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North American flying squirrels (Glaucomys spp.) are social species that communally den and exhibit home range overlap. However, observations on home range overlap tend to come from live-trapped individuals and it is unknown whether overlap occurs among individuals belonging to the same social network. Since flying squirrels communally den with familiar individuals, their use of artificial nest boxes allows for the radio-collaring and tracking of squirrels within the same social network. We captured and radio-collared northern flying squirrels (G. sabrinus Shaw) found communally denning in nest boxes in the Appalachian Mountains in the eastern United States. We tracked squirrels captured from the same nest box (i.e., nest box groups) to determine home range overlap and subsequent den sharing between familiar individuals within those nest box groups. We found that amount of home range overlap did not differ between male-male, male-female, and female-female dyads, indicating that non-reproductive females and scrotal males are not territorial at the 95% or 50% home range level. Regardless of sex, all dyads had a significantly higher probability of home range overlap (PHR) at the 95% than the 50% home range level (i.e., overlap between squirrels decreases in core areas of their home range). We also found flying squirrels subsequently denned with familiar individuals during 20.9% of occasions post-collaring. Our study provides important information for understanding space use within flying squirrel social networks. Further work should be conducted to determine space use between familiar individuals including seasonal shifts in space use, degree of individual relatedness, and potential territoriality in females denning with young up to and following juvenile dispersal. ; U.S. Fish and Wildlife ServiceUS Fish & Wildlife Service; North Carolina Wildlife Resources Commission; National Park Service; North Carolina Wildlife Resources Commission Pittman-Robertson [W-66-R-1]; US Fish and Wildlife Endangered Species Recovery Implementation [F11AC01265]; National Park Service Southern Appalachian Cooperative Ecosystem Study Unit [P12AC13175]; West Virginia Division of Highways [T699-FLY/SQ-1.00]; Grants-in-Aid for Scientific ResearchMinistry of Education, Culture, Sports, Science and Technology, Japan (MEXT)Japan Society for the Promotion of ScienceGrants-in-Aid for Scientific Research (KAKENHI) [11F01701] Funding Source: KAKEN ; Published version ; U.S. Fish and Wildlife Service; North Carolina Wildlife Resources Commission; National Park Service; West Virginia Division of Highways, Grant/Award Number: T699-FLY/SQ-1.00; North Carolina Wildlife Resources Commission Pittman-Robertson, Grant/Award Number: W-66-R-1; US Fish and Wildlife Endangered Species Recovery Implementation, Grant/Award Number: F11AC01265; National Park Service Southern Appalachian Cooperative Ecosystem Study Unit, Grant/Award Number: P12AC13175 ; Public domain authored by a U.S. government employee

Microhexura montivaga (Spruce-fir Moss Spider) is a federally endangered arachnid endemic to high-elevation montane conifer forests of the southern Appalachian Mountains. The spider is cryptic and difficult to monitor because this species lives in the interface between the bryophyte mat and the rock surface. Since temporary removal of the bryophyte mat is necessary to monitor the spider. surveyors may negatively impact the spider's habitat during monitoring. To help inform survey protocol for this endangered species, we studied reattachment rates of bryophyte mats to rock surfaces after their removal. In 2017, we surveyed sixty 10 cm x 10 cm plots, assigning a plot to either control or treatment (i.e., application of water post-reattachment). We monitored plots for 1 year post-survey to determine reattachment rates. The majority of plots (70%) reestablished after 1 year, whereas 15% did not reattach or showed substantial prolonged (e.g., similar to 1 year) desiccation and 15% completely fell off or had 100% prolonged desiccation and were chlorotic. We found that mat depth and overstory canopy cover had no effect on mat reestablishment, although bryophyte type did. We found no difference between treatment and control plots, suggesting that no treatment is needed for mats to reestablish under the conditions described. Rock slope significantly influenced reestablishment rates, highlighting that surveying bryophyte mats on slopes >80% may diminish or destroy habitat. Further research is needed to determine long-term monitoring effects on the spider and its habitat, especially in relation to disturbance regimes and ecological restoration of Picea rubens (Red Spruce). ; US Fish and Wildlife Service Asheville Field Office (FWS) [4500085700] ; Published version ; We thank Sue Cameron, Fred Coyle, Sheryl Bryan, and Gary Kauffman for their assistance and thoughtful insight over the duration of this project. Foster Levy, Andrew Landsman, and two anonymous reviewers provided comments that improved this manuscript. This research was funded by the US Fish and Wildlife Service Asheville Field Office (FWS Agreement #4500085700). Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the US Government. All work was conducted under US Fish and Wildlife Service Endangered and Threatened Wildlife Permit #YE34778A-2. The authors declare no conflicts of interest relating to this work. ; Public domain authored by a U.S. government employee

Climate-change impacts to Department of Defense (DoD) installations will challenge military mission and natural resource stewardship efforts by increasing vulnerability to flooding, drought, altered fire regimes, and invasive species. We developed biome classifications based on current climate for the coterminous United States using the Holdridge Life Zone system to assess potential change on DoD lands. We validated classifications using comparisons to existing ecoregional classifications, the distribution of major forest types, and tree species in eastern North America. We projected future life zones for mid- and late-century time periods under three greenhouse gas emission scenarios (low-B1, moderate-A1B, and high-A2) using an ensemble of global climate models. To assess installation vulnerability (n = 529), we analyzed biome shifts using spatial cluster analysis to characterize interregional variation, and identified representative installations for subsequent landscape-level analyses. Although mean annual temperatures are expected to increase, installations located in the Northeast, Lake States, and western Great Plains are likely to experience the largest proportional increases in temperature. Accordingly, forest and grassland communities at these installations managed to support a wide range of training, and environmental objectives may be adversely affected by altered disturbance regimes, heat, and moisture stress. However, precipitation is projected to increase in the Northeast and Lake States mitigating some effects of increased temperatures on biological communities. Given the uncertain response to climate change in different ecoregions, additional environmental and stewardship attributes are needed within a decision-support framework to understand vulnerabilities and provide appropriate responses. ; U.S. Army Engineer Research and Development Center's Environmental Quality and Installation Research Program ; This project was funded by the U.S. Army Engineer Research and Development Center's Environmental Quality and Installation Research Program. ; Public domain authored by a U.S. government employee

In eastern North America, white-tailed deer (Odocoileus virginianus) can have profound influences on forest biodiversity and forest successional processes. Moderate to high deer populations in the central Appalachians have resulted in lower forest biodiversity. Legacy effects in some areas persist even following deer population reductions or declines. This has prompted managers to consider deer population management goals in light of policies designed to support conservation of biodiversity and forest regeneration while continuing to support ample recreational hunting opportunities. However, despite known relationships between herbivory intensity and biodiversity impact, little information exists on the predictability of herbivory intensity across the varied and spatially diverse habitat conditions of the central Appalachians. We examined the predictability of browsing rates across central Appalachian landscapes at four environmental scales: vegetative community characteristics, physical environment, habitat configuration, and local human and deer population demographics. In an information-theoretic approach, we found that a model fitting the number of stems browsed relative to local vegetation characteristics received most (62%) of the overall support of all tested models assessing herbivory impact. Our data suggest that deer herbivory responded most predictably to differences in vegetation quantity and type. No other spatial factors or demographic factors consistently affected browsing intensity. Because herbivory, vegetation communities, and productivity vary spatially, we suggest that effective broad-scale herbivory impact assessment should include spatially-balanced vegetation monitoring that accounts for regional differences in deer forage preference. Effective monitoring is necessary to avoid biodiversity impacts and deleterious changes in vegetation community composition that are difficult to reverse and/or may not be detected using traditional deer-density based management goals. ; Wildlife and Sport Fish Restoration Program [WE99, 2012-13694] ; This work was financially supported by the Wildlife and Sport Fish Restoration Program, Project WE99, Contract 2012-13694 to Virginia Tech. ; Public domain authored by a U.S. government employee

Because moderate to over-abundant white-tailed deer (Odocoileus virginianus) herbivory impacts biodiversity and can alter community function, ecological benchmarks of herbivory impact are needed to assess deer impacts. We evaluated spatial patterns of deer herbivory and their relation to herbivory assessment by evaluating woody vegetation along 20 transects at each of 30 sites spread across a wide range of deer herd densities and vegetative condition throughout the biodiverse Appalachian Mountains of Virginia, USA. Surprisingly, herbivory patterns and the availability of woody forage generally were unchanged among physiographic regions and land use diversity classes. However, some relationships between browsing pattern and vegetation varied with scale. The total quantity of vegetation browsed on a given site and at the transect scale were related positively to the availability of forage, as the proportion of stems browsed decreased as stem density increased. However, this was only true when all stems were considered equally. When stem densities by species were weighted for deer preference, the proportion of stems browsed had no relationship or increased with stem density. Compared to the value from all transects sampled, on average, the mean of >= 3 transects within a site was within 0.1 of the browsing ratio and stem densities were within 0.5 stems m(-2). Our results suggest that one transect per square kilometer with a minimum of three transects may be sufficient for most browsing intensity survey requirements to assess herbivory impacts in the Appalachian region of Virginia. Still, inclusion of spatial factors to help partition variation of deer herbivory potentially may allow for improved precision and accuracy in the design of field herbivory impact assessment methods and improve their application across various landscape contexts. ; U.S. Fish and Wildlife Service through the Wildlife and Sport Fish Restoration Program [WE99]; Virginia Department of Game and Inland Fisheries ; We thank the Virginia Department of Game and Inland Fisheries for sponsoring this project using funds provided from the U.S. Fish and Wildlife Service through the Wildlife and Sport Fish Restoration Program, project WE99. Specifically we thank N. Lafon, M. Knox, J. Bowman, and D. Steffen for their comments and support. We also thank J. Parkhurst and M. Cherry for their comments on this manuscript and C. Parker for his help with field data collection. ; Public domain authored by a U.S. government employee

Little is known about hypogeous, sequestrate fungi (i.e., truffles) in the eastern United States. Since the fruiting bodies of these fungi are part of the diet of multiple rodent species, filling data gaps is important to understanding more about truffle species distribution and habitat associations. During a microhabitat study on radio-collared Glaucomys sabrinus fuscus (Virginia Northern Flying Squirrel) in 2013, we opportunistically sampled truffles at small-mammal digs and scratches within our microhabitat plots. All sampling was conducted within known squirrel-foraging home ranges. We found 3 Elaphomyces species: E. macrosporus, E. verruculosus, and E. americanum. Our observations of E. macroporus are the first from West Virginia. Herein, we describe the microhabitat associations for each fungal species. We suggest using small-mammal digs and scratches as potential indicators to opportunistically gather more information on truffle species in coniferous forests of the eastern United States. ; West Virginia Division of Highways [T669-FLY/SQ-1.00] ; Funding for this study was provided by West Virginia Division of Highways (Grant #T669-FLY/SQ-1.00). D. Richardson, M. Gilley, and 2 anonymous reviewers provided comments that improved this manuscript. The use of any trade, product, or firm names does not imply endorsement by the US government. The authors state no conflicts of interest in regard to this wor k. ; Public domain authored by a U.S. government employee

Forest roosting bats use a variety of ephemeral roosts such as snags and declining live trees. Although conservation of summer maternity habitat is considered critical for forest-roosting bats, bat response to roost loss still is poorly understood. To address this, we monitored 3 northern long-eared bat (Myotis septentrionalis) maternity colonies on Fort Knox Military Reservation, Kentucky, USA, before and after targeted roost removal during the dormant season when bats were hibernating in caves. We used 2 treatments: removal of a single highly used (primary) roost and removal of 24% of less used (secondary) roosts, and an un-manipulated control. Neither treatment altered the number of roosts used by individual bats, but secondary roost removal doubled the distances moved between sequentially used roosts. However, overall space use by and location of colonies was similar pre- and post-treatment. Patterns of roost use before and after removal treatments also were similar but bats maintained closer social connections after our treatments. Roost height, diameter at breast height, percent canopy openness, and roost species composition were similar pre- and post-treatment. We detected differences in the distribution of roosts among decay stages and crown classes pre- and post-roost removal, but this may have been a result of temperature differences between treatment years. Our results suggest that loss of a primary roost or 20% of secondary roosts in the dormant season may not cause northern long-eared bats to abandon roosting areas or substantially alter some roosting behaviors in the following active season when tree-roosts are used. Critically, tolerance limits to roost loss may be dependent upon local forest conditions, and continued research on this topic will be necessary for conservation of the northern long-eared bat across its range. Data: http://hdl.handle.net/10919/50954 ; Peer Reviewed

Forest roosting bats use a variety of ephemeral roosts such as snags and declining live trees. Although conservation of summer maternity habitat is considered critical for forest-roosting bats, bat response to roost loss still is poorly understood. To address this, we monitored 3 northern long-eared bat (Myotis septentrionalis) maternity colonies on Fort Knox Military Reservation, Kentucky, USA, before and after targeted roost removal during the dormant season when bats were hibernating in caves. We used 2 treatments: removal of a single highly used (primary) roost and removal of 24% of less used (secondary) roosts, and an un-manipulated control. Neither treatment altered the number of roosts used by individual bats, but secondary roost removal doubled the distances moved between sequentially used roosts. However, overall space use by and location of colonies was similar pre- and post-treatment. Patterns of roost use before and after removal treatments also were similar but bats maintained closer social connections after our treatments. Roost height, diameter at breast height, percent canopy openness, and roost species composition were similar pre- and post-treatment. We detected differences in the distribution of roosts among decay stages and crown classes pre- and post-roost removal, but this may have been a result of temperature differences between treatment years. Our results suggest that loss of a primary roost or ≤ 20% of secondary roosts in the dormant season may not cause northern long-eared bats to abandon roosting areas or substantially alter some roosting behaviors in the following active season when tree-roosts are used. Critically, tolerance limits to roost loss may be dependent upon local forest conditions, and continued research on this topic will be necessary for conservation of the northern long-eared bat across its range.

Many terrestrial vertebrate species are exhibiting geographic distribution changes including poleward range limit shifts in response to increases in regional temperature. Bats are a highly mobile taxa capable of rapid responses to changes in abiotic or biotic conditions. In North America, recent extralimital records of the non-hibernating Lasiurus seminolus (Seminole bat) have been attributed to climate change, however such attributions remain speculative and potentially subject to sampling bias in the form of increased recent sampling efforts at latitudes north of the historical range. We used historical occurrence records and simple environmental variables within a Maxent modeling framework to model the historical distribution of suitable areas for this species. We transferred the model using near current environmental conditions and measured the ability of the model to capture the apparent expansion in distribution using recent extralimital occurrence records. Our model transferred well over time concluding that the distribution expansion may be largely attributed to increasing minimum temperatures. We used the model to forecast the expansion in distribution of suitable areas at three 20-year intervals and various climate change scenarios and provide extrapolation risk maps for each scenario. Although increasing temperatures may increase potentially occupiable areas, the species is associated with forests and often roosts in pines (Pinus spp.). This suitable habitat is more limited to the northwest of the species' range, which may constrain the future species expansion despite favorable temperatures. We demonstrated this effect by mapping limiting factors through future climate change scenarios. We discovered a broad shift of effects that constrained the distribution from minimum temperature to an abundance metric of evergreen cover type as time and climate change intensity increased. Although uncertainties exist, we predict further expansion of the Seminole bat widely over the next 60 years across the eastern United States where suitable habitat and climate conditions converge. Our results appear consistent with other bat species showing similar range extensions and in turn provide further evidence that bats may serve as bioindicators of global change. ; Virginia Department of Wildlife Resources [AT-63514, EP2489066] ; Published version ; We thank S. Loeb and M. B. Adams for earlier reviews of this manuscript. Additionally, we thank R. Odom for miscellaneous collaborative efforts and E. A. Frimpong and S. N. Winter for statistical modeling advice. This work was supported by the Virginia Department of Wildlife Resources contracts AT-63514 and EP2489066 to Virginia Polytechnic Institute and State University Department of Fish and Wildlife Conservation Manipulation and filtering of occurrence data, manipulating and calculating environmental raster datasets, and all Maxent modeling were performed in R (R Core Team, 2019) and associated codes are available on a GitHub repository (github.com/mtrue2/seminolebats) for reproducibility purposes. Questions about codes should be directed to the corresponding author (mtrue@vt.edu). ; Public domain authored by a U.S. government employee

Changes to hat distribution and habitat associations at the local to sub-landscape scale in the post white-nose syndrome (WNS) environment have received little attention to date despite being critical information for managers. To better understand the spatial nature of hat population declines, we modelled both activity patterns and occupancy from acoustic surveys for the Myotis lucifugus (little brown hat) on Fort Drum Military Installation in New York, USA over 15 summers (2003-2017) that span the pre-WNS, WNS-advent (2008) and post-WNS periods, using a set of generalized linear mixed models and geospatial analysis. Our best supported model indicated significant differences between years with significant declines in activity post-WNS. M. lucifugus activity was most closely associated with woody wetland habitats over the study period, however, the spatial patterns of high activity areas were variable over years, with the areal extent of these high activity areas decreasing post-WNS. Our best supported occupancy model varied by year. However, the null occupancy model [Psi(.)] was either competing (within 2 Delta AIC units) or was the best supported model. Meaning that none of our environmental variables seemed to impact occupancy, and when they did, these differences were not significant. There was high disagreement between our relative activity models and predictions compared to our occupancy models, suggesting that geographic spatial scale and the resolution of the data impacts model outcome. Our results indicate that continued acoustic monitoring of hat species in the Northeast to assess ongoing temporal and spatial changes in habitat associations and to provide direction for future mist-netting studies should rely more on relative activity as the metric of choice rather than site occupancy. ; U.S Army Corps of EngineersUnited States Department of Defense [W9126G-15-2-0005]; Southern Appalachian Cooperative Ecosystems Study Unit Program ; This work was supported by the U.S Army Corps of Engineers [W9126G-15-2-0005] through the Southern Appalachian Cooperative Ecosystems Study Unit Program. We thank C. Whitman for field assistance. Earlier drafts of this manuscript were reviewed by B. Carstensen. and K. Powers. The use of any trade, product or firm names does not imply endorsement by the U.S. government. ; Public domain authored by a U.S. government employee

With the declines in abundance and changing distribution of white-nose syndrome-affected bat species, increased reliance on acoustic monitoring is now the new "normal." As such, the ability to accurately identify individual bat species with acoustic identification programs has become increasingly important. We assessed rates of disagreement between the three U.S. Fish and Wildlife Service-approved acoustic identification software programs (Kaleidoscope Pro 4.2.0, Echoclass 3.1, and Bat Call Identification 2.7d) and manual visual identification using acoustic data collected during summers from 2003 to 2017 at Fort Drum, New York. We assessed the percentage of agreement between programs through pairwise comparisons on a total nightly count level, individual file level (e.g., individual echolocation pass call file), and grouped maximum likelihood estimate level (e.g., probability values that a species is misclassified as present when in fact it is absent) using preplanned contrasts, Akaike Information Criterion, and annual confusion matrices. Interprogram agreement on an individual file level was low, as measured by Cohen's Kappa (0.2-0.6). However, site-night level pairwise comparative analysis indicated that program agreement was higher (40-90%) using single season occupancy metrics. In comparing analytical outcomes of our different datasets (i.e., how comparable programs and visual identification are regarding the relationship between environmental conditions and bat activity), we determined high levels of congruency in the relative rankings of the model as well as the relative level of support for each individual model. This indicated that among individual software packages, when analyzing bat calls, there was consistent ecological inference beyond the file-by-file level at the scales used by managers. Depending on objectives, we believe our results can help users choose automated software and maximum likelihood estimate thresholds more appropriate for their needs and allow for better cross-comparison of studies using different automated acoustic software. ; Fort Drum Military Installation through U.S Army Corps of Engineers [W9126G-15-2-0005] ; The Fort Drum Military Installation through U.S Army Corps of Engineers contract W9126G-15-2-0005 via the Southern Appalachia Cooperative Ecosystems Study Unit Program supported this work. We thank J. Rodrigue and C. Whitman for field assistance. Earlier drafts of this article were reviewed by B. Carstensen. The comments of the Associate Editor and three anonymous reviewers substantially improved this article. ; Public domain authored by a U.S. government employee

Previous acoustic surveys, netting, and count data have shown that overall bat activity patterns have shifted among most species between pre- and post-white-nose syndrome (WNS) years in much of North America where WNS has occurred. However, the significance of these changes is based on the species-specific susceptibility to WNS. We used acoustically recorded echolocation passes obtained at Fort Drum, New York to describe changes in bat activity pre-WNS (2004-2007) to post-WNS (2008-2018). We examined seasonal and yearly changes in bat activity as they relate to the presence of WNS at hibernacula near (<25 km) Fort Drum. A priori, we expected that overall activity for communal hibernating species would be less in years following WNS, and migratory bats or those hibernating bats that are less affected by WNS would show no response or a positive response, due to niche relaxation/competitive release. Our results indicated both an overall and seasonal decrease in activity for Myotis spp. post-WNS. For WNS-susceptible species, our results reflect the high level of mortality in regional winter hibernacula post-WNS and possibly variable reproductive effort and recruitment thereafter. Although migratory bats did show increases in post-WNS activity throughout the summer, we found little evidence that community displacement was occurring on a nightly level by any species. The continuous spread of WNS across North America has had strong negative effects on bat populations of affected species, and our research identifies how individual species (both impacted and non-impacted) respond to WNS. Published by Elsevier B.V. ; U.S Army Corps of Engineers' Cooperative Agreement through the Southern Appalachian Cooperative Ecosystems Study Unit Program [W9126G-15-2-0005] ; This work was supported by the U.S Army Corps of Engineers' Cooperative Agreement W9126G-15-2-0005 through the Southern Appalachian Cooperative Ecosystems Study Unit Program to the Virginia Tech Department of Fish and Wildlife Conservation. We thank C. Whitman for field assistance. Earlier drafts of this manuscript were reviewed by B. Carstensen, L. Coleman and two anonymous reviewers. ; Public domain authored by a U.S. government employee

Context Understanding habitat selection is important for determining conservation and management strategies for endangered species. The Carolina northern flying squirrel (CNFS; Glaucomys sabrinus coloratus) is an endangered subspecies found in the high-elevation montane forests of the southern Appalachians, USA. The primary use of nest boxes to monitor CNFS has provided biased information on habitat use for this subspecies, as nest boxes are typically placed in suitable denning habitat. Aims We conducted a radio-telemetry study on CNFS to determine home range, den site selection and habitat use at multiple spatial scales. Methods We radio-collared 21 CNFS in 2012 and 2014–15. We tracked squirrels to diurnal den sites and during night-time activity. Key results The MCP (minimum convex polygon) home range at 95% for males was 5.2±1.2ha and for females was 4.0±0.7. The BRB (biased random bridge) home range at 95% for males was 10.8±3.8ha and for females was 8.3±2.1. Den site (n=81) selection occurred more frequently in montane conifer dominate forests (81.4%) vs northern hardwood forests or conifer–northern hardwood forests (9.9% and 8.7%, respectively). We assessed habitat selection using Euclidean distance-based analysis at the 2nd order and 3rd order scale. We found that squirrels were non-randomly selecting for habitat at both 2nd and 3rd order scales. Conclusions At both spatial scales, CNFS preferentially selected for montane conifer forests more than expected based on availability on the landscape. Squirrels selected neither for nor against northern hardwood forests, regardless of availability on the landscape. Additionally, CNFS denned in montane conifer forests more than other habitat types. Implications Our results highlight the importance of montane conifer to CNFS in the southern Appalachians. Management and restoration activities that increase the quality, connectivity and extent of this naturally rare forest type may be important for long-term conservation of this subspecies, especially with the impending threat of anthropogenic climate change.

New technologies allow for more efficient and effective monitoring of rare or elusive species. However, standardizing protocol to ensure high detection rates is important prior to widespread use of a new technique. The use of ultrasonic acoustic detectors to survey for flying squirrels (Glaucomys spp.) is a novel method that is more efficient than traditional methods. However, certain methodologies for this technique still need to be refined. During 2015, we conducted a seasonal and habitat quality study on the endangered Carolina northern flying squirrel (G. sabrinus coloratus) in western North Carolina, USA. Our seasonal study examined differences in probability of detection (POD) and latency to detection (LTD) at 30 high-quality sites across 10 survey nights in spring, summer, and autumn. The habitat quality study focused on POD and LTD among 15 sites with varying habitat quality (5 High, 5 Medium, 5 Low) across 20 survey nights. We found POD similar between seasons, with POD 15-20% greater during spring. The LTD was comparable among seasons. We found that POD and LTD varied at sites with different habitat quality. The POD was similar between High and Medium sites (0.26 +/- 0.04 SE and 0.29 +/- 0.05, respectively), but greater than Low sites (0.02 +/- 0.02). The LTD was not different among sites with differing habitat quality, although LTD at High sites was 2.7 and 4.5 times lower than Medium and Low sites, respectively. Trill calls, the most distinctive species-specific call type produced by species of flying squirrels, was recorded at greater rates in spring versus other times of the year. Our results indicate flying squirrels can be surveyed during any season, although habitat quality needs to be considered when determining survey length. For Carolina northern flying squirrel, the optimal time to perform acoustic surveys is during the spring season for 6-10 survey nights at sites with high or medium habitat quality. (c) 2020 The Wildlife Society. ; North Carolina Pittman-Robertson grant [W-66-R-1]; U.S. Fish and Wildlife Endangered Species Recovery Implementation grant [F11AC01265]; National Park Service Southern Appalachian Cooperative Ecosystem Study Unit [P12AC13175] ; We would like to thank K. Weeks, S. Cameron, M. Crockett, M. McCombs, S. Bryan, E. Corey, R. McGraw, B. Cherry, P. Super, J. Yarkovich, and B. Stiver for logistical support. S. Higdon, K. Parker, A. Garnish, N. Yates, and H. B. Hound provided assistance with field work and data management. The Southern Appalachian Highlands Conservancy provided housing. North Carolina Pittman-Robertson grant #W-66-R-1, U.S. Fish and Wildlife Endangered Species Recovery Implementation grant #F11AC01265, and National Park Service Southern Appalachian Cooperative Ecosystem Study Unit agreement #P12AC13175 provided funding for this project. This research was conducted under North Carolina Wildlife Resources Commission Endangered Species Permit #14-ES00401, U.S. Fish & Wildlife Service Endangered Species Research Recovery Permit #TE34778A-0, North Carolina State Parks Permit #2015-0023, and National Park Service Permit #GRSM-2015-SCI-1226. Associate Editor P. Neuhaus, K. Weeks, S. Hirt, and 2 anonymous reviewers provided comments that helped improve this manuscript. The authors of this manuscript have no known conflicts of interest. The use of trade, product, or firm names does not imply endorsement by the U.S. government. ; Public domain authored by a U.S. government employee