The bat fauna of Alaska and northwestern Canada remains poorly known, principally due to a lack of dedicated surveys. To better assess the diversity of bats in the region, we conducted full-spectrum acoustic surveys at several sites in Yukon, Canada. During our surveys we obtained the 1st acoustic records of Hoary Bat (Lasiurus cinereus) and Long-Legged Myotis (Myotis volans) in Yukon. Neither species had been documented previously in the territory, but one or both species were known from adjacent Alaska, British Columbia, and Northwest Territories. Characteristics of certain echolocation calls of Hoary Bats and Long-legged Myotis are difficult to confuse with other species that might also occur in the region. In addition, we made other noteworthy recordings; however, species identification for these other echolocation calls was ambiguous. These 1st records significantly increase our knowledge of the ranges of these bat species in Yukon, Canada. Further acoustic surveys, coupled with live captures, will help us further understand the diversity and distribution of bats in Yukon.

Few bat inventories have taken place in Northwest Territories (NWT), Canada, an area currently known to be the northernmost extent of the ranges of at least 6 bat species. Only 2 species of bats, the Northern Myotis (Myotis septentrionalis) and Little Brown Myotis (M. lucifugus), were previously known from the Nahanni National Park Reserve in the southwestern NWT. We used mistnets (15 nights) and AnaBat ultrasound detectors (23 nights) to survey bats in the South Nahanni River Watershed and surrounding area, to undertake the first formal survey of bats in the Northwest Territories. We confirmed the presence of the 2 species formerly documented from the area, as well as an additional 5 species not previously recorded from the region, including: Long-eared Myotis (Myotis evotis), Long-legged Myotis (M. volans), Big Brown Bat (Eptesicus fuscus), Hoary Bat (Lasiurus cinerus), and Eastern Red Bat (L. borealis). Four species were captured in mistnets (Northern Myotis, Little Brown Myotis, Long-eared Myotis and Long-legged Myotis), 1 species was detected acoustically and observed visually in flight (E. fuscus), and 2 species were only detected acoustically (L. cinereus, L. borealis). We documented both sexes for Long-legged, Northern, and Little Brown Myotis; however, reproduction was confirmed only in the latter 2 species. These observations represent the most northerly record (61°N) for Long-eared Myotis and Long-legged Myotis in North America, extending their range approximately 300 km. These 2 species have not been captured elsewhere in NWT, despite recent substantial sampling effort in southcentral NWT. Further sampling effort is needed in southwestern NWT to better understand the distribution of bats in this region.

The occurrence of bats at the northern limit of their ranges in the Northwest Territories (NT), Canada, is not well documented. We provide information on the diversity and distribution of bat species in the NT by synthesizing available records. Before 2006, only 3 species of bats were known to occur in the NT: Little Brown Myotis (Myotis lucifugus), Northern Myotis (M. septentrionalis), and Hoary Bat (Lasiurus cinereus). Focused bat surveys as well as observations of bats reported by residents have added Long-eared Myotis (M. evotis), Long-legged Myotis (M. volans), Big Brown Bat (Eptesicus fuscus), and Silver-haired Bat (Lasionycteris noctivagans), for a total of 7 confirmed species, plus an additional species that is unconfirmed but suspected to occur (Eastern Red Bat, Lasiurus borealis). Range extensions for Little Brown Myotis, Hoary Bat, and Silver-haired Bat are reported. Both Little Brown Myotis and Northern Myotis are reproducing in the NT and are likely abundant in southern NT. Little Brown Myotis has been confirmed to overwinter in the NT and the northern limit of bat hibernation may be further north than previously supposed. Bats are widespread in the southern Central Plains region and gaps in occurrences likely reflect gaps in search effort. Nahanni National Park Reserve has high bat diversity and other parts of southwestern NT are suspected to have similarly high diversity, but have not yet been surveyed. There is evidence that the Eastern Shield region supports bats at relatively low densities. The northern distribution limit of bats in the NT is not known but is expected to occur in the Mackenzie Valley north of 62°N.

Little is known about the distribution of Eastern Red Bats (Lasiurus borealis) at the northwestern edge of their range. We compiled and examined a data set of Eastern Red Bat capture and acoustic records from northern Alberta to examine their distribution, seasonality, and reproductive status near the edge of their range. Acoustic data suggested widespread but patchy distribution across Alberta. The number of captures of Eastern Red Bats in northern Alberta were similar to those of Hoary Bat (Lasiurus cinereus), suggesting that the species may be more common than previously thought. However, we failed to find evidence of reproduction in female Eastern Red Bats in Alberta. Small sample sizes, timing of surveys or difficulty in recognizing juveniles may explain the apparent lack of reproduction. Similar to Hoary Bats, reproductive adult male Eastern Red Bats have been captured with enlarged testes in northern Alberta in August, suggesting sperm production and possibly the start of breeding is taking place there in late summer. In northern Alberta, acoustic monitoring in early spring provided evidence of migratory bats early in the season. A better understanding of seasonal movement patterns and migration, habitat use, and reproduction of Eastern Red Bats in western Canada will require further study. Regardless, our data provide further evidence that the Eastern Red Bat is a more regular member of the bat fauna of northwestern Canada than previously recognized, which may be a result of an expanding distribution.

A review of bat specimens housed at the University of Alaska Museum confirms the occurrence of the Yuma Myotis (Myotis yumanensis) in Southeast Alaska. This represents only the 7th bat species known from the state and its 1st new bat in >40 y. All known specimens of the Yuma Myotis were collected in the early 1990s. Reasons why this species escaped detection until now are discussed and include its close morphological resemblence to the more common and widespread Little Brown Myotis (Myotis lucifugus), the general inaccessibility of much of Southeast Alaska, and a historical paucity of field and specimen-based studies of bats from this region. The presence of the Yuma Myotis in Alaska, while not surprising, suggests that we still have much to learn about the basic biology, ecology, and biogeography of this and other bat species in and around Alaska. Such information is critical if we are to monitor the effects of climate change and other anthropogenic factors on organisms at the limits of their geographic distributions.

Although 5 species of bats have been documented in Southeast Alaska, information on species not of the genus Myotis is derived solely from 4 specimens of the Silver-haired Bat (Lasionycteris noctivagans). We acoustically monitored for bat species that produce low frequency echolocation calls (<30 kHz minimum frequency), specifically Hoary Bat (Lasiurus cinereus), Silver-haired Bat, and Big Brown Bat (Eptesicus fuscus) at 40 sites in 16 locations across Southeast Alaska from 2011 to 2013 using passive bat detectors. The Hoary Bat was not previously known from Alaska, but we recorded 25 call files of this species (of 26,151 low frequency bat files) at 5 sites in northern Southeast Alaska (4 mainland sites and 1 site on Chichagof Island); an additional 110 call files were classified as probable Hoary Bat, but were ambiguous. We recorded 3075 call files that contained echolocation calls diagnostic of Silver-haired Bats; no files had characteristics diagnostic of Big Brown Bats. The rest of the low frequency recordings were identified as probable Silver-haired Bat calls, although Big Brown Bats cannot be ruled out due to the extensive overlap of acoustic characteristics between these 2 species. We recorded Hoary Bats almost exclusively during the autumn migration period. By contrast, Silver-haired Bats were detected throughout the summer active season, indicating at least some individuals are resident in Southeast Alaska. Silver-haired Bat activity was greatest at sites on or near the mainland, with most sites showing peaks of activity in spring, suggesting bats from the interior may be overwintering in the region. Winter recordings suggest Silver-haired Bats (and Big Brown Bats if present) are active to some extent during winter in Southeast Alaska. Understanding the distribution and seasonality of Hoary and Silver-haired Bat activity in Southeast Alaska is a critical 1st step toward identifying their habitat requirements and conservation needs in this region.

We initiated the citizen science-based Alaska Bat Monitoring Project in 2004 to investigate the distribution, habitat use, and seasonal ecology of the Little Brown Myotis in Southcentral, Central, and Western Alaska. As of 2012, we received reports of bats from 252 unique locations across the focus area, including Kotzebue, White Mountain, Saint Michael, and the Semidi Islands, which represent significant range extensions for bats in the state. Ninety-seven percent of 111 roosts were located in human structures. Maternity colonies were identified in 48 locations, all in human structures. The majority of observations were reported in late July, August, and September, but we received observations every month of the year. We received reports of bats in 25 unique locations during the winter period from October to April. Winter bats were all associated with buildings unless observed flying outdoors; no hibernacula in natural substrates were documented. Timing and locations of winter observations imply that bats in the most northerly areas are likely non-migratory and overwinter in human structures, while winter observations in Southcentral Alaska suggest both migratory and non-migratory behavior. Despite the limitations and bias inherent in the data set, these reports represent a significant contribution to our understanding of the distribution and ecology of the Little Brown Myotis in Alaska and provide a basis for future directed research efforts.

Little is known about the ecological relationships of bats of Southcentral Alaska. We used AnaBat II bat detectors, mist-netting, and radio-telemetry to collect preliminary data on the distribution and status of bats on the Chugach National Forest (CNF), their activity patterns, and their roosting and foraging habitats. Myotis spp. were detected at 20 of 25 acoustic sampling sites. Bat activity tended to be higher at water sites than at road or trail sites, and higher in hardwood stands than in conifer stands, although these differences were not statistically significant. Based on data recorded at a maternity roost, the total activity period for bats during July was approximately 5 h per night; no bat activity was observed prior to sunset or after sunrise at any of the sites. Hourly activity was not related to temperature, but activity ended earlier on cooler nights. An adult male Little Brown Myotis (Myotis lucifugus) was tracked to a day-roost in a large Sitka Spruce (Picea sitchensis) snag with sloughing bark. Most female Little Brown Myotis captured at a maternity roost were either lactating or post-lactating. These preliminary findings suggest that bats are common on the CNF, but more research is needed to determine their habitat associations and their responses to disturbances including forest management practices, fire, insect outbreaks, climate change, and disease.

Relatively little is known about bats or bat hibernacula in northern Canada. We were interested in documenting species diversity and seasonal activity of bats in Wood Buffalo National Park, including use of a cave hibernaculum by Little Brown Myotis (Myotis lucifugus), Northern Myotis (Myotis septentrionalis), and Big Brown Bats (Eptesicus fuscus). We used acoustic monitoring and mist netting over 3 y to assess species diversity and seasonal activity. We also recorded cave temperature during hibernation. During the summers of 2010 to 2012, we captured 470 bats including M. lucifugus, M. septentrionalis, and E. fuscus. We identified 2 migratory species via echolocation recordings in 2011: Lasiurus cinereus (Hoary Bat) was recorded in the area from mid-May to early October, and Lasiurus borealis (Eastern Red Bat) from mid-June to early August. Resident bat activity at the hibernaculum was greatest from mid-June to early September. Our findings provide a first approximation of species diversity and describe seasonal activity patterns of bats in Wood Buffalo National Park.

Bats of the temperate region of North America avoid winter by some combination of migration and hibernation at a location that provides the right conditions for minimizing energy expenditure over winter. Such optimal conditions are commonly found underground, and most of the best known hibernacula occur in caves or mines. Where winters are milder, some bat species hibernate in hollows in trees. Haida Gwaii, British Columbia, has the dual distinction of being relatively far north in terms of bat distribution, but with a relatively moderate oceanic climate. We hypothesized that because of the moderate winter temperatures, hibernating in trees could be an option for bats on Haida Gwaii. We used data loggers to monitor temperatures inside potential roost trees during 9 winters between 2002–2003 and 2012–2013. We found that mean winter temperature inside the trees ranged from 2.3–6.5°C, and in most years temperatures either did not drop below freezing or else did so only for short periods of time. We calculated that a 6 g bat would have required between 2.49–2.92 g of fat to hibernate in the tree roosts that we monitored, which is well within the limits that Little Brown Myotis (Myotis lucifugus) are known to accumulate in autumn. Our acoustic data demonstrated that California Myotis (Myotis californicus) were periodically active during all winter months except December, which we view as evidence that this bat hibernates locally either in trees or buildings. The absence of Little Brown Myotis, Keen's Myotis (Myotis keenii) and Silver-haired Bat (Lasionycteris noctivagans) observations during winter suggests that they may either use more common hibernacula, such as caves, or migrate off the islands.

We monitored pre-construction bat acoustic activity from 2007 to 2010 at 4 wind energy sites in northeastern British Columbia to determine nightly and seasonal activity patterns, relative detection rates of different species groups, and the implications for potential fatalities at northern wind facilities. Mean activity rates (August to September) ranged from 2.4 to 79.4 passes per detector-night at the 4 study areas. Activity differed between years for 3 study areas with multi-year data. Nightly variation in activity was pronounced, with wind speed and temperature recorded at meteorological towers explaining 47 to 61% of the variation in nightly activity. Detections were predominantly (60 to 96%) of Myotis bats. Only 1 to 18% of passes recorded at study areas were low-frequency bats (Big Brown Bat, Eptesicus fuscus; Silver-haired Bat, Lasionycteris noctivagans; Hoary Bat, Lasiurus cinereus), with L. cinereus accounting for <1% of the low-frequency passes. No Eastern Red Bats (Lasiurus borealis) were detected. Seasonal activity of low-frequency bats showed no evidence of an influx of spring migrants, but single-night activity spikes in late August and early September were suggestive of autumn migration. Activity of Myotis bats was highest in August and early September, a pattern consistent with resident populations. Results suggest that Myotis species may form a larger proportion of fatalities at northern wind energy facilities than at sites in more temperate regions.

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.

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.