisher and grizzly bear, with other species remaining very rare today. Purposeful direct killing of wildlife in the Park today is limited to licensed hunting of some species (typically deer and black bears) in Ross Lake NRA and Lake Chelan NRA, which includes traditional use by local Tribes. Illegal killing of wildlife (poaching) does occur intermittently. Wildlife species may also be euthanized by Park managers as a last resort during conflict management operations. The management and conservation of wildlife in the Park is mandated by the NPS Organic Act of 1916, with guidance on protection, recovery, and stewardship of at-risk species provided in NPS Management Policies. Regulatory protections for Park wildlife are established in the Code of Federal Regulations, with authority granted to the Park Superintendent to establish supplemental protections through the Park Superintendent’s Compendium. Examples of statutes included in these supplemental protections are the authority to implement short-term public closures for wildlife protection, which may include active nest or den sites, or situations where public safety is of concern (e.g., a large predator with prey on a trail or near a campsite), prohibition of artificial lights for wildlife viewing or hunting, prohibition of trapping, requirements for use of bear-resistant food storage containers, and regulations pertaining to use of pack animals and dogs. The Park Wildlife Program guides the focus of wildlife monitoring and research conducted by NPS staff and implements management actions. These actions require consultation with the U.S. Fish and Wildlife Service regarding ESA-listed species, and with Washington Department of Fish and Wildlife regarding state-listed species. The mission of the Park Wildlife Program is “protect, conserve, and restore wildlife species and their habitats through an ethic of stewardship that values the well-being of individuals, populations, and communities. The [Park] Wildlife Program will provide scientific leadership, scholarship, and active collaboration with partner agencies, Tribes and First Nations, and non-governmental organizations, toward stewardship of wildlife resources at an ecosystem scale, in a paradigm of continuous change that is not yet fully understood, based on best available science, accurate fidelity to the law, and with consideration of the diverse cultural values of humans that share the North Cascades Ecosystem”. Throughout this report, needed conservation actions are presented by species. A reference table of best practices and required mitigations for management activities around wildlife is also presented.

North Cascades National Park Service Complex at-risk terrestrial wildlife species: Focused condition assessment 1995–2020

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