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Globally, ungulate–vehicle collisions (UVCs) are a major human safety concern and may also represent a significant source of mortality for some ungulate populations. However, records of UVC based on counts of roadside carcasses or reports by drivers involved in these incidents are assuredly underestimated because not all ungulates struck die immediately or at the roadside or are reported by drivers or authorities. Here, we provide an observation and analysis of the movements of a GPS‐collared bison (Bison bison) that was involved in a UVC on the Alaska Highway and died in a thick boreal forest 29 days later. During that time, she moved 49.7 km from where she was hit. Her daily movement rate (in kilometers per hour) and daily net displacement (in kilometers per day) were significantly greater in the 29‐day period before she was struck compared with 29 days afterward. This vivid example illustrates that individuals injured in a UVC can die several weeks later and at a considerable distance from where they were initially struck. Moreover, when they eventually die, it may be where their carcass would not be found or associated with a UVC. Bison are the largest land mammal in North America and perhaps more robust to some lower impact UVC than smaller bodied species. Even so, if not for the GPS collar on this bison, we would have never known the fate of this individual, and the carcass likely never found. Taken together, the movements and final resting place of this bison illuminate how estimates of mortality as a result of UVC can be underestimated when the animal does not die immediately and in a location where it can be found. Given our data, we further urge managers to consider roadside counts of animals killed in UVC as a minimum estimate when considering options for mitigation. [ABSTRACT FROM AUTHOR]

Groundberries are an important component of the flora of the boreal forest and provide seasonally important food for many birds and mammals, as well as local people in northern Canada. Here, we ask whether there has been a change in the cover of groundberries in the Yukon boreal forest over the last two decades. We monitored five common species at undisturbed forest sites spaced 300 km apart. At our Kluane site, we monitored 710 fixed quadrats per year for 26 years (1997–2022), and at Mayo 500 quadrats per year for 18 years (2005–2022). The cover of four species, Arctostaphylos uva-ursi (L.) Spreng. (bearberry), Arctostaphylos rubra (Rehder & E.H. Wilson) Fernald (red bearberry), Empetrum nigrum L. (crowberry), and Geocaulon lividum (Richardson) Fernald (toadflax), declined annually by 0.2%–0.8% at both sites. In contrast, Vaccinium vitis-idaea L. (lingonberry) increased annually by 0.5% and 0.8%. We tested whether increases in summer temperature and rainfall were correlated with the observed changes but found no significant relationships. These boreal plants are changing in abundance, but we have limited data on the extent and speed of these changes. We recommend experiments to understand the cause(s) of these changes in groundberry productivity. Our study is a start in monitoring important berry species in this critical ecosystem of northern Canada. [ABSTRACT FROM AUTHOR]

While it is well documented that wolves (Canis lupus) hunt and scavenge bison (Bison bison) from some long-established populations, such ecological interactions are not well known for most small, reintroduced populations in the boreal forest. Indeed, predation or scavenging of reintroduced bison in the boreal forest is rarely reported. Yet, documenting instances of bison killed or consumed is imperative to understanding the integration of reintroduced populations into local food webs and ecosystems. Such observations also indicate that reintroduced bison may be under selective pressure from their key predator. We compiled 20 verifiable observations of wolves hunting or scavenging bison from three reintroduced populations in northwestern Canada. We report the first confirmed observations of wolves feeding on bison from the 'Nahanni' and 'Pink Mountain' populations. We also report new records of wolves hunting or scavenging bison from the 'Aishihik' population. Where sex was known, most (14 of 17) bison consumed were females and 17 of 20 were adults (either sex). Contrary to other studies, we found that 7 of 20 bison consumed by wolves were aged individuals. It took 19–50 years since bison were reintroduction before verifiable observations of wolf–bison interactions emerged for these populations, indicating that wolves were likely slow to view reintroduced bison as prey and incorporate them into their diets. These observations are of value mainly because they provide unequivocal evidence that these reintroduced bison populations are becoming integrated into local food webs and beginning to be under selective pressure by their main predator, both of which are hallmarks of ecological restoration. [ABSTRACT FROM AUTHOR]

Many mammals cross large rivers to access seasonal habitats, yet river crossing behavior is poorly acknowledged or understood. Crossing large rivers is inherently risky, with vessel traffic and flooding events increasing the risk of drowning. We investigated river crossing behavior by threatened bison (Bison bison) in the boreal forest, using data from 11 GPS-collared animals to identify when and where they cross a major river. We used kernel densities of GPS locations to identify crossing hotspots, and developed resource selection function (RSF) models that used habitat characteristics to explain crossing behavior based on a priori hypotheses. We then predicted high-probability crossing areas along a 400-km stretch of river using the best-supported RSF model. Bison regularly crossed the river (x̄ = 8.6 crossings/100 days), particularly during summer months. Model selection results suggested that bison may have chosen river crossing areas that maximized access to forage. Bison preferred to cross the river near islands and areas with high seismic line densities, both of which were likely preferred summer foraging habitats. In addition, islands may have been used as temporary stopovers while crossing the river, or for relief from biting insects. Bison crossed the river where the channel was relatively narrow (x̄ = 400 ± 213 m [SD]) and chose days when river discharge was low, likely to reduce the risk of drowning, exhaustion, or hypothermia. While based on a small sample of collared bison, predictions about high-probability crossing areas may be used to inform mitigation measures aimed at reducing bison drowning caused by vessel traffic, which is expected to increase as resource development expands in the region. Our approach may be informative for identifying river crossing hotspots for other mammals that cross major rivers. [ABSTRACT FROM AUTHOR]

Few studies have explicitly examined habitat use by shrews (Sorex spp.) in the boreal forest of western North America. We conducted pitfall trapping in six common xeric habitat types in Yukon, Canada, to determine their relative use by shrews. The overall capture rate was 0.47 shrews per 100 trap nights (TN), with a total sampling effort of 3652 TN. Cinereus shrews (Sorex cinereus; 0.25 per 100 TN) were the most common species, followed by dusky shrews (Sorex monticolus; 0.14 per 100 TN) and American pygmy shrews (Sorex hoyi; 0.08 per 100 TN). Shrew capture rates and species richness was low in all habitat types sampled. Cinereus shrews were captured in similar numbers in boreal mixedwood forest and alpine shrub habitats, and rarely in other lowland forest habitat types. Dusky shrews were captured largely in alpine shrub habitats, while pygmy shrews were captured only in lowland forest habitat types. The relative use of alpine shrub habitat by cinereus shrews and dusky shrews was not expected. Our data was limited by low captures; however, we provide a first approximation of the relative use of common forest types and subalpine shrub habitat in the boreal forest of northwestern Canada. [ABSTRACT FROM AUTHOR]

Understanding habitat use by remnant populations of imperiled species can inform conservation efforts. Arctic ground squirrels (AGS; Urocitellus parryii) occupy alpine and boreal forest habitats in southwestern Yukon, Canada, where populations have been monitored since the 1970s. While alpine populations have remained stable, those in the boreal forest collapsed in the late 1990s and have not recovered. Propelled by the region-wide decline of AGS at low-elevation sites, our purpose was to document site occupancy by remnant populations and to identify habitats that are a high priority for monitoring and have potential for conservation. Using walking transects, we surveyed 155 sites in eight study areas for presence of AGS. Model-averaged occupancy probability was 0.643 (SE = 0.066), and the associated detection probability was 0.835 (SE = 0.075). AGS occurrence was strongly related to increasing habitat openness and also positively influenced by anthropogenic habitat and neighborhood occupancy. The availability of open habitat patches and connectivity among colonies within the boreal forest are consequential for the persistence of low-elevation populations of AGS. These factors may be linked to predator avoidance. Shrubification in the boreal forest as a result of climate warming may reduce AGS ability to detect and avoid predators. Recognizing anthropogenic habitats in land-use planning, and managing potential conflicts with landowners, may be important for the persistence and recovery of AGS at the southern edge of their range. [ABSTRACT FROM AUTHOR]

Mapping habitat selection by threatened species provides critical information for conservation planning. For reintroduced populations, understanding habitat selection is also necessary to predict dispersal and inform selection of new reintroduction sites. Efforts to restore bison Bison bison to the boreal forest hinge on the persistence of geographically isolated populations that occupy diverse landscapes, and for many populations selected habitats are unknown. We used location data from GPS-collared bison to develop seasonal resource selection function (RSF) models and predictive maps for the reintroduced 'Nahanni' population. We accounted for variation in individual behaviour by calculating averaged population-level selection coefficients from individual RSFs, and we compared these results to a pooled RSF from all bison. Individual RSFs revealed variation in habitat selection that was not always captured by the pooled RSF, although there were some consistencies. Bison strongly selected forage-rich graminoid-dominated wetlands (fens) during winter, but less so in summer when there were potential tradeoffs with poor footing and biting flies. In summer, bison selected alternative sources of forage such as herbaceous, shrubby and fluvial habitats (i.e. riverine islands and gravel bars). The observed association with fluvial habitat may be an adaptation to low forage availability on this landscape. Bison also selected roads and anthropogenic clearings associated with resource development, demonstrating potential for human–wildlife conflict. Our predictive maps highlight areas of conservation interest, and should be considered in land use planning and environmental assessments. We demonstrate the value of foraging habitat for forest-dwelling bison, particularly in winter. Identifying forage-rich habitat patches, and connectivity between them, is important when considering sites for new reintroductions or expansion of existing populations. More broadly, our approach may be used to identify areas of high conservation interest, where resources do not allow extensive sample sizes of GPS-collared animals. [ABSTRACT FROM AUTHOR]

The boreal forest is the largest intact forest in the world, and a refuge for species experiencing range retractions as a consequence of climate and landscape change. Yet, large tracts of the boreal forest are threatened by the cumulative impacts of climate change, natural resource extraction, agriculture, and urbanization, perhaps warranting a shift in focus from biodiversity conservation in intact wilderness to that in anthropologically modified landscapes. We investigated landscape features that influence the distribution of the endangered little brown bat (Myotis lucifugus) in an urbanizing boreal landscape at two spatial scales. We hypothesized that little brown bat activity would be influenced by proximity to available building roosts, because roosts are a potential limiting factor for boreal bats. Secondarily, we predicted that bats would use potential foraging habitat, such as waterbodies, and would avoid young, cluttered forests at the landscape scale. We conducted acoustic surveys of bat activity at 210 sites distributed across the study area in Yukon, Canada, within 1‐km grid cells. We tested a priori hypotheses with a set of candidate regression models, accounting for spatial autocorrelation. Our hypothesis about the relative importance of anthropogenic roosts was not supported. Little brown bats were equally active in urban areas (high building density) and rural areas (low building density), perhaps because roosts were adequately available throughout the region. Instead, habitat use was driven by the distribution of potential foraging habitat, particularly waterbodies, which are important sources of aerial insect prey. Little brown bats also avoided young (≤100‐yr‐old) forest at the landscape scale (including areas regenerating after fire), which may have been poor foraging or roosting habitat, and used areas with a smaller agricultural and industrial footprint. Our results suggest that waterbodies and mature forest are important little brown bat habitats that should be protected from urban encroachment. Proactive conservation of important habitat for species at risk is still possible throughout much of the boreal forest, where human densities are comparatively low and the urban footprint is currently small. [ABSTRACT FROM AUTHOR]

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Urban development is detrimental to many wildlife species; however, endangered little brown bats (Myotis lucifugus) may be attracted to human settlements, making them a synurbic species. Buildings likely provide high-quality roosting habitat, which may be a limiting factor in the boreal forest where trees are typically small and potentially unsuitable for hosting large maternity colonies. In the boreal forest, there are relatively few urban developments in a matrix of wilderness and apparently suboptimal natural roosting habitat; thus, we hypothesized that isolated rural villages were islands of summer habitat for little brown bats that may be important for their conservation and recovery. To test this hypothesis, we investigated the relationship between little brown bat activity, foraging rates, and proximity to rural villages. We expected bat activity and foraging rates to increase with proximity to villages, as bats should optimally forage near their roosts to minimize flight costs. We used ultrasonic detectors to passively monitor bat activity near three rural villages in Yukon, Canada, and characterized bat habitat with forest measurements and remotely sensed data. Bat activity increased with proximity to village centers, but foraging activity did not, suggesting that human settlements in the boreal forest were important as roosting rather than foraging habitat. Bat activity was higher near water bodies and areas with relatively high densities of linear features (e.g., roads and transmission lines), perhaps because prey were most abundant near water features and along forest edges. The island phenomenon we observed (i.e., higher bat activity near villages) has also been documented in larger human settlements at lower latitudes, where urban areas provided better roosting habitat than surrounding agricultural matrices. Given that little brown bats were concentrated near rural villages, small human settlements should be a focus of conservation efforts in the boreal forest--particularly the identification and protection of buildings used as maternity colonies. Our study advances knowledge of little brown bat habitat requirements in the boreal forest and identifies habitats that may be important for their recovery. [ABSTRACT FROM AUTHOR]

Fecal pellet counts are often used to assess trends in ungulate population size and habitat use. However, various factors may influence the physical decay and disappearance of pellets, where disappearance may be a result of physical decay and other factors (e.g. trampling, scattering and concealment by vegetation). Knowing pellet decay and disappearance rates in different habitats is a prerequisite to acquiring reliable information from pellet counts. We examined elk Cervus canadensis pellet decay and disappearance of individual pellets and pellet groups in six habitats in the boreal forest of northwestern Canada. We monitored 120 pellet groups deposited in May 2008 at 4, 12, 16 and 28 month intervals (i.e. the end of each of three plant growing seasons) to assess differences in physical decay and disappearance. Pellet decay and disappearance varied among habitats. In moist habitats, pellets showed little sign of decay by the end of our study, likely due to a short plant growing season. In drier, open habitat types, pellet decay was more rapid, likely due to exposure to sun and wind. By the end of our study, the percent of pellets remaining varied from a 14-82% among the sampled habitats. Pellets in moist forest habitats had the lowest decay rates but the highest disappearance rates, whereas those in dry, grassland sites had the highest decay, but the lowest disappearance rates. Our study further demonstrates that ungulate pellet decay and disappearance may differ substantially among habitats, which has important implications for the design of ungulate monitoring programs that utilize pellet counts. We conclude by recommending that fecal accumulation rate (FAR) methods are likely more appropriate in our study area than fecal standing crop (FSC) methods for estimating elk density, because FAR methods are less prone to biases associated with differential pellet decay and disappearance among habitats. [ABSTRACT FROM AUTHOR]

Estimating population densities of small mammals (< 100 g) has typically been carried out by intensive livetrapping, but this technique may be stressful to animals and the effort required is considerable. Here, we used camera traps to detect small mammal presence and assessed if this provided a feasible alternative to livetrapping for density estimation. During 2010-2012, we used camera trapping in conjunction with mark-recapture livetrapping to estimate the density of northern red-backed voles (Myodes rutilus) and deer mice (Peromyscus maniculatus) in the boreal forest of Yukon, Canada. Densities for these 2 species ranged from 0.29 to 9.21 animals/ha and 0 to 5.90 animals/ha, respectively, over the course of this investigation. We determined if hit window--the length of time used to group consecutive videos together as single detections or "hits"--has an effect on the correlation between hit rate and population density. The relationship between hit rate and density was sensitive to hit window duration for Myodes with R² values ranging from 0.45 to 0.59, with a 90-min hit window generating the highest value. This relationship was not sensitive to hit window duration for Peromyscus, with R² values for the tested hit windows ranging from 0.81 to 0.84. Our results indicate that camera trapping may be a robust method for estimating density of small rodents in the boreal forest when the appropriate hit window duration is selected and that camera traps may be a useful tool for the study of small mammals in boreal forest habitat. [ABSTRACT FROM AUTHOR]

• Little brown bat occupancy was unaffected by logging after a bark beetle outbreak. • Habitat use by bats in salvage-logged stands did not vary with tree retention. • Bat occupancy declined in unsalvaged forest stands with basal area >40 m2/ha. • Bats avoided cluttered forests in late summer when juveniles were present. As a consequence of warmer winters, the frequency and severity of bark beetle infestations has increased in western North America, creating controversy over how to manage beetle-killed forests. Post-infestation salvage logging is increasingly used to reduce wildfire risk and recover the value of beetle-killed trees; however, the ecological consequences of this practice are poorly understood. We investigated the effects of post-infestation salvage logging in the boreal forest (Yukon, Canada) on habitat use by the little brown bat (Myotis lucifugus), a forest-dwelling species that is relatively tolerant of vegetative clutter and numerically dominant in boreal bat communities. We hypothesized that little brown bats would select closed-canopied sites, particularly at high latitudes where bats may be vulnerable to predators during midsummer when daylight is nearly continuous. Thus, we expected low occupancy rates in salvage-logged stands, particularly those with low tree retention. Because night length increases drastically after summer solstice, we also predicted that bat preference for closed canopies would decline by late summer. We monitored for bat presence with ultrasound detectors in 30 unlogged, beetle-affected stands and 60 small (<30 ha) salvage-logged stands of variable retention. We used occupancy models to test predictions regarding bat response to logging and associated changes in forest structure at local and landscape scales. Contrary to our predictions, occupancy by little brown bats was generally higher in salvage-logged stands, although differences were not statistically significant. Bat occupancy declined with increasing tree basal area, particularly during the second half of the summer when bats avoided forest stands with basal area >40 m2/ha. Our results suggest that vegetative clutter was a primary constraint for little brown bats. The observed clutter avoidance in late summer may have been caused by the presence of newly volant juveniles, which are not yet proficient at flying in clutter. In addition, bats may have shifted their preference to open habitats during late summer when nights were longer and darker, and perceived predation risk was likely reduced. Our study suggests that small patches of salvage-logged boreal forest may improve foraging habitat for little brown bats through clutter reduction; however, we caution that interpretation of our results should be limited to the tree retention levels and scale of logging at our sites. Additionally, the potential importance of unlogged areas as roosting habitat requires consideration before prescriptions are made on the proportion of the landscape to be salvage-logged. [ABSTRACT FROM AUTHOR]

Accidental mortality of bats is not often observed or reported in the literature. It may, however, have an impact on population size and structure. We report an observation of 53 Little Brown Bats (Myotis lucifugus) being trapped and drowned in a home-made rodent trap at an abandoned cabin in southern Yukon. Traps of this design may be commonly used in the boreal forest. We recommend not using such traps in cabins that are used by colonies of bats. [ABSTRACT FROM AUTHOR]