Search

Motion‐sensitive cameras are commonly used to monitor wildlife occupancy rates; however, few studies have assessed whether data from cameras are correlated with density estimates obtained from more traditional labor‐intensive methods such as those based on capture‐mark‐recapture. We used data from a boreal forest community to test whether camera data were correlated with densities estimated from independent monitoring methods. We placed 72 covert cameras in the forest around Lhù'ààn Mân' (Kluane Lake), Yukon, Canada, for 7 years and tracked changes in population densities by camera hit rates. We independently estimated population densities of snowshoe hares (Lepus americanus) and red squirrels (Tamiasciurus hudsonicus) using capture‐mark‐recapture via live trapping, and Canada lynx (Lynx canadensis), coyotes (Canis latrans), and moose (Alces americanus) by snow track transects. Density estimates obtained from conventional aerial surveys were also periodically available for moose. Except for red squirrels, camera hit rates were highly correlated with population density estimates obtained by traditional methods, including across a large range of estimated densities corresponding to cyclic population dynamics in several species. Accordingly, we infer that motion‐sensitive cameras could supplement or replace traditional methods for monitoring key species in boreal forest food webs. Using cameras to monitor population change has several advantages; they require less effort in the field, are non‐invasive compared to live‐trapping, include multiple species at the same time, and rely less on weather than either aerial surveys or snow track transects. Tracking changes across the vast boreal forest is becoming increasingly necessary because of climate and landscape change and our data validate the use of motion‐sensitive cameras to provide a useful quantitative method for state‐of‐the‐environment reporting. [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]

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]

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]

Copyright of Ecoscience (Ecoscience) is the property of Taylor & Francis Ltd and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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]

After being virtually ignored, bats in northwestern Canada and Alaska have recently been subject to increasing attention by scientists, resource managers, and the public. We review recent advances in bat research in the region and identify key priorities for future research, including what we believe is needed to provide a more coordinated approach to filling in these knowledge gaps. Our knowledge of the diversity and distribution of bats has improved considerably as a result of dedicated survey efforts. Scientists have provided a tantalizing glimpse into the natural history and ecology of bats in far northwestern North America and some of the unexpected adaptations they exhibit in response to the challenges imposed by northern environments. Despite these recent advances, further work is required to document the distribution of bats in the region; identify key summer roosting habitats and hibernacula; assess population status and trends; evaluate the impact of anthropogenic change and develop mitigation strategies; and better understand the natural history ecology of bats in the region. Improving our knowledge of these aspects of bat biology will be useful for informing conservation planning initiatives and environmental impact assessment processes. To ensure that new information is reliable and accessible, we strongly recommend that researchers strive to meet minimum evidentiary standards; deposit data, samples and voucher specimens in appropriate repositories; coordinate monitoring efforts and data collection; and publish or otherwise report results. We hope that our concluding remarks will help guide bat research in northwestern Canada and Alaska, and that the hard-earned results obtained in future studies will impart a positive impact on bat conservation in the region. [ABSTRACT FROM AUTHOR]

Diurnal roost sites are a critical resource for bats. Despite their importance, we know little about the roosting habits of Little Brown Myotis (Myotis lucifugus) in the boreal forest of northwestern Canada and Alaska. To locate diurnal roost sites and determine minimum distances to foraging areas, we radio-tagged 10 Little Brown Myotis (7 adult females, 3 adult males) in the boreal forest of southwestern Yukon, Canada. All of the females roosted in a single building, with 1 using a bat house for 2 nights. In contrast, the males used a variety of roost sites, including buildings, rock cliffs, and trees, and switched roosts periodically. We observed sex-biased movements, with adult males traveling a significantly shorter distance between their diurnal roost sites and a key foraging area than adult females. Males tended to roost near a key foraging area, whereas radio-tagged females flew >5 km from their diurnal roosts to forage. Our data are some of the first obtained via radio-telemetry for Little Brown Myotis in the boreal forest and confirm that the roosting behavior of the sexes is different. That all of the radio-tagged females primarily used 1 roost site in town and flew relatively far to a key foraging area suggests that these critical resources may be somewhat limiting in our study area. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the author discusses various reports within the issue on topics including the advances in bat research in northwestern Canada and Alaska, diversity and distribution of bats in the region and the ecology and life history of bats at northern latitudes.

• 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]

Forage availability, snow depths, and winter temperatures were assessed to determine if they might impose range constraints on introduced elk (Cervus elaphus) that voluntarily colonized a 95 km2 area of southwest Yukon (Canada) in 1959. Parkland-like vegetation of stunted aspen (Populus tremuloides) and nonforest upland plant communities, which is atypical vegetation for a boreal forest environment, composed 30% of the colonized area. About 95% of the area produced less than 300 kg/ha of forage, which represents poor productivity compared to more southern elk ranges. In the remaining 5%, indigenous graminoid communities produced (average ± SD) 408 ± 131 kg/ha of forage, exceeded only by nonindigenous roadside vegetation with 652 ± 115 kg/ha. Data from radio-collared animals indicated that most elk occurrences (38% year-round) were associated with parkland-like vegetation, and fecal pellet groups were six times as frequent in indigenous graminoid vegetation as in forest vegetation. Late February 2011 snow depths of 41 ± 7 cm, during a year with a below-normal snowfall, suggested a potential for reduced winter access to forage. Meteorological data from 1981 - 2010 indicate that one-third of winter daily minima in the study area were likely lower than -20°C, a threshold below which the metabolism of an elk calf must increase to maintain its body temperature. Each assessed habitat variable was unfavorable to elk compared with other western North American winter ranges, which may have limited the development of a more robust population in the southwestern Yukon. [ABSTRACT FROM AUTHOR]