Northwest Science 97: Accepted articles
Potential Nutritional Effects of Missed Feedings to Marbled Murrelet (Brachyramphus marmoratus) Chicks due to Disturbance - Suzanne L. Nelson, Katherine Fitzgerald
The marbled murrelet is a federally threatened seabird that continues to decline throughout its range. Murrelets utilize late-successional and old growth coastal forest as nesting habitat, and forage in the marine environment. Murrelet adults invest heavily in raising a single young per year, and chicks are dependent on adults for all their nutrition during the 27- to 45-day nestling period. Rates of nestling growth and development are highly sensitive to food quality and quantity. We developed a nutritional model that examines the effects of disturbance that result in missed feedings for murrelet chicks. Six dietary scenarios were developed to simulate murrelet chick feeding; a high quality, intermediate, and low quality diet, and one or two feedings were missing from each diet. Five of the six scenarios resulted in insufficient calories for marbled murrelet chicks, with only the high quality diet able to provide sufficient calories with one missed feeding. The intermediate and low quality diets with missed feedings were not able to meet the metabolic requirements of the developing chick, and over time would result in growth stunting and starvation. Future conservation actions should focus on avoiding disruptive activities at places and times when adult murrelets are likely to be engaged in meal deliveries to chicks, and on improving forage conditions for murrelets.
Patterns of Prairie Soil Preference and Occupancy for the Threatened Mazama Pocket Gopher in Washington – Suzanne L. Nelson, Michael C.T. Carlson
Mazama pocket gophers (Thomomys mazama) act as ecosystem engineers and are keystone species on the remnant glacial prairies of the southern Puget Sound lowlands. Three subspecies of Mazama pocket gophers are regionally endemic to Thurston County, Washington, and were federally listed as threatened in 2014. We examined patterns of occupancy and habitat and differences between subspecies for soil type preference. In total, 1,241 Mazama pocket gopher surveys, comprising approximately 4,654 hectares, resulted in 165 occupancy sites. Pocket gophers were detected more often on sites with more preferred soils than on less preferred soils (p < 0.01), though there were differences in occupancy rates between subspecies. Soil type and availability can act as surrogates of gopher habitat availability. Such quantification of habitat availability and potential loss is important given the absence of population estimates. Therefore, the conservation of undeveloped lands with soils identified a priori as preferred is necessary for both the recovery and continued persistence of Mazama pocket gophers.
Scanning the horizon for potential nonnative aquatic plant and algae arrivals to the Pacific Northwest – SOTS 2022 – Katherine E. Wyman-Grothem, Theresa A. Thom, Heidi L. Himes
To date, the Pacific Northwestern United States has experienced fewer nonnative species introductions than other parts of the country, presenting an opportunity to minimize future harm from invasive species by investing in prevention efforts. Horizon scanning for potential future invasive species provides foundational data for developing efficient prevention and early detection strategies. We gathered more than twenty Federal, State, Tribal, local government, University, and industry partners to provide input on priority geography, introduction pathways, and taxa for a horizon scan focused on the Pacific Northwestern United States. The scope of this initial effort included submerged or floating aquatic plants and algae that could be introduced to the region via movement of recreational boats. Watercraft inspection data were combined with climate matching analyses to identify “top donor regions” from which submerged or floating aquatic plants were most likely to arrive. We identified five aquatic plants as posing high risk to the Pacific Northwest on the basis of climate match and prior history of invasiveness in other locations: Carolina mosquitofern (Azolla caroliniana), crested mosquitofern (Azolla cristata), Indian swampweed (Hygrophila polysperma), wingleaf primrose-willow (Ludwigia decurrens), and water spangles (Salvinia minima). Another 21 species pose uncertain risk given available information. These results can be used to inform regulatory actions, improve training, and refine detection tools and strategies on a local, regional, and national level. More broadly, this horizon scan provides a template for future horizon scanning for other geographies, pathways, and taxonomic groups.
Comparison of Gravimetric and Volumetric Methods to Estimate Brook Trout (Salvelinus fontinalis) Fecundity – Science of the Service 2022 – Nolan P. Banish
Estimating fish fecundity is important for developing accurate population models and informed management decisions. Fecundity can be determined by tedious, complete oocyte counts. Researchers save time by counting a subsample of oocytes, measuring the subsample and total ova volume and weight, and extrapolating to produce fecundity estimates using volumetric and gravimetric methods. Volumetrically and gravimetrically generated fecundity estimates from 70 brook trout (Salvelinus fontinalis [range 143–356 mm]) captured from Long Creek, Oregon, were compared to total oocyte counts to evaluate the accuracy and precision of each method. The average total oocyte count was 775 (SD + 354.8). The mean difference between total oocyte count and extrapolated count based on the gravimetric method was 111.2 (SD + 154.0) and 165.9 (SD + 279.0) for the volumetric method. Gravimetric and volumetric fecundity estimates were closely correlated with total oocyte counts, although both were positively biased. Volumetric estimates were on average 1.100 times true fecundity (95% CI = 1.05, 1.15) and gravimetric estimates were 1.086 times true fecundity (95% CI = 1.05, 1.12). The gravimetric estimation method was less biased than the volumetric method and this bias should be weighed in management decisions that require accurate fecundity estimates.
Human and wildlife use of mountain glacier habitat in western North America – Scott Hotaling, Jordan Boersma, Neil A. Paprocki, Alissa Anderson, Logan Whiles, Lucy Ogburn, Sophia Kasper, Catharine White, Daniel H. Thornton, Peter Wimberger
The global recession of glaciers and perennial snowfields is reshaping mountain ecosystems. Beyond physical changes to the landscape and altered downstream hydrology, the implications of glacier decline for biodiversity are poorly known. Before predictions can be made about how climate change will affect wildlife in glacier-associated ecosystems, a more thorough accounting of the role that glaciers play in species’ life histories is needed. In this study, we deployed an elevational transect of wildlife cameras along the western margin of the Paradise Glacier, a rapidly receding mountain glacier on the south side of Mount Rainier, WA, USA. From June to September 2021, we detected at least 16 vertebrate species (seven birds, nine mammals) using glacier-associated habitats over 770 trap nights. Humans, primarily skiers, were the most common species detected, but we also recorded 99 observations of wildlife (birds and mammals). These included three species of conservation concern in Washington: wolverine (Gulo gulo), Cascade red fox (Vulpes vulpes cascadensis), and white-tailed ptarmigan (Lagopus leucura). Collectively, our results reveal a rich diversity of wildlife using a single mountain glacier and adjacent habitat in the Pacific Northwest, emphasizing a largely overlooked risk of climate change to mountain biodiversity. We conclude by highlighting the global need for similar studies to better understand the true scale of biodiversity that will be impacted by glacier recession in mountain ecosystems.
Bull Trout Passage at Beaver Dams in Two Montana Streams – J. Marshall Wolf, Niall G. Clancy, Leo R. Rosenthal
Beaver (Castor canadensis) translocation and mimicry is an increasingly popular set of tools for process-based restoration of degraded streams. Previous studies indicate that spring-spawning salmonid fishes can pass beaver dams in higher proportions than fall-spawning species. Thus, restoration or mimicry of beavers in streams containing threatened, fall-spawning Bull Trout (Salvelinus confluentus) is of concern to many biologists. We evaluated Bull Trout passage at beaver dams in two Montana streams: Meadow Creek (East Fork Bitterroot River drainage) in summer 2020 and Morrison Creek (Middle Fork Flathead River drainage) from 1997 to 2011. In Meadow Creek, 16% of PIT-tagged Bull Trout which entered a large beaver dam complex were detected upstream of some dams, but no fish moved through the entire 1 km complex. The redds in Morison Creek occurred below beaver dams in higher proportion than if random spawning-site selection had occurred. Redds were found above some beaver dams during all 9 years they were present. These results suggest that beaver dams can affect the movement of Bull Trout and that passage depends on the characteristics of individual dams and reach geomorphology. Our methods cannot distinguish between inhibition of fish movement and selection of beaver-created habitats by fish due to the limited data we had on spawning habitat. Therefore, we suggest future research on beaver restoration in streams with Bull Trout be carefully monitored and conducted in an adaptive framework. Comparing spawning-site selection and fish movement in streams with and without beaver may provide additional information.
Geoarchaeological Record of the AD 1700 Earthquake and Tsunami at the Salmon River Wet Site, Central Oregon Coast – Rick Minor, Alan R. Nelson
Coseismic subsidence is a major contributor to the scarcity of evidence in the archaeological record of prehistoric earthquakes along coasts of the Cascadia subduction zone. The stratigraphy of suddenly subsided tidal wetlands, in places overlain by tsunami-deposited sand, records a long history of great (magnitude 8–9) earthquakes over the last 3000–7000 years. The most recent of these great earthquakes and its accompanying high tsunami occurred on January 26, 1700. Here we synthesize geologic and archaeological investigations in the Salmon River estuary on the central Oregon coast. Following coastal subsidence of 1.4 ± 0.4 m during the AD 1700 earthquake, the site of a prehistoric settlement was submerged and covered by tsunami sand and tidal mud, creating an archaeological “wet site” subject to erosion in the tidal zone. Excavations in the last remnants of the eroding cultural deposits recovered evidence of a Tillamook Indian hunting camp occupied within a few hundred years before the AD 1700 earthquake. The Salmon River Wet Site, and similar submerged archaeological deposits in other estuaries, constitute rapidly disappearing evidence of coseismic subsidence during the AD 1700 earthquake along the Cascadia subduction zone on the north Pacific coast.
Northwest Science 96: Accepted articles
Non-breeding-season Site Fidelity and Evidence of Migration of Steller Sea Lions (Eumetopias jubatus) - Grey W. Pendleton, Lauri A. Jemison
Most research that has been done regarding Steller sea lions (SSLs; Eumetopias jubatus) has been during the breeding season. Adult SSLs are known to have high among-year breeding-season site fidelity, typically with movement away from breeding-season locations during non-breeding seasons. Using non-breeding-season sighting data of permanently-marked SSLs from four areas in Alaska and more broad-scale breeding-season sightings, we estimate among-year non-breeding-season site fidelity (i.e., the probability a SSL moves from its breeding season location to a specific non-breeding-season area). Some SSLs, especially females, have high site fidelity to non-breeding-season areas; fidelity is markedly lower for males. We found no evidence that site fidelity varied among natal rookeries, but our sample sizes are relatively small, possibly limiting our ability to determine such effects. With our estimates of non-breeding-season site fidelity, coupled with previously demonstrated breeding-season site fidelity, we conclude that SSLs should be considered to be partial migrants (i.e., migratory behavior exhibited by only some individuals in a population) with at least some individual SSL, particularly females, exhibiting migratory behavior.
Long-term Monitoring of Rocky Intertidal Communities: Lessons and Implications from the Redwood National and State Parks, Northern California - David Lohse, Karah N. Ammann, Eric C. Dinger
A challenge modern-day ecologists and resource managers face is how to separate natural variations in populations from changes caused by human activities (e.g., climate change). Long-term monitoring programs provide valuable information to assist in this endeavor. This study details the initial findings of a long-term monitoring program initiated in 2004 to monitor changes in rocky intertidal communities within Redwood National and State Parks (RNSP), located in northern California. Permanent plots were established at three sites using protocols developed by MARINe (Multi-Agency Rocky Intertidal Network), a consortium that monitors rocky intertidal communities along the western coast of North America. Replicate plots were set-up to monitor changes in abundance of key intertidal taxa, including mussels (Mytilus californianus), barnacles (Chthamalus dalli and Balanus glandula), red alga (Endocladia muricata), and rockweeds (Pelvetiopsis limitata and Fucus gardneri). Plots have been sampled annually since they were established. Results from the first 15 years of this study indicate that all taxa exhibited substantial short-term (annual) variation, with barnacles and Endocladia exhibiting the most. For barnacles, such variations were correlated with measures of recruitment. Except for Pelvetiopsis, all other target taxa experienced at least one period of large-scale major change, where abundances decreased dramatically (> 50%) simultaneously in most plots. However, in almost all cases abundances recovered, resulting in no apparent long-term changes. For the few instances where long-term changes were detected, it is possible this result may be an artefact of the analytical methods used to assess them. The potential implications of this finding are discussed.
Evidence of Bumble Bee Extirpation and Colonization, Galiano Island, British Columbia, Canada - Andrew D. F. Simon, Lincoln R. Best, Brian M. Starzomski
We present evidence for historical change in a bumble bee community on Galiano Island, British Columbia, Canada, including the probable extirpation of three bumble bee species—Bombus insularis (Smith, 1861), B. occidentalis Greene, 1858 and B. suckleyi Greene, 1860—as well as the disappearance of two species represented by singletons in the historical record: B. fervidus (Fabricius, 1798) and B. flavidus Eversmann, 1852. Evidence is based on a comparison of historical and contemporary species occurrence data, including recent data from intensive sampling targeting bumble bees using blue vane traps. The decline of B. occidentalis in southern portions of its range has long been observed, yet to our knowledge this is the first established case of its probable extirpation within an extensively surveyed part of its range. Results indicate that an additional species, B. vosnesenskii Radoszkowski, 1862, which has been expanding its range in the wake of the decline of B. occidentalis, may be a recent arrival on Galiano Island. Elsewhere in the region, B. vosnesenskii has become a dominant species, particularly in urban environments. However, our data show it to be the least abundant species on this largely forested island. We also report patterns in the occurrence of B. sitkensis Nylander, 1848 and B. vosnesenskii suggesting that niche segregation may confound the effect of competitive exclusion previously reported for these species. Potential factors contributing to this likely case of bumble bee extirpation and subsequent colonization are discussed in the context of Galiano Island’s historical land use and ecology. In conclusion, we assess the potential for community science to aid in the detection of ecological change via comparison of historical baseline and contemporary crowd-sourced biodiversity data.
A Decade of Understory Community Dynamics and Stability in a Mature Second-growth Forest in Western Washington – Ida Rex, Dylan G. Fischer, Ryan Bartlett
It is often assumed that dominant forest understory communities are predictably associated with overstory tree species, yet several long-term studies suggest that understory communities are more independent of overstory change. We use a 10–year dataset to explore variation in understory communities in a mature second-growth temperate forest in Western Washington. We classify all recorded species into six growth-forms (graminoids, ferns, shrubs, subshrubs, saplings, herbaceous species), and introduced species, (collectively grouped) to analyze responses to overstory productivity, stand age, canopy heterogeneity, soil type, stand type, and proximity to a canopy-gap forming pathogen (Phellinus weirii), as well as overstory C changes though the decade. Plant diversity and cover declined marginally through time (Shannon’s H’ declined by 8%; and cover by 4.5%) as plots remained dominated by clonal species Polystichum munitum and Gaultheria shallon. Species richness decreased significantly by 23% between years (mean plot richness 10.02 in 2008 to 8.05 in 2018), and diversity, sub-shrubs, and shrubs generally declined with stand age. Shrubs were more abundant in conifer dominated plots. Ferns, and changes in ferns, were associated with presence of P. weirii, where cover increased in infected plots. Ordination results suggested community composition was correlated with changes in canopy cover (conifer forests) and stand age (deciduous forests). Changes in total plot C and canopy cover were also associated with diversity and total cover. Nevertheless, our results support incremental changes in understory communities on decadal time scales and limited predictability of the understory based on the overstory.
Bee Community Differences Among Urban and Rural Sites in Oregon’s Willamette Valley – Briana C. Lindh, Annie Jolliff, Samantha Coleman, Marceline Skelton, Olivia Mack, Molly Hansen
We explored differences in bee communities between urban sites in the city of Salem and nearby rural sites with restored areas. While cities provide habitat for some wild pollinators, urban bee communities tend to exhibit different composition than rural ones, with urban communities particularly lacking ground-nesting and specialist oligolectic bees. We wanted to know whether these differences would still be present in a small city that is set in a heavily degraded rural landscape. We expected that bees with narrow diet breadth would primarily use native floral resources. We found that urban and rural sites exhibited distinctly different bee community composition, both in 2018 and 2019. The rural indicators matched our predictions, but there were some surprising large-bodied ground nesters present in the city. The Bombus and Lasioglossum species that were the major drivers of the urban-rural differences were primarily associated with exotic plants in rural areas. Extreme specialist bees that used only one native plant genus were present only in rural restoration sites, but their numbers were too small to generate statistically significant patterns. Our results suggest that rural and urban land managers should be aware of the importance of the mass of floral resources provided by exotics and of the crucial importance of certain native plants that host specialist bees.
Classification and Assessment of Riparian Ecosystems in Northwest Oregon for Restoration Planning – Steven A. Acker, Gordon H. Reeves, Johan B. Hogervorst, Brett Blundon, Ian-Huei Yau, David M. Bell
Riparian ecosystems are a critical ecological component in the Pacific Northwest. Many have been altered by human activities and need restoration. Establishing restoration objectives is daunting because of inherent spatial and temporal variation of geomorphology, disturbance regimes, and vegetation. We developed an analytical framework using geology and climate as the template for natural disturbance processes influencing riparian vegetation in northwest Oregon. We identified three ecoregions with contrasting geology and climate: Coast Range, dissected topography and rain-dominated hydrology; Western Cascades, dissected topography and rain- and snow-dominated hydrology; and High Cascades, undulating topography and snow-dominated hydrology. For all three, the most abundant stream reach type was small (< 15 m channel width) with wildfire the predominant natural disturbance. However, reaches affected by geomorphic disturbance were common for the Coast Range and West Cascades. Riparian vegetation dominated by large trees (≥ 51 cm diameter) is underrepresented compared to reference conditions for the Coast Range and West Cascades. Variation between subbasins in departure of current from reference conditions is greatest in the West Cascades and negligible in the High Cascades. Vegetation in the Coast Range has moved in recent decades towards reference conditions. Wildfires since the latest remote-sensing-derived data (2017) may have altered riparian vegetation, affecting departure of current from reference conditions. Since the remote sensing of vegetation continues, it should be possible to assess these effects. Our results support restoration of riparian forests dominated by large trees in the Coast Range and West Cascades. Areas dominated by smaller trees may represent restoration opportunities.
Ecological Characteristics of Diurnal Rest Sites Used by Ringtails (Bassariscus astutus) – Kathleen P. Gundermann, David S. Green, Frances E. Buderman, Cale H. Myers, J. Mark Higley, Richard N. Brown, Sean M. Matthews
The ringtail (Bassariscus astutus) is a species of conservation concern. Yet, little is known about their basic ecology in the northwestern edge of their range, where the habitat differs considerably from their primary range in the southwestern United States. Diurnal rest sites, such as cavities in live and standing-dead trees, are an essential habitat element for ringtails and co-occurring mesocarnivores. Ringtails use diurnal rest sites as shelter during adverse weather conditions, refugia from predators, such as the co-occurring fisher (Pekania pennanti), and dens to raise young. Understanding the forest conditions associated with rest sites selected by ringtails can inform forest management practices. We fixed very high-frequency radio collars to 16 ringtails on the Hoopa Valley Indian Reservation in northern California to better understand the relationships between forest characteristics and fisher presence on ringtail rest site use. We found that ringtails were more likely to select rest sites in mature older forests compared to oak woodland and open areas and were less likely to select rest sites closer to perennial water sources. We did not detect an effect of fishers on the selection of rest sites. These results indicate that both late- and some early-seral forest conditions provide suitable habitat for ringtail rest sites and ultimately demonstrate that ringtails use a mosaic of seral stages in the forests of the Pacific Northwest.
Mound-Building Ants and Associated Termites on Goodale's Cutoff along the Oregon Trail – Brad Kard
Hundreds of ant nest bare mineral soil mounds as well as ant plant litter 'thatch' mounds are distributed across the sagebrush-steppe prairie landscape on Goodale's Cutoff along the Oregon Trail near Arco, Idaho, adjacent to the northern boundary of Craters of the Moon National Monument and Preserve. U.S. Natural Resources Conservation Service personnel and local landowners wanted to determine if these ants were exotic invasive pests that could damage prairie pasture and grazing habitat or impact historic anthropogenic artifacts. Four species of native ants, Pogonomyrmex salinus, Formica limata, F. obscuripes, and F. ravida that are common on the Snake River Plain of Idaho were collected from different mounds. Another native ant, Solenopsis molesta, was foraging around the perimeter of one thatch mound. Additionally, a subterranean termite, Reticulitermes tibialis, common in the western U.S. and widespread within Idaho prairies and mountains was found foraging within both types of ant mounds. This study provides insight into ant and subterranean termite activity on the Snake River Plain.
Postglacial Fire and Vegetation History from Doheney Lake in the Sinlahekin Wildlife Area, Okanogan County, Washington (USA) – Megan K. Walsh, Kevin C. Haydon, Dale Swedberg Pre-print available.
In recent decades, dry Pinus ponderosa-dominated forests of the eastern Cascades have experienced a dramatic increase in large, high-severity wildfires resulting in significant damage to natural resources. However, relatively little is known about long-term trends in postglacial fire activity in these forests. The purpose of this study was to reconstruct the fire and vegetation history of the Doheney Lake watershed, located in north-central Washington, using macroscopic charcoal and pollen analysis of a ca. 12,330 year-long lake sediment record. The results illustrate that regional climatic change, as well as climatically-controlled vegetation shifts, were the primary drivers of fire activity during much of the postglacial period. In particular, the establishment of the modern forest between ca. 7500-6000 cal yr BP due to cooler and moister conditions led to greater amounts of burnable biomass and generally higher levels of fire activity. The study results also suggest that greater interannual climate variability linked to drought may have played a role in the highly variable fire activity during much of the past ~6000 years. Additionally, it is likely that Indigenous cultural burning contributed to the fire activity at the site prior to Euro-American settlement, in particular during the past ~4000 years. Since ca. 125 cal yr BP (1825 CE), an almost complete absence of fire has allowed for the encroachment of shade-tolerant trees and has resulted in the potential for catastrophic wildfire, like that experienced at the site in 2015.
Influences of Succession and Biogeoclimate on Forage Resources for Elk in Northern Idaho – Deborah S. Monzingo, John G. Cook, Rachel C. Cook, Jon S. Horne, Lisa A. Shipley
Natural disturbance shaped forest communities for millennia, but fire suppression and timber harvest declines have altered forest structure across the western U.S., reducing the abundance of forage for ungulates. We evaluated quality and quantity of forage resources for lactating elk (Cervus canadensis) and their calves in relation to season, succession, and biogeoclimate, the latter indexed by potential vegetation (PV) zones, across 36,500 km2 in Idaho’s Clearwater and St. Joe River Basins. In 0.2-ha macroplots (n = 359), we measured characteristics of forest overstory, biomass of current annual growth of undergrowth vegetation (kg/ha), and nutritional content of these plants. Using biomass, digestible energy (kJ/g), digestible protein (DP, g/100 g forage), and prior knowledge of elk diet selection and nutritional constraints, we developed eight forage resource metrics. The greatest abundance of undergrowth vegetation (500–1,000 kg/ha) occurred during the first 20 years after stand-replacing disturbance and declined as the overstory closed in wetter PV zones. Digestible energy decreased whereas DP increased as stands aged. Evidence of nutritional limitations for lactating elk increased markedly after mid-summer—early seral, high elevation spruce-fir forests on productive soils provided the best opportunity for lactating elk to satisfy their requirements in late summer. Our findings demonstrate the importance of disturbance regimes that maintain early seral communities in mosaics with mid- and late seral stages and suggest that implementing stand replacing disturbance in relatively moist forest zones at mid- and high elevations provides the greatest improvement in forage resources for lactating elk and their calves in summer.
Drivers of Forested Riparian Microclimate on the Olympic Peninsula of Washington State – Katrina R. Keleher, Richard E. Bigley, Warren D. Devine
Riparian zones have unique microclimates that support distinct assemblages of aquatic and terrestrial species, which has resulted in a regulatory emphasis in recent decades on riparian protections. However, an understanding of the drivers of riparian microclimate in these protected riparian areas is still lacking. This study examined drivers of variability in summer air temperature and humidity in the riparian zones of ten drainage basins (31-789 ha) on the western Olympic Peninsula, Washington. Model selection analysis was used to explore hypotheses about the influences of three types of drivers on microclimate: regional climate gradients, proximity to stream, and solar radiation. Proximity to stream had the strongest influence on microclimate: the air became warmer and drier with increasing distance from the stream and with increasing steepness of the stream valley slope. Basins at higher elevations (28-362 m) had warmer, drier microclimates, a pattern attributed to greater coastal marine climate influence at lower elevations. Variation in microclimate also was associated with variation in solar exposure modeled as a function of topography. Testing of canopy closure influence on microclimate was hindered by the fact that canopy closure was uniformly high across the study area (87-98%) as a result of unmanaged, primarily second-growth stream buffers. Each of the microclimate drivers identified in this study was a function of topography, across a range of scales. By understanding these relationships between topographic variation and riparian microclimate, managers and researchers will be able to more accurately and efficiently delineate the extent of riparian microclimate influence.
Overwinter Mass Loss of Townsend’s Big-eared Bats in Five Caves – Jericho C. Whiting, Martha C. Wackenhut, Bill Doering
Quantifying overwinter mass loss in bats is important for understanding hibernation energetics, habitat conservation, and the ability of bats to persist with novel pathogens. Townsend’s big-eared bat (Corynorhinus townsendii) is a species of conservation concern. Little is known about overwinter mass loss of this bat in western North America. We conducted a retrospective analysis to quantify overwinter mass loss of 362 females and males during 1987 and 1988 in five caves in an important area for the conservation of this bat in western North America. Although body mass of 13 females in cave C62 averaged 1.1 g heavier than 12 females in cave C54 when captured in October, all those females recaptured in March lost similar percentages of body mass ( = 22.7%) over winter. In cave C27, body mass of six females averaged 2.6 g heavier than eight males when captured in October. Those recaptured females and males in March lost similar percentages of body mass ( = 19.5%) over winter. In caves C27 and C54, mass of 96 male bats decreased by a mean of 21% between October and March. In five caves, mass of 227 female bats decreased by a mean of 23.4% between October and March. Our results indicate that females are heavier than males when entering hibernation, and that females generally lose more mass than males during hibernation. Moreover, female bats entering hibernation in our study area weighed more than female bats of this species in other studies when entering hibernation. Our data provide researchers in western North America with mass loss estimates for female and male Townsend’s big-eared bats.
Influence of Above-Ground Pipeline and Associated Factors on Movement of Winter Active Boreal Mammals in the Alberta In-Situ Oil Sands – Michael L. Charlebois, Hans G. Skatter, Sondre Skatter, John L. Kansas
Above-ground pipelines (AGP) associated with in-situ oil sands may restrict mammal movement potentially increasing extinction probability and decreased reproductive success. Our 12-year study used winter track count techniques to assess the response of winter-active mammals to AGP in northern Alberta, Canada. The primary questions were: Which species were most prone to movement obstruction by AGP, facilities or natural factor(s) and which factor exerted the strongest influence on crossing likelihood. A total of 2,068 trails of 12 different species were observed. All species crossed more than half of the time. Focal species crossed on average eighty percent of the time. Crossing likelihood of white-tailed deer (Odocoileus virginianus), ermine (Mustela erminea), coyote (Canis latrans), lynx (Lynx canadensis), and fisher (Martes pennanti) were significantly influenced by predictors including pipeline height, pipeline corridor width, infrastructure age, vegetation type, and proximity to infrastructure. Deer and lynx crossing likelihood was positively affected by pipe height. Deer, coyote and ermine crossing likelihood was positively affected by age of pipe. Fisher and deer crossing likelihood was negatively affected by pipeline corridor widths. Our investigations show that most species cross AGP with high crossing frequencies of pipe heights ranging from 130 cm to 160 cm. These findings are important for impact mitigation because: the scarcity of published studies of wildlife movement responses to AGP, our inclusion of small and mid-sized carnivores, and, our investigation of multiple factors. We highlight mitigation/design improvements, effects of pipeline corridor widths, and challenges posed by coupling infrastructure with pipelines, serving to reduce movement barriers/fragmentation.
Cascadia Clues to a 1700 Earthquake as Documented in the 1800s – Brian F. Atwater, David K. Yamaguchi, Jessie K. Pearl
Northwest newcomers of the nineteenth century recorded ecological anomalies later ascribed to a Cascadia earthquake. The most salient were subfossil trees in brackish tidelands. James Graham Cooper, as a naturalist attached to the Smithsonian Institution in the 1850s, called attention to western redcedar standing dead in tidal marshes of Shoalwater Bay (modern Willapa Bay). Two such redcedar served as bearing trees for John J. Lowell, then subdividing a Shoalwater Bay township under contract with the General Land Office. Cleveland Rockwell, mapping tidal shores west of Astoria for the United States Coast Survey in 1868, fringed them with radiating symbols that evoke sprawling spruce stumps. Today, redcedar trunks and spruce stumps in these and other tidelands serve as evidence for lowering of coastal land during a Cascadia earthquake in 1700. Since that earthquake, sedimentation and gradual uplift have enabled post-earthquake succession from tidal flat through tidal marsh to new tidal forest. This post-1700 succession had reached an intermediate stage in 1805 at a Columbia River tidal marsh that Meriwether Lewis called a “marsey prairie.” Post-1700 succession in nearby freshwater tidal forests may have influenced Lewis’s division of Sitka spruce into massive upland old growth and smaller tideland trees. These assorted field observations make sense today by analogy with forest death and renewal near Anchorage that the 1964 Alaska earthquake occasioned.
Comparative Phylogeography of Microsnails from the Pacific Northwest – Megan L. Smith, Connor Lang, David Sneddon, Jessica Wallace, Anahí Espíndola, Jack Sullivan, Bryan C. Carstens
Leaf-litter dwelling invertebrates serve an important role in ecosystem function by breaking down nutrients and potentially acting as indicators of habitat quality. However, this community is understudied due to difficulties related to sampling and taxonomic identification. To explore this community, we sampled leaf litter from the Coastal and Cascades ranges of the Pacific Northwest of North America (PNW) and searched > 200 samples for micro-invertebrates. We removed and photographed more than 400 invertebrate specimens, sequenced a portion of the mitochondrial gene cytochrome oxidase I (COI) for 60 samples, and used COI and the BLASTn database to identify invertebrates. Using these sequences and environmental data from the collection localities, we investigated the phylogeographic history of the two best-sampled species of microsnails, Columella edentula (toothless column snail) and Punctum randolphii (conical spot snail). Results suggest that populations of these species from the Coastal and Cascades ranges may have survived in a single refugium during the Pleistocene glacial cycles and recolonized the Coastal and Cascades ranges during the Holocene. Our results add to the knowledge of species responses to the Pleistocene glacial cycles in the PNW and suggest that future studies should aim to increase representation of micro-invertebrates, perhaps using metabarcoding techniques.
Implications of Metrics and Methodology for Juvenile Salmonid Monitoring in Western Oregon Streams – Ronald J. Constable Jr., Erik Suring
We attempted to determine whether electrofishing removal estimates or single pass snorkeling was a more reliable method for Oregon Department of Fish and Wildlife (ODFW) monitoring of juvenile coho salmon (Oncorhynchus kisutch) and steelhead (O. mykiss) abundance and occupancy trends. Based on 1997–2000 data we assumed abundance estimates from the method that tracked more closely with parental abundance would better approximate true juvenile abundance. Parental abundance from spawning ground surveys and juvenile abundance metrics unique to each method were estimated from 2000–2004 and 2007–2008. Parental abundance did not explain the variation in juvenile abundance from either method (r2 < 0.22), invalidating our assumption, but results had relevance for snorkel surveys used in ODFW monitoring. For both species, correlations between density (fish/m²) and abundance (quantity, based on fish/km) estimates from snorkeling were weak (r < 0.379) but correlations between abundance estimates from both methods were strong (r > 0.846); implying abundance was more appropriate than density for ODFW monitoring. Neither method could sample all habitats, and annually variable proportions of coho salmon (15–47%) and steelhead (0–24%) abundance estimates obtained by electrofishing were in pools too shallow to meet the ODFW depth criterion for snorkeling. This resulted in lowering the criterion to ≥ 20 cm in 2010. The lower criterion, relative to original, has not shown differences in trends but 30% more pools have been sampled, resulting in 23% higher abundance estimates with 10% proportionately smaller confidence intervals. These changes improved ODFW monitoring and related management decisions.
Three-year Effects of Crown Removal by Clipping or Burning on Beargrass (Xerophyllum tenax) Size and Biomass – David H. Peter, Timothy B. Harrington
Beargrass (Xerophyllum tenax [Pursh] Nutt.), an evergreen perennial herb of the northern Rocky Mountains, Pacific Northwest and northern California, is used in Native American basketry and commercial floral greens. We studied beargrass size and biomass responses to crown removal by clipping or burning over three years in a coast Douglas-fir (Pseudotsuga menziesii var. menziesii) woodland having variable shrub cover in the southeastern Olympic Peninsula of Washington State. Clipping forested plants resulted in 28% mortality, mostly from smaller plants growing under 26% more total cover than the surviving plants; however, only 3% of completely crown scorched open grown plants died. Three years after treatment, crown width of surviving plants was only 61% of the pre-treatment size for clipped plants compared to 88% for completely crown scorched plants. Regression analyses indicated that the percentage of crown scorch accounted for only 16% and 27% of crown width and foliar height variation, respectively, one year post-burn, decreasing to 10% and 19% at three years post-burn. During the three years after burning, percentage flowering increased linearly to 64% of plants. Three years post-burn foliar browse was higher on crown scorched than on non-crown scorched plants. Although shade tolerant, long-term survival of lowland beargrass is likely limited by combined competition from shrubs and trees. Stand density management is needed to maintain healthy, reproducing populations in the lowlands of western Washington.