Western Montana Research Articles

Roost characteristics and fidelity of silver‐haired bat maternity colonies in a floodplain cottonwood forest

AbstractThe maternal roosting behavior of migratory, tree‐dwelling bat species remains poorly understood. From 2016 to 2020 we radio‐tagged 53 adult female silver‐haired bats (Lasionycteris noctivagans) and tracked them to their day roosts to evaluate roosting habits in a cottonwood (Populus) forest in the floodplain of the Bitterroot River in western Montana. We investigated roost tree characteristics of maternity colonies such as canopy closure, tree size, and decay stage, as well as the daily roost fidelity of tagged bats. Additionally, we marked 55 bats with passive integrated transponder (PIT) tags to assess interannual fidelity to summer habitat. We tracked bats to 94 unique roost trees. Based on previous studies, we expected silver‐haired bat maternity colonies to roost in tall, large diameter trees. We modeled roosting probability as a function of tree height, day of year, and the interaction of these terms. We found bats preferred taller trees earlier in the year, but overall roosting probability decreased throughout the season and tree height had lesser influence on roosting probability later in the year. Bats used tall trees with high canopy closure in early stages of decay during periods of pregnancy and lactation, while the effect of these tree attributes lessened later in the season, perhaps after lactation when energetic constraints were reduced for adult females to prepare for migration by entering torpor during the day. Bats used an average of 5.2 roost trees during the young rearing period and remained in the same roost for an average of 1.5 consecutive days. While daily roost fidelity was low, we documented interannual fidelity to summer habitat from nine individuals. We found silver‐haired bat roosting preferences vary with time, are tree‐specific, and policies targeting conservation of the species should manage flood regimes to promote cottonwood establishment, height growth, and a mosaic of riparian habitats.

Behavioral Responses to Wildfire Smoke: A Case Study in Western Montana.

Although climate change is increasing wildfire and smoke events globally, public health messaging and individual access to resources for protection are limited. Individual interventions can be highly effective at reducing wildfire smoke exposure. However, studies related to individual responses to wildfire smoke are limited and demonstrate mixed protective behaviors and risk perception. Our research helps fill this gap by assessing the self-reported behavior of 20 participants during wildfire season in Western Montana from 28 June through 1 November, 2022. We also measured continuous outdoor and indoor fine particulate matter (PM2.5) concentrations at participant residencies during this time period using PurpleAir sensors (PAII-SD, PurpleAir, Inc, USA) while participants took up to 16 self-reported online weekly activity surveys. Mixed-effect Poisson regression models were used to assess associations between exposure variables and participant reported behaviors. These results were compared with end-of-study interview findings. Wildfire smoke impacted days and increased concentrations of PM2.5 were associated with decreased outdoor exercise and opening of windows for ventilation. Interview themes were congruent with the regression analysis, with the additional finding of high portable air cleaner (PAC) use among participants. Additionally, these interviews gave context to both the tradeoffs participants face when making protective decisions and the importance of personal air quality data in increasing awareness about wildfire smoke risks. Future wildfire smoke studies can build off this research by providing personally relevant air quality data and PACs to participants and by improving public health messaging to address the compounding risks of wildfire smoke exposure and heat.

Comparing camera‐based ungulate density estimates: a case study using island populations of bighorn sheep and mule deer

AbstractCamera‐based abundance estimators are an alternative methodology of growing interest in both research and management applications. The statistical formulations of camera‐based abundance estimators using time‐lapse data should theoretically produce precise and unbiased estimates; however, production of unbiased results also requires meeting several important assumptions, and real‐world case studies evaluating such results remain relatively few. We applied instantaneous sampling (IS) and space‐to‐event (STE) estimators to remote camera data collected in April 2021 via time‐lapse sampling of closed populations of bighorn sheep (Ovis canadensis) and mule deer (Odocoileus hemionus) on Wild Horse Island in western Montana, USA, and compared results for bighorn sheep to aerial and ground‐based counts. Point estimates from camera‐based approaches underestimated bighorn sheep populations by 32–44% (IS estimator) and 62–69% (STE estimator) relative to aerial and ground counts. Patchy spatial distribution and group‐living behavior of sheep resulted in a high degree of noise surrounding the IS estimate. In comparison, a low point estimate with relatively narrow confidence intervals suggested potential sensitivity of the STE estimator to violating assumptions of independence among individual animals and sampling occasions. Estimates of mule deer had improved precision over sheep estimates, as indicated by lower estimated coefficients of variation of the mean (CVmean) derived from the analytic SE estimator. Using 15‐m viewsheds and the IS estimators, mule deer density estimates came with a 26% CVmean compared to 43% CVmean for bighorn sheep. This discrepancy may be a result of differences in distribution, behavior, and relative abundance between the 2 species. Accounting for group size and increasing time between sampling may improve accuracy of density estimates and adhere better to model assumptions when estimating precision. In addition, factors influencing viewshed and resulting density extrapolations must be considered carefully. While camera‐based methods theoretically provide an alternative way to estimate density when traditional methods are impractical, our results suggest that more work is needed to ensure density estimates are accurate and precise enough to inform population management.

Impact and recovery of forest cover following wildfire in the Northern Rocky Mountains of the United States

BackgroundAnthropogenic climate change is expected to catalyze forest conversion to grass and shrublands due to more extreme fire behavior and hotter and drier post-fire conditions. However, field surveys in the Northern Rocky Mountains of the United States show robust conifer regeneration on burned sites. This study utilizes a machine learning (GBM) approach to monitor canopy cover systematically on a census of burned areas in two large wilderness areas from 1985 to 2021, to contextualize these recent field surveys and create a monitoring baseline for future change.ResultsA predictive model was developed from coincident LiDAR and Landsat observations and used to create time series of canopy cover on 352 burned sites (individual wildfires subset by number of times burned), which were then summarized using fire impact and recovery metrics. Fire impact, defined as canopy cover loss relative to pre-fire condition, was highly correlated with burn severity (Spearman’s R = 0.70). Recovery was characterized by the following: (1) whether a burned area began gaining canopy cover and (2) how long would it take to reach pre-fire cover given observed rates of gain. Eighty-five percent of the land area studied showed evidence of recovery. Areas that are failing to recover are burning more recently than their recovering counterparts, with 60% of non-recovering sites burning for the first time after 2003. However, the 5-year probability of recovery is similar among recent burns and for those that burned earlier in the record, suggesting that they may recover with more time. Once sites begin recovering, median time to reach pre-fire cover is 40 years. Seven sites have expected recovery times greater than 200 years, six of which burned for the first time after 2006.ConclusionOverall, burned sites in wilderness areas of the Northern Rocky Mountains are broadly recovering from wildfire. However, anthropogenic climate change adds a layer of uncertainty to the future prognosis of conifer recovery. This work provides a framework for systematic monitoring into the future and establishes a baseline of impact and recovery in the mountains of western Montana and northern Idaho.

Many Benefits Realized After a Long‐Term Fuel Reduction and Restoration Study in Western Montana

Many Benefits Realized After a Long‐Term Fuel Reduction and Restoration Study in Western Montana

Seasonal extreme temperatures and short-term fine particulate matter increases pediatric respiratory healthcare encounters in a sparsely populated region of the intermountain western United States

BackgroundWestern Montana, USA, experiences complex air pollution patterns with predominant exposure sources from summer wildfire smoke and winter wood smoke. In addition, climate change related temperatures events are becoming more extreme and expected to contribute to increases in hospital admissions for a range of health outcomes. Evaluating while accounting for these exposures (air pollution and temperature) that often occur simultaneously and may act synergistically on health is becoming more important.MethodsWe explored short-term exposure to air pollution on children’s respiratory health outcomes and how extreme temperature or seasonal period modify the risk of air pollution-associated healthcare events. The main outcome measure included individual-based address located respiratory-related healthcare visits for three categories: asthma, lower respiratory tract infections (LRTI), and upper respiratory tract infections (URTI) across western Montana for ages 0–17 from 2017–2020. We used a time-stratified, case-crossover analysis with distributed lag models to identify sensitive exposure windows of fine particulate matter (PM2.5) lagged from 0 (same-day) to 14 prior-days modified by temperature or season.ResultsFor asthma, increases of 1 µg/m3 in PM2.5 exposure 7–13 days prior a healthcare visit date was associated with increased odds that were magnified during median to colder temperatures and winter periods. For LRTIs, 1 µg/m3 increases during 12 days of cumulative PM2.5 with peak exposure periods between 6–12 days before healthcare visit date was associated with elevated LRTI events, also heightened in median to colder temperatures but no seasonal effect was observed. For URTIs, 1 unit increases during 13 days of cumulative PM2.5 with peak exposure periods between 4–10 days prior event date was associated with greater risk for URTIs visits that were intensified during median to hotter temperatures and spring to summer periods.ConclusionsDelayed, short-term exposure increases of PM2.5 were associated with elevated odds of all three pediatric respiratory healthcare visit categories in a sparsely population area of the inter-Rocky Mountains, USA. PM2.5 in colder temperatures tended to increase instances of asthma and LRTIs, while PM2.5 during hotter periods increased URTIs.

Private land conservation towards large landscape goals: Role of relational values, property rights orientations and perceived efficacy in ranchers' actions

Abstract Many of the world's iconic, endangered and endemic species rely on large, contiguous landscapes for their survival. In the US West, working ranches are integral to large landscape conservation goals and there are numerous influences on ranchers' conservation actions, including their relational values, perceived self‐efficacy and property rights concerns. Using survey data from 681 ranchers in eastern Idaho and western Montana, we sought to answer the question: How do relational values, property rights orientations, perceived efficacy and public lands dependence affect reported conservation actions on private ranch lands? Conservation adoption varied widely by action, with invasive plant removal having the highest (92%) and conifer removal the lowest (21%) rates of adoption. Conservation adoption was higher among ranchers who believe they are responsible for conserving nature, believe their land should be used to provide environmental benefits to the region, have higher perceived self‐efficacy, lower property rights concerns and higher incomes. Programmes encouraging the adoption of conservation on private lands could benefit from message framing that resonates with the worldviews of landowners and land managers. Read the free Plain Language Summary for this article on the Journal blog.

Western Montana Snow Squall Climatology and Synoptic Patterns, 2000–2020

The rapid onset of whiteout conditions, from strong winds, blowing snow, and heavy snow, associated with snow squalls often results in hazardous travel conditions. Snow squalls bring pronounced impacts to the transportation sector, leading to accidents, fatalities, and significant travel delays. Given these impacts, historical frequencies, and the synoptic environments associated with snow squalls in western Montana were examined to develop forecast aides, primarily through synoptic pattern recognition, for meteorologists to identify and communicate snow squalls. A 20-yr climatology was constructed to identify events characterized by wind gusts ≥26 kt (30 mph) and visibility ≤0.8 km (0.5 mi). 74 snow squall events were identified from 2000 through 2020 across three ASOS sites: Missoula (KMSO), Kalispell (KGPI), and Butte (KBTM). The median duration of heavy (moderate) snow during snow squalls was 26 (34) min. A composite study utilizing these events was conducted using the NCEP North American Regional Reanalysis. The composite study along with surface observations, revealed three distinct snow squall patterns and types: orographic snow bands, Pacific cold fronts, and Canadian arctic fronts.

Stratigraphic and geochronologic investigation of the Muddy Creek Basin: Implications for the Eocene tectonic evolution of southwest Montana, USA

Sedimentary basins record crustal-scale tectonic processes related to the construction and demise of orogenic belts, making them an invaluable archive for the reconstruction of the evolution of the North American Cordillera. In southwest Montana, USA, the Renova Formation, considered to locally represent the earliest accumulation following Mesozoic−Cenozoic compressional deformation, is widespread but remains poorly dated, and its origin is debated. Herein, we employed detrital zircon U-Pb and (U-Th)/He double dating and sanidine 40Ar/39Ar geochronology in the context of decimeter-scale measured stratigraphic sections in the Renova Formation of the Muddy Creek Basin to determine basin evolution and sediment provenance and place the basin-scale record within a regional context to illuminate the lithospheric processes driving extension and subsidence. The Muddy Creek Basin is an extensional half graben in southwest Montana that is ∼22 km long and ∼7 km wide, with a >800-m-thick sedimentary package. Basin deposition began ca. 49 Ma, as marked by multiple ignimbrites sourced from the Challis volcanic field, which are overlain by a tuffaceous fluvial section. Fluvial strata are capped by a 46.8 Ma Challis ignimbrite constrained by sanidine 40Ar/39Ar dating. An overlying fossiliferous limestone records the first instance of basinal ponding, which was coeval with the cessation of delivery of Challis volcanics−derived sediment into the Green River Basin. We attribute initial ponding to regional drainage reorganization and damning of the paleo−Idaho River due to uplift and doming of the southern Absaroka volcanic province, resulting in its diversion away from the Green River Basin and backfilling of the Lemhi Pass paleovalley. Detrital zircon maximum depositional ages and sanidine 40Ar/39Ar ages show alternating fluvial sandstone and lacustrine mudstone deposition from 46 Ma to 40 Ma in the Muddy Creek Basin. Sediment provenance was dominated by regionally sourced, Challis volcanics−aged and Idaho Batholith−aged grains, while detrital zircon (U-Th)/He (ZHe) data are dominated by Eocene cooling ages. Basin deposition became fully lacustrine by ca. 40 Ma, based on an increasing frequency of organic-rich mudstone with rare interbedded sandstone. Coarse-grained lithofacies became prominent again starting ca. 37 Ma, coeval with a major shift in sediment provenance due to extension and local footwall unroofing. Detrital zircon U-Pb and corresponding ZHe ages from the upper part of the section are predominantly Paleozoic in age, sourced from the Paleozoic sedimentary strata exposed in the eastern footwall of the Muddy Creek detachment fault. Paleocurrents shift from south- to west-directed trends, supporting the shift to local sources, consistent with initiation of the Muddy Creek detachment fault. Detrital zircon maximum depositional ages from the youngest strata in the basin suggest deposition continuing until at least 36 Ma. These data show that extension in the Muddy Creek Basin, which we attribute to continued lithospheric thermal weakening, initiated ∼10 m.y. later than in the Anaconda and Bitterroot metamorphic core complexes. This points to potentially different drivers of extension in western Montana and fits previously proposed models of a regional southward sweep of extension related to Farallon slab removal.

Amphibitic stoneflies (Plecoptera) are integrators of ecosystem processes in alluvial aquifers of gravel‐bed river floodplains

AbstractOver 50 years ago nymphs of the Plecoptera species, Paraperla frontalis Banks, 1906 (Plecoptera: Chloroperlidae), were shown to exist in a shallow floodplain aquifer of the Tobacco River, a gravel‐bed river in western Montana and later they were documented throughout the main stems of the Flathead River system. Nymphs are almost never found in surface waters, until they emerge on the river shorelines. As teneral adults, they mate and subsequently deposit fertilized eggs into the river. This novel life cycle is termed “amphibitic.” Over the years we and others have found P. wilsoni Ricker, 1965 (Plecoptera: Chloroperlidae), Kathroperla perdita Banks, 1920 (Plecoptera: Kathroperlidae), and five species of Isocapnia Banks, 1938 (Plecoptera: Capniidae), including long‐winged and brachypterous adults and wingless dwarfs (male and female), occupying amphibitic niches in the alluvial aquifers of rivers in Washington, Idaho, Colorado, Alaska and British Columbia. These stoneflies are remarkably tolerant of hypoxia which allows them to exist as abundant consumers in aquifer food webs subsidized by ancient methane. Indeed, stonefly tissues contain carbon that is up to 7000 years old, underscoring the existence of a strong interaction involving the uptake of labile carbon derived from methanogenic and methanotrophic process in aquifers. Details of life cycles, trophic relationships, distribution and abundance have been documented by a suite of studies on the Nyack Floodplain of the Middle Flathead River, Montana. In this paper we review the ecophysiology and ecology of these unique stoneflies in the context of their functional role in gravel‐bed river ecosystems.This article is categorized under: Water and Life > Nature of Freshwater Ecosystems Water and Life > Conservation, Management, and Awareness

SEEDING RESILIENCE: THE IMPACTS OF A SEED-SAVING NETWORK IN WESTERN MONTANA

ABSTRACT The practice of saving seed is as old as agriculture, although due to an increasingly industrialized, economically concentrated, and globalized agricultural system, it has dwindled worldwide. Understanding how community-based, seed-saving networks continue to thrive, and their potential impacts, may shed light on the creation of more resilient agro-ecosystems. This inquiry assessed a seed-saving network and its impacts in the Bitterroot and Missoula valleys of western Montana. The guiding question for this inquiry was: How does a local seed-saving network contribute to the social-ecological resilience of the local agro-ecosystem? The main methods of data collection were semistructured interviews and participant observation. We addressed our research question first by defining our network as a “rooted network,” and then by exploring “resilience effects,” or resultant resilience that emerged from actor connections. In conclusion, we reflect how this informal seed-saving network might play vital roles in fostering resilience of local agro-ecosystems now and in the future. Keywords: agro-ecosystem, rooted network, informal seed network, seed-saving, social-ecological system, resilience, Montana.

Stereocaulon tomentosoides, a new combination for a western North American endemic species with cyanobiont and chemotype polymorphisms

Based on resampling the type locality and surrounding regions, along with phylogenetic analysis of molecular data, we elevate Stereocaulon sasakii var. tomentosoides to the species level, while we treat S. sasakii var. simplex as an environmental modification of S. tomentosoides. We found no phylogenetic evidence that any variety of S. sasakii occurs in North America, so we suggest that the species be removed from the North American list and its North American varieties transferred to S. tomentosoides. Stereocaulon tomentosoides is so far confirmed only from the Pacific Northwest of North America. Furthermore, it is largely allopatric with S. tomentosum, apart from a small region of overlap in northern Idaho and western Montana. While S. tomentosum always contains stictic acid and never lobaric acid as secondary metabolites, S. tomentosoides differs in having a predominant chemotype of lobaric acid as the major substance, with an infrequent chemotype containing both lobaric and stictic acids. While S. tomentosoides usually contains Nostoc in the cephalodia, occasional individuals, especially from old mossy lava flows, contain Stigonema; one specimen was found with both kinds of cephalodia on a single thallus. Phylogenetic analysis of these species and other close relatives revealed an additional species described here, S. cyaneum, so far known only from the Great Lakes region of the United States and Canada and separated from S. tomentosum by its bluish coloration, wet or dry

Long-term video and genetic data yield insights into complex sociality of a solitary large carnivore

American black bears (Ursus americanus) may be more social than currently understood. We used long-term video and genetic data to evaluate social interactions among wild, independent-aged black bear on a conservation property in western Montana, USA. We used multinomial logistic regression to evaluate predictions about male-male interactions within the context of individual fitness, female-female interactions within the context of inclusive fitness, and male-female interactions within the context of female counterstrategies to infanticide. Overall, our findings challenged the assumption that independent-aged bears interact only during the mating season or when concentrated feeding sites are present. We documented 169 interaction events by at least 66 bear pairs, 92 (54%) of which occurred outside of the peak mating season and in the absence of concentrated feeding sites. The probability that male-male pairs engaged in play and other non-agonistic behaviours was higher than that for female-female pairs. Conversely, the probability that female-female pairs engaged in chase behaviour was higher than that for male-male and male-female pairs. We documented evidence of female mate choice, female resource defense, sexually selected infanticide (SSI), and female counterstrategies to avoid SSI. Our findings improve our understanding of ursid ethology and underscore the complexity of ursid sociality.

Autumn resource selection by female elk in a recently burned landscape in western Montana

AbstractWildfire activity across the western United States has increased in recent decades, with wildfires burning at a higher severity and larger scale. The effect of wildfires on forest structure and wildlife habitat is largely influenced by wildfire severity; however, few studies have evaluated the effects of wildfire severity on resource selection of ungulates, particularly during hunting seasons, when knowledge of resource selection is essential for making informed management decisions. To fill this knowledge gap, we fit resource selection probability functions for female elk (Cervus canadensis) in years 2 and 3 post‐wildfire to evaluate the effects of wildfire severity and other environmental and anthropogenic factors on elk resource selection during 4 autumn periods with varying levels of hunter pressure (prehunt, archery‐only, backcountry rifle, and rifle). The probability of female elk selecting low‐severity burned forests during the prehunt, archery‐only, backcountry rifle, and rifle periods was 0.99 (95% credible interval [CrI] = 0.98–1.00), 0.99 (CrI = 0.97–1.00), 0.99 (CrI = 0.99–1.00), and 0.0010 (CrI = 0.00067–0.0015]), respectively, and did not strongly differ from the probability of selecting high‐severity burned forests. During the prehunt period, elk also selected areas with greater forage quality and areas farther from open roads. Elk selected similar resources during the archery period, and selected areas with higher hunter pressure. Elk started leaving hunting districts that had higher snowpack (i.e., snow water equivalent; β = −0.84, CrI = −0.96–−0.72) and allowed rifle hunting (β = −5.39, CrI = −5.80–−4.97) but still selected areas with higher hunter pressure (β = 0.92, CrI = 0.78–1.07) during the backcountry rifle period. During the rifle period, elk continued avoiding areas with high snowpack (β = −3.96, CrI = −4.22–−3.71) and started selecting areas with lower hunter pressure (β = −1.71, CrI = −1.79–−1.64) and lower canopy cover. Overall, wildfire affected elk distributions in early autumn 2 and 3 years after fire in our study area, with limited differences in resource selection between wildfire severity categories. By late autumn, hunter pressure and snowpack were the primary factors influencing elk distribution, and wildfire had little influence on selection. When estimating wildfire effects on elk movements during autumn and establishing appropriate hunting regulations, managers should consider the hunting season, hunter pressure, timing and amount of snowpack, location of traditional winter range, and the seasonal elk range burned, as all these factors may contribute to how elk use the landscape in autumn.

Identification of Spatial Clusters of Undervaccination Patterns Among Children Aged

Spatial clustering of undervaccination leads to increased risk of vaccine-preventable diseases. We identified spatial clustering of undervaccination patterns among children aged <24 months in Montana. We used Montana's immunization information system data to analyze deidentified vaccination records of children aged <24 months born from January 2015 through November 2017. We measured 3 outcomes that were not mutually exclusive: not completing the combined 7-vaccine series by age 24 months, having an undervaccination pattern indicative of parental hesitancy, and having an undervaccination pattern indicative of structural barriers to timely vaccination. Using geomasked residential addresses, we conducted separate Bernoulli spatial scans with a randomization P < .01 to identify spatial clusters consisting of ≥100 children for each outcome and calculated the relative risk of having the undervaccination pattern inside versus outside the cluster. Of 31 201 children aged <24 months included in our study, 11 712 (37.5%) had not completed the combined 7-vaccine series by age 24 months, and we identified 5 spatial clusters of this outcome across Montana. We identified 4 clusters of undervaccination patterns indicative of parental vaccine hesitancy, all in western Montana. The cluster with the largest relative risk (2.3) had a radius of 23.7 kilometers (n = 762 children, P < .001). We also identified 4 clusters of undervaccination patterns indicative of structural barriers, with 3 of the largest clusters in eastern Montana. In Montana, different strategies to increase routine and timely childhood vaccination are needed in distinct areas of this large and predominantly rural state. Immunization information system data can pinpoint areas where interventions to increase vaccination uptake are needed.

Heavy metal concentrations in Canada geese, snow geese, mallards, and American coots from the northern Rocky Mountains in Montana

AbstractThe presence of metals in migratory bird tissues is well established and mining as an anthropogenic source of exposure to metals is well reported in the scientific literature. Determining the difference between what are hypothesized as normal metal levels and those associated with acute mining toxicity is challenging as spatial and temporal overlap of migratory birds with anthropogenic point sources can be highly variable at individual, population, and species levels. We examined the concentrations of 5 geologically prominent metals and metalloids in the region (arsenic, cadmium, copper, manganese, and zinc) in tissues (kidney, n = 64; liver, n = 65; and muscle, n = 65) from 4 species common to the northern Rocky Mountains in western Montana (Canada goose, Branta canadensis, n = 12; snow goose, Anser caerulescens, n = 15; mallard, Anas platyrhynchos, n = 32; and American coot, Fulica americana, n = 6), to identify metal concentrations for comparison to acute mining‐associated mortalities. Metal levels were highly variable across tissue types for all species. For example, the highest concentrations of copper, manganese, and zinc were measured in the liver (18,300, 3,960, and 38,200, respectively; ug/kg), while cadmium levels were highest in the kidney (973 ug/kg). Among species and tissue types, metal levels were also highly variable. For example, copper levels in mallards were highest in the kidney (6,700 ug/kg) and lowest in muscle (2,780 ug/kg). In contrast, copper levels in American coots were highest in muscle (14,400 ug/kg) and lowest in the kidney (5,060 ug/kg). While the wide variation in metal concentrations among species and tissue types measured in our study can make for difficult comparisons, the results are similar to control cases from other peer‐reviewed publications, and several times lower than dose‐response experiments and incidents in which mining‐associated mortality was known. Our results provide metal concentrations in migratory bird species that utilize the northern Rocky Mountains through Montana, which are essential data for assessing exposure, risk, and mortality associated with anthropogenic activities in the region.

Predicted connectivity pathways between grizzly bear ecosystems in Western Montana

Habitat and corridor mapping are key components of many conservation programs. Grizzly bear populations in the continental US are fragmented and connectivity among federal recovery areas is a conservation goal. Building on recent work, we modeled movements to predict areas of connectivity, using integrated step selection functions (iSSFs) developed from GPS-collared grizzly bears (F = 46, M = 19) in the Northern Continental Divide Ecosystem (NCDE). We applied iSSFs in a >300,000 km2 area including the NCDE, Cabinet–Yaak (CYE), Bitterroot (BE), and Greater Yellowstone (GYE) Ecosystems. First, we simulated directed movements (randomized shortest paths with 3 levels of exploration) between start and end nodes across populations. Second, we simulated undirected movements from start nodes in the NCDE, CYE, or GYE (no predetermined end nodes). We summarized and binned results as classes 1 (lowest relative predicted use) – 10 (highest relative predicted use) and evaluated predictions using 127 outlier grizzly bear locations. Connectivity pathways were primarily associated with mountainous areas and secondarily with river and stream courses in open valleys. Values at outlier locations indicated good model fit and mean classes at outlier locations (≥7.4) and Spearman rank correlations (≥0.87) were highest for undirected simulations and directed simulations with the highest level of exploration. Our resulting predictive maps can facilitate on-the-ground application of this research for prioritizing habitat conservation, human-bear conflict mitigation, and transportation planning. Additionally, our overall modeling approach has utility for myriad species and conservation applications.

Fine particulate matter infiltration at Western Montana residences during wildfire season

Background/aimsWildfire air pollution is a growing public health concern as wildfires increase in size, intensity, and duration in the United States. The public is often encouraged to stay indoors during wildfire smoke events to reduce exposure. However, there is limited information on how much wildfire smoke infiltrates indoors at residences and what household/behavioral characteristics contribute to higher infiltration. We assessed fine particulate matter (PM2.5) infiltration into Western Montana residences during wildfire season. MethodsWe measured continuous outdoor and indoor PM2.5 concentrations from July–October 2022 at 20 residences in Western Montana during wildfire season using low-cost PM2.5 sensors. We used paired outdoor/indoor PM2.5 data from each household to calculate infiltration efficiency (Finf; range 0–1; higher values indicate more outdoor PM2.5 infiltration to the indoor environment) using previously validated methods. Analyses were conducted for all households combined and for various household subgroups. ResultsMedian (25th percentile, 75th percentile) daily outdoor PM2.5 at the households was 3.7 μg/m3 (2.1, 7.1) during the entire study period and 29.0 μg/m3 (19.0, 49.4) during a 2-week period in September impacted by wildfire smoke. Median daily indoor PM2.5 at the households was 2.5 μg/m3 (1.3, 5.5) overall and 10.4 μg/m3 (5.6, 21.0) during the wildfire period. Overall Finf was 0.34 (95 % Confidence Interval [95%CI]: 0.33, 0.35) with lower values during the wildfire period (0.32; 95%CI: 0.28, 0.36) versus non-wildfire period (0.39; 95%CI: 0.37, 0.42). Indoor PM2.5 concentrations and Finf varied substantially across household subgroups such as household income, age of the home, presence of air conditioning units, and use of portable air cleaners. ConclusionsIndoor PM2.5 was substantially higher during wildfire-impacted periods versus the rest of the study. Indoor PM2.5 and Finf were highly variable across households. Our results highlight potentially modifiable behaviors and characteristics that can be used in targeted intervention strategies.

1D Seismic Velocity Models for West-Central and Western Montana

Abstract In seismically active areas with infrequent large-magnitude earthquakes, high-quality seismic data are critical for determining accurate seismic velocity models. Here, we present a new local-scale crustal seismic velocity model in west-central Montana as well as a new regional-scale crustal and upper mantle seismic velocity model for broader western Montana. These models are constrained by phase arrivals from several seismic networks, including the University of Montana Seismic Network, the Montana Regional Seismic Network, the Advanced National Seismic System, temporary deployments by the U.S. Geological Survey, and the USArray Transportable Array. We jointly invert for hypocenters and velocity structure using the VELEST software. The local seismic velocity model is the first model specific to west-central Montana, using P-wave arrivals from aftershocks of the 2017 M 5.8 Lincoln, Montana, earthquake. The local model consists of eight layers down to 30 km depth below the mean sea level and spans a region of approximately 40,​000 km2 (200 km × 200 km). The velocity of the uppermost layer in the local model is 4.80 ± 0.11 km/s, and the velocity of the lowermost layer resolved from the data is 7.00 ± 0.05 km/s. Using an expanded dataset across a broader geographical area, we develop a “regional” seismic velocity model that represents spatially averaged velocity structure across western Montana. The regional model consists of thirteen layers down to 45 km depth below the sea level and is appropriate to an area of 160,​000 km2 (400 km × 400 km). The velocity of the uppermost layer is 4.30 ± 0.15 km/s, and the velocity of the lowermost layer is 8.00 ± 0.04 km/s. The new models are similar to prior velocity models for western Montana, but feature improved vertical resolution of layer velocities.

UAV-Based Hyperspectral Imaging for River Algae Pigment Estimation

Harmful and nuisance algal blooms are becoming a greater concern to public health, riverine ecosystems, and recreational uses of inland waterways. Algal bloom proliferation has increased in the Upper Clark Fork River due to a combination of warming water temperatures, naturally high phosphorus levels, and an influx of nitrogen from various sources. To improve understanding of bloom dynamics and how they affect water quality, often measured as algal biomass measured through pigment standing crops, a UAV-based hyperspectral imaging system was deployed to monitor several locations along the Upper Clark Fork River in western Montana. Image data were collected across the spectral range of 400–1000 nm with 2.1 nm spectral resolution during two field sampling campaigns in 2021. Included are methods to estimate chl a and phycocyanin standing crops using regression analysis of salient wavelength bands, before and after separating the pigments according to their growth form. Estimates of chl a and phycocyanin standing crops generated through a linear regression analysis are compared to in situ data, resulting in a maximum R2 of 0.96 for estimating fila/epip chl-a and 0.94 when estimating epiphytic phycocyanin. Estimates of pigment standing crops from total abundance, epiphytic, and the sum of filamentous and epiphytic sources are also included, resulting in a promising method for remotely estimating algal standing crops. This method addresses the shortcomings of current monitoring techniques, which are limited in spatial and temporal scale, by proposing a method for rapid collection of high-spatial-resolution pigment abundance estimates.