Scholarly Works, Conservation Management Institute

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Distribution of Northern Long-eared Bat Summer Habitat on the Monongahela National Forest, West Virginia
De La Cruz, Jesse L.; Ford, W. Mark; Jones, Shane; Johnson, Joshua B.; Silvis, Alexander (2023-03)
Species distribution models enable resource managers to avoid and mitigate impacts to, or enhance habitat of, target species at the landscape level. Persistent declines of northern long-eared bats (Myotis septentrionalis) due to white-nose syndrome have made acquisition of contemporary data difficult. Therefore, use of legacy data may be necessary for creation of species distribution models. We used historical roost and capture records, both individually and in combination, to assess the distribution and availability of northern long-eared bat habitat across the 670,000-ha Monongahela National Forest (MNF), West Virginia, USA. We created random forest presence/pseudo-absence models to examine influences of various biotic and abiotic predictors on both roosting and foraging presence locations of northern long-eared bats. Predicted northern long-eared bat habitat was abundant (43.1% of the MNF) and widely dispersed. Generally, all models suggested that northern long-eared bat habitat was characterized by interior forests containing linear edge features. We observed only 3.4% spatial overlap of habitat based on complete model agreement, but 38.5% of all habitat areas resulted from agreement between capture-only and combination models. Our models provide important assessments of habitat availability necessary for addressing state and federal conservation requirements on the MNF and adjacent eastern West Virginia mountains.
Distribution of Summer Habitat for the Indiana Bat on the Monongahela National Forest, West Virginia
De La Cruz, Jesse L.; Ford, W. Mark; Jones, Shane; Johnson, Joshua B.; Silvis, Alexander (2023-03)
Hierarchical conservation and management of Indiana bat (Myotis sodalis) habitat may benefit from use of species distribution models. White-nose syndrome has caused additional declines for this endangered bat, requiring use of historical presence locations for habitat-related analyses. We created random forest presence/pseudo-absence models to assess the distribution and availability of Indiana bat habitat across the 670,000-ha Monongahela National Forest (MNF), West Virginia, USA. We collated historical roost and capture locations, both individually and in combination, to examine impacts of various biotic and abiotic predictors on roosting and foraging habitat of Indiana bats. Our final concordance map suggests that Indiana bat habitat was abundant (37.2% of the MNF) but localized, with predicted suitable areas often associated with edges of dry-calcareous forests. We observed significant variation between models, with the capture-only model independently identifying the greatest amount of potential habitat (47.8%). However, 21.9% of all potential Indiana bat habitat was identified by complete inter-model agreement. Our SDM outputs may assist land managers in identifying avoidance areas and new survey sites (i.e., capture and acoustic sampling) to support forest management activities.
Distribution Probability of the Virginia Northern Flying Squirrel in the High Allegheny Mountains
Ford, W. Mark; Diggins, Corinne A.; De La Cruz, Jesse L.; Silvis, Alexander (2022-03)
In the central Appalachians of Virginia and West Virginia, the Virginia northern flying squirrel (Glaucomys sabrinus fuscus; VNFS) is a subspecies of northern flying squirrel generally associated with red spruce (Picea rubens)-dominated forests at high elevations. Listed as endangered by the U.S. Fish and Wildlife Service from 1985 to 2013, the VNFS currently is the subject of a 10-year post-delisting assessment. Still considered a state-listed species in Virginia and a species of greatest conservation need in West Virginia, the VNFS serves as a focal target for red spruce restoration activities in the High Allegheny Region (HAR) of the two states. Owing to the cryptic nature of VNFS and its low detection probability in live-capture surveys, managers in the region rely on habitat models to assess probable presence. Using long-term nest-box, live-trapping, and radio-telemetry data matched with updated high elevation forest-type coverage data for the region, we created a new VNFS resource selection function and spatial coverage map. Inputting red spruce cover, increasing elevation, and decreasing landform index (increasing site shelteredness) composed the best model explaining VNFS occurrence. The calculated amount of low-quality habitat was congruent with previous modeling efforts; however, inclusion of more VNFS occurrence records in the current effort indicated that previous efforts substantially underestimated the amount (>400%) of extant high quality VNFS habitat. We estimate the HAR to contain approximately 197,952 ha with ≥0.50 predicted probability of occurrence of VNFS. In addition to potentially improving current and future VNFS live-capture surveys, with this model managers may better target forests for red spruce restoration to increase high elevation forest ecological integrity and to improve habitat patch connectedness for VNFS.
Landscape Characteristics Related to Use of Artificial Roosts by Northern Long-eared Bats in North-central West Virginia
De La Cruz, Jesse L.; Ward, Ryan L.; Schroder, Eric S. (Humboldt Field Research Institute, 2018-09-01)
In the eastern US, research is needed on the establishment and evaluation of conservation measures for forest-dwelling bats, in general, and for the newly listed Myotis septentrionalis (Northern Long-Eared Bat), in particular. Our objectives were to evaluate the overall use of 3 artificial roosting structures-rocket box, nursery box, and artificial bark-by bats and to relate this use to local landscape characteristics in north-central West Virginia. We monitored 306 structures during summer 2016 and detected use (i.e., presence of guano, visual identification, capture of bats) at 132 (43%) roosts, of which 55 (42%) were confirmed, through capture or visual identification, to contain Northern Long-eared Bats. Nursery boxes were used more than expected based on availability (60%), but rocket boxes accounted for 40 (73%) of the roosts confirmed to be occupied by Northern Long-eared Bats, with 70% being used by maternity colonies of this species. We utilized binomial generalized linear models and an information theoretic approach to examine use of artificial roosts by maternity colonies of Northern Long-eared Bats. Our best-supported model differentiating structures occupied by maternity colonies from those that housed individual bats showed relationships to elevation, slope, area solar radiation, and distance to streams and large (>200 ha) forests. Our study provides initial guidance for land and wildlife managers on implementing an effective conservation and management technique for bats within this region.
Seasonal Activity Patterns of Northern Long-eared Bats at Hibernacula in Western Virginia
De La Cruz, Jesse L.; Reynolds, Richard J.; Orndorff, Will; Malabad, Thomas; Kosic Ficco, Katarina; Powers, Karen E.; Ford, W. Mark (2024)
Understanding the relationships of biotic and abiotic factors to seasonal activity at hibernacula is important for the conservation of bats impacted by white-nose syndrome (WNS). Research on the relative and probable activity patterns of the federally endangered northern long-eared bat (Myotis septentrionalis) primarily has focused on summer maternity colonies, whereas surveys at hibernacula have traditionally relied on external capture and internal counts. We used passive acoustic monitoring to assess the relative and probable activity of northern long-eared bats at 13 hibernac- ula in western Virginia, from August 2020 to May 2022. Northern long-eared bats were most active near hibernacula during warmer weeks of the fall swarm and spring emergence, when rainfall was low. Similarly, the probability of northern long-eared bat activity was highest near hibernacula during the spring/summer season. However, unlike relative activity, the likelihood of recording northern long-eared bats was associated with more heteroge- neous, interior forests. Our results suggest that northern long-eared bat activity largely follows the described pre-WNS hibernation phenology of the species. Therefore, acoustical surveys to monitor northern long-eared bat populations at hibernacula should focus on entrances during peak activity periods (mid-April and early September), rather than the nearby landscape. Finally, management to promote resource-rich foraging habitat adjacent to hibernacula for use during swarming and emergence may increase survival during hibernation, fitness for spring migration, and ultimately, improve the reproductive success of northern long-eared bats in western Virginia.
Seasonal Activity Patterns of Northern Long-eared Bats on the Coastal Mid-Atlantic
De La Cruz, Jesse L.; Kalen, Nicholas J.; Barr, Elaine L.; Thorne, Emily D.; Silvis, Alexander; Reynolds, Richard J.; Ford, W. Mark (2024)
Conservation of bats declining from white-nose syndrome (WNS) impacts requires an understanding of both temporal and landscape-level habitat relationships. Traditionally, much of the research on bat ecology has focused on behavior of summer maternity colonies within species’ distribution cores, including that of the endangered northern long-eared bat (Myotis septentrionalis). To further our knowledge of this species, we evaluated multi-season activity patterns in eastern North Carolina and Virginia, including areas where populations were recently discovered. We used passive acoustic monitoring to assess relative and probable activity of northern long-eared bats from October 2016 to August 2021. Northern long-eared bat relative activity was greatest in areas containing greater proportions of woody wetlands and upland pine-dominated evergreen forests. However, the likelihood of recording northern long-eared bats was associated with smaller proportions of woody wetlands and open water resources. Furthermore, we observed a higher probability of recording northern long-eared bats during non-winter seasons. Probable activity was greatest at temperatures be- tween 10 and 25 C, potentially highlighting an optimal thermoneutral zone for the species regionally. Relative activity of northern long-eared bats on the Coastal Plain of Virginia and North Carolina was primarily driven by cover features, whereas probable activity was driven by a combination of cover features, seasonality, and temperature. Therefore, acoustical surveys for this species may be most effective when targeting woody wetlands adjacent to upland forests, particularly upland pine-dominated evergreen stands, during moderate temperatures of non-winter seasons (1 April–15 November). Moreover, conservation of a diverse mosaic of woody wetlands juxtaposed by upland forests may promote both roosting and overwintering habitat, thereby enhancing overwintering survival, maternity colony establishment, and ultimately, successful reproduction of northern long-eared bats.
Second Guessing the Maximum Likelihood Estimator Values for Bat Surveys
Ford. W. Mark; De La Cruz, Jesse L.; Thorne, Emily D.; Silvis, Alexander; Armstrong, Michael P.; King, R. Andrew (2024)
The U.S. Fish and Wildlife Service allows acoustical surveys and automated identification software to determine the presence of the endangered northern long-eared bat (Myotis septentrionalis) and Indiana bat (Myotis sodalis). Analytical software is required to assess presence probability on a site-night basis using a maximum likelihood estimator (MLE) that accounts for interspecific bat misclassification rates. The current standard for occupancy is a returned MLE P-value < 0.05 at the nightly level irrespective of the number of files identified as either northern long-eared bats or Indiana bats. These MLE P-values can vary based on presence of other bat species with similar calls and the relative proportions of all species recorded. Accordingly, there is concern that with few nightly northern long-eared bat or Indiana bat recordings or the presence of large numbers of high frequency bats, false-negative findings from a swamping effect could result. Using data collected in 2020–2021 by the U.S. Fish and Wildlife Service to set nationwide acoustic monitoring guidelines, we examined the relationship of returned software MLE P-values from 4873 site-nights of acoustic detector data relative to nightly counts of northern long-eared bats and Indiana bats, overall counts of other high-frequency bats, and habitat cover type. For both northern long-eared bats and Indiana bats, nights with one or more echolocation pass files identified as either species but above the MLE P-value threshold largely occurred where nightly counts of the target species was <15 and their proportion to the count of high-frequency bat species was low. We followed this analysis with a simulation using a known call library and observed similar patterns. Accordingly, with few nightly echolocation passes, post-hoc visual assessment following automated software identification easily could be undertaken. Evidence of swamping by other high-frequency species causing positive file identification creating false-negative or false-positives of northern long-eared bats and Indiana bats was not apparent at nightly counts of either species > 10.
Southern Fox Squirrel and Eastern Gray Squirrel Interactions in a Fire-maintained Ecosystem
Guill, Marissa H.; De La Cruz, Jesse L.; Puckett, Marc; Klopfer, Scott D.; Martin, Brandon; Ford, W. Mark (2024)
Southern fox squirrels (Sciurus niger niger) have been declining due to habitat fragmentation, cover type conversion, and fire suppression in the Southeast. A decrease in growing season burns has led to hardwood encroachment and forest mesophication that benefit the competing eastern gray squirrels (S. carolinensis). In the southern Coastal Plain and Piedmont of Virginia, these pattern raises the question of whether gray squirrels are competitively excluding southern fox squirrels in these altered landscapes. From October 2019 to October 2020, we conducted continual camera trapping for southern fox squirrels and gray squirrels on the Big Woods/Piney Grove Complex (BWPGC) and at Fort Barfoot (FB) in the Coastal Plain and lower Piedmont of Virginia, respectively. Both sites are among the few areas that still contain large, intact pine savanna and mixed-pine hardwood forests in southeastern Virginia. We used two-species occupancy modeling to investigate occupancy estimates of southern fox squirrels and possible competition with gray squirrels, based on detection histories collected from camera traps on BWPGC and FB. We then conducted informed single-species occupancy modeling to estimate the necessary level-of effort (LOE) required to determine the probable absence of southern fox squirrels at sampling sites in the region. No fox squirrels were observed at FB. Our top, two species occupancy model showed that gray squirrel occupancy increased with increasing time since last burn. However, southern fox squirrel occupancy, in the absence of gray squirrels, decreased with increasing time since last burn. Gray squirrels typically inhabited hardwood-dominant closed canopy areas whereas southern fox squirrels did so at BWPGC only in the absence of gray squirrels. This suggests that southern fox squirrels are selecting areas on BWPGC based on resource needs and possibly competition with gray squirrels. A single-season occupancy model confirmed that southern fox squirrel occupancy decreased with time since the last burn. Our LOE analysis indicated that seven consecutive days of camera trapping without a detection would provide 90% confidence of the subspecies’ absence in areas burned two or more years prior to sampling. Southern fox squirrels may benefit from increased short-rotation burns to maintain or enhance pine-hardwood savannas and pine-hardwood savanna ecotones in southeastern Virginia.
Summer-Habitat Suitability Modeling of Myotis sodalis (Indiana Bat) in the Eastern Mountains of West Virginia
De La Cruz, Jesse L.; Ward, Ryan L. (Humboldt Field Research Institute, 2016-03)
Little information exists with regard to suitable summer habitat of Myotis sodalis (Indiana Bat) in West Virginia. Our research objectives were to use ultrasonic acoustic equipment and automated identification software to collect presence data for Indiana Bats and to examine habitat characteristics and availability across the local landscape. We used a maximum entropy (MAXENT) approach to determine if the distribution of various ecological factors such as landuse/landcover, forest fragmentation, aspect, area solar radiation, slope, proximity to permanent water, and elevation influenced foraging-habitat suitability of Indiana Bats. We sampled across the 1160-ha Camp Dawson Collective Training Area in Preston County, WV, to determine Indiana Bat presence. We employed the collected presence data to examine habitat suitability within a 16,151-ha study area encompassing the training facility. Based on MAXENT results, we characterized highly suitable Indiana Bat habitat as including large tracts of contiguous forest cover (>200 ha) associated with low to modest slopes (<20°), road corridors, and areas of high solar radiation (>5.5 x 105 WH/m2). High (81–100%) and medium-high (61–80%) suitability classes were uncommon across the landscape (0.6% and 2.7%, respectively), with the broad medium-to-high suitability classes (41–100%) collectively comprising only 11.4% of the study area. Elevation (m) and aspect contributed little to the model and displayed low permutation importance that did not vary notably from the corresponding percent contribution. These variables, along with close proximity to permanent water (≤200 m away), are likely not limiting ecological factors. The results of this study supplement current knowledge of summer habitat of the Indiana Bat and provide land and wildlife managers localized guidance on conservation priorities within the region.
Terrestrial Wildlife in the Post-mined Appalachian Landscape: Status and Opportunities
Lituma, Christopher M.; Cox, John J.; Spear, Stephen F.; Edwards, John W.; De La Cruz, Jesse L.; Muller, Lisa I.; Ford, W. Mark (Springer, 2021)
Coal mining is an anthropogenic stressor that has impacted terrestrial and semi-aquatic wildlife in the Appalachian Plateau since European settlement. Creation of grassland and early-successional habitats resulting from mining in a forested landscape has resulted in novel, non-analog habitat conditions. Depending on the taxa, the extent of mining on the landscape, and reclamation practices, effects have ranged across a gradient of negative to positive. Forest-obligate species such as woodland salamanders and forest-interior birds or those that depend on aquatic systems in their life cycle have been most impacted. Others, such as grassland and early-successional bird species have responded favorably. Some bat species, as an unintended consequence, use legacy deep mines as winter hibernacula in a region with limited karst geology. Recolonization of impacted wildlife often depends on life strategies and species’ vagility, but also on altered or arrested successional processes on the post-surface mine landscape. Many wildlife species will benefit from Forest Reclamation Approach practices going forward. In the future, managers will be faced with decisions about reforestation versus maintaining open habitats depending on the conservation need of species. Lastly, the post-mined landscape currently is the focal point for a regional effort to restore elk (Cervus canadensis) in the Appalachians.
Unique Land Cover Classification to Assess Day-Roost Habitat Selection of Northern Long-Eared Bats on the Coastal Plain of North Carolina, USA
De La Cruz, Jesse L.; True, Michael C.; Taylor, Hila; Brown, Dorothy C.; Ford, W. Mark (2022-05-19)
Reproductively successful and over-wintering populations of the endangered northern longeared bat (Myotis septentrionalis) have recently been discovered on the Coastal Plain of North Carolina. Empirical data on resource selection within the region is limited, likely hindering management of these coastal forests. Our objectives were to determine roosting home range size, selection of day-roost tree species, second- and third-order roosting habitat selection, and to quantify the overall availability of resources in the surrounding landscape. We found core and peripheral roosting home range estimates were large, yet similar to observations from other areas of contiguous forests. Prior to juvenile volancy, female northern long-eared bats appear to select red maple (Acer rubrum), water ash (Fraxinus caroliniana), and loblolly pine (Pinus taeda) as day-roosts, but then use sweetgum (Liquidambar styraciflua), swamp bay (Persea palustris), and water tupelo (Nyssa aquatica) after juvenile volancy. At the second-order spatial scale, roosting home ranges were associated with woody wetlands farther from anthropogenic development and open water. However, within the third-order scale, northern long-eared bats were associated with undeveloped woody wetlands and upland forests, areas containing shorter trees and occurring proximal to open water. Peripheral and core areas were predicted to comprise approximately 20% of the local landscape. Our results show that complex and large tracts of woody wetlands juxtaposed with upland forests in this part of the Coastal Plain may be important for northern long-eared bats locally, results largely consistent with species management efforts in eastern North America.

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