Winter Roosting by Eastern Red Bats in Ozark Mountain Forests of Missouri

The eastern red bat (Lasiurus borealis Müller, 1776) is a widespread species that roosts in evergreen or dead foliage suspended in trees during winter but retreats to leaf litter during colder periods. Roosting in leaf litter by eastern red bats makes them vulnerable to prescribed fires in winter. Using radio telemetry, we tracked 33 male eastern red bats to 101 winter (November–February) roosts and quantified roost locations, habitat surrounding roosts, and landscape attributes of roost locations. When roosting in trees, bats preferred oaks but generally avoided other tree species; they used pines in proportion to their availability. During colder periods, bats retreated to roosts in leaf litter where 21% suffered mortality either from predation/scavenging or unknown causes while roosting on the ground. Models of roost selection indicated that southerly aspect was the most important factor determining roost selection, and both tree- and leaf-litter roosts were predominately (≥94%) on upper south-facing slopes. Prescribed burning in late morning/early afternoon on clear days when temperatures under leaf litter are warmest in winter could reduce potential mortality by allowing faster arousal time for hibernating bats.

Timing and Weather Offer Alternative Mitigation Strategies for Lowering Bat Mortality at Wind Energy Facilities in Ontario

Relatively high mortality of migratory bats at wind energy facilities has prompted research to understand the underlying spatial and temporal factors, with the goal of developing more effective mitigation approaches. We examined acoustic recordings of echolocation calls at 12 sites and post-construction carcass survey data collected at 10 wind energy facilities in Ontario, Canada, to quantify the degree to which timing and regional-scale weather predict bat activity and mortality. Rain and low temperatures consistently predicted low mortality and activity of big brown bats (Eptesicus fuscus) and three species of migratory tree bats: hoary bat (Lasiurus cinereus), eastern red bat (L. borealis), and silver-haired bat (Lasionycteris noctivagans). Bat activity occurred in waves with distinct peaks through the season; regardless of seasonal timing, most activities occurred in the first half of the night. We conclude that wind energy facilities could adopt a novel and more effective curtailment strategy based on weather and seasonal and nocturnal timing that would minimize mortality risks for bats while increasing the opportunities for power generation, relative to the mitigation strategy of increasing cut-in wind speed to 5.5 m/s.

Eastern Red Bat Responses to Fire during Winter Torpor

Prescribed fires are a forest management tool used to improve natural areas for a variety of benefits including increased plant diversity, reduced competition for desired species, decreased fuel loads, and improved wildlife habitat. The post-fire results in landscapes have shown positive benefits for bat populations. However, prescribed fires set in the winter may cause direct mortality of eastern red bat (Lasiurus borealis) populations that use leaf litter for roosting during periods of colder (<10 °C) temperatures. Therefore, we used controlled laboratory techniques to explore if eastern red bats arouse from torpor when exposed to cues associated with fire (i.e., smoke and the sound of fire). Through subsequent field trials, we confirmed latencies of first response (i.e., movement or increased respiration), arousal, and flight behaviors to the stimuli of fire. We provide evidence of smoke influencing eastern red bat first response and arousal through laboratory and field trial results. Latencies of all behaviors were negatively correlated with temperatures and wind speeds prior to and during field trials. We recommend prescribing winter fires on days when temperatures are >10 °C to provide eastern red bats with a better chance to passively rewarm and react to an approaching fire.

Winter roost selection of Lasiurine tree bats in a pyric landscape

Day-roost selection by Lasiurine tree bats during winter and their response to dormant season fires is unknown in the southeastern United States where dormant season burning is widely applied. Although fires historically were predominantly growing season, they now occur in the dormant season in this part of the Coastal Plain to support a myriad of stewardship activities, including habitat management for game species. To examine the response of bats to landscape condition and the application of prescribed fire, in the winter of 2019, we mist-netted and affixed radio-transmitters to 16 Lasiurine bats, primarily Seminole bats (Lasiurus seminolus) at Camp Blanding Joint Training Center in northern Florida. We then located day-roost sites to describe roost attributes. For five Seminole bats, one eastern red bat (Lasiurus borealis), and one hoary bat (Lasiurus cinereus), we applied prescribed burns in the roost area to observe bat response in real-time. Generally, Seminole bats selected day-roosts in mesic forest stands with high mean fire return intervals. At the roost tree scale, Seminole day-roosts tended to be larger, taller and in higher canopy dominance classes than surrounding trees. Seminole bats roosted in longleaf (Pinus palustris), slash (Pinus elliotii) and loblolly pine (Pinus taeda) more than expected based on availability, whereas sweetbay (Magnolia virginiana), water oak (Quercus nigra) and turkey oak (Quercus laevis), were roosted in less than expected based on availability. Of the seven roosts subjected to prescribed burns, only one male Seminole bat and one male eastern red bat evacuated during or immediately following burning. In both cases, these bats had day-roosted at heights lower than the majority of other day-roosts observed during our study. Our results suggest Seminole bats choose winter day-roosts that both maximize solar exposure and minimize risks associated with fire. Nonetheless, because selected day-roosts largely were fire-dependent or tolerant tree species, application of fire does need to periodically occur to promote recruitment and retention of suitable roost sites.

Sympatric Bat Species Prey Opportunistically on a Major Moth Pest of Pecans

Native predators provide undervalued pest suppression services to agriculture. Studies of pest consumption by insectivorous bats tend to focus upon single species in large, centralized colonies, while bats dispersed in small groups within the agricultural matrix often go unnoticed. Pecan trees, Carya illinoinensis, and the destructive pecan nut casebearer (PNC) moth, Acrobasis nuxvorella, comprise a tightly linked host–parasite system in a widespread agroecosystem native to North America. Here we use a quantitative polymerase chain reaction (qPCR) assay of fecal DNA to document predation on PNC moths by an assemblage of sympatric bat species across episodic peaks in PNC abundance. Although five species of bats consume PNC moths, greater predation by a solitary tree-roosting bat (eastern red bat, Lasiurus borealis) than other species is suggested by a higher frequency of PNC occurrence and quantity of PNC gene copies in fecal samples. Consumption of PNC by bats during all documented peaks in moth activity suggests that predation pressure occurs throughout the PNC season. Our results highlight the need to consider multi-species assemblages and different foraging strategies when assessing pest suppression services, particularly in agroforestry or tree crops. Assessing the diet of only common or easily captured species limits our ability to accurately document pest consumption by bats.

Increasing evidence that bats actively forage at wind turbines

Although the ultimate causes of high bat fatalities at wind farms are not well understood, several lines of evidence suggest that bats are attracted to wind turbines. One hypothesis is that bats would be attracted to turbines as a foraging resource if the insects that bats prey upon are commonly present on and around the turbine towers. To investigate the role that foraging activity may play in bat fatalities, we conducted a series of surveys at a wind farm in the southern Great Plains of the US from 2011–2016. From acoustic monitoring we recorded foraging activity, including feeding buzzes indicative of prey capture, in the immediate vicinity of turbine towers from all six bat species known to be present at this site. From insect surveys we found Lepidoptera, Coleoptera, and Orthoptera in consistently high proportions over several years suggesting that food resources for bats were consistently available at wind turbines. We used DNA barcoding techniques to assess bat diet composition of (1) stomach contents from 47 eastern red bat (Lasiurus borealis) and 24 hoary bat (Lasiurus cinereus) carcasses collected in fatality searches, and (2) fecal pellets from 23 eastern red bats that were found on turbine towers, transformers, and tower doors. We found that the majority of the eastern red bat and hoary bat stomachs, the two bat species most commonly found in fatality searches at this site, were full or partially full, indicating that the bats were likely killed while foraging. Although Lepidoptera and Orthoptera dominated the diets of these two bat species, both consumed a range of prey items with individual bats having from one to six insect species in their stomachs at the time of death. The prey items identified from eastern red bat fecal pellets showed similar results. A comparison of the turbine insect community to the diet analysis results revealed that the most abundant insects at wind turbines, including terrestrial insects such as crickets and several important crop pests, were also commonly eaten by eastern red and hoary bats. Collectively, these findings suggest that bats are actively foraging around wind turbines and that measures to minimize bat fatalities should be broadly implemented at wind facilities.

Multi-scale factors related to abundance of bats and insect prey in savannas, woodlands, and forests in the Ozark Highlands, USA

Restoration of savanna and woodland ecosystems are high priorities for state and federal agencies in the Midwest and prescribed fire and mechanical tree thinning are the main tools used to restore these communities. Information on how bat species and their insect prey respond to restoration is needed to guide management decisions for species of conservation concern. There is a heightened urgency to collect demographic data during the 07 maternity season due to white-nose syndrome (WNS) and other threats to bat populations. Our objectives were to: 1) evaluate the performance of the n-mixture model for repeated count data and the general multinomial Poisson model for removal sampling (n-mixture model and removal model, respectively) for estimating bat abundance from simulated mist-net capture data, 2) determine the relationships between prescribed fire, vegetation structure, and site characteristics on insect abundance, and 3) determine the effect of restoration, vegetation structure, and landscape factors on bat species abundances across a gradient of savannas, woodlands, and non-managed forest in the Ozark Highlands of Missouri. We fit the n-mixture and removal models in the UNMARKED package in R, and simulated datasets that examined how both models would perform based on potential study design constraints, various probabilities of detection, and population sizes. We simulated 4 scenarios each based on 85 iterations on 1000 randomly generated datasets. We calculated relative bias (RB), mean absolute error (MAE), and mean absolute percent error (MA%E) from model predictions to evaluate model performance. Relative bias, MAE, and MA%E decreased as detection probability and bat abundance increased. Model fit was acceptably low when bat abundance was greater than 70, and detection probability was greater than 0.5 for n-mixture models. The removal model outperformed the n-mixture model in all scenarios except when detection probability was 0.05. The removal model correctly estimated bat abundance for 50 percent of simulated scenarios versus the n-mixture model's 3 out of 43. Utilization of the removal model using data from repeated mist-net surveys may allow resource managers and conservationists to better quantify how resource management and landscape composition affect bat species abundance and overall populations. We provide managers with evidence of the utility of the removal model to estimate bat abundances from repeated mist-net survey data while incorporating meaningful habitat, management, and landscape covariates. Furthermore, documenting changes in populations sizes during the 07 maternity season will enable improved conservation practices for species management. We sampled insects at 8 plots in 2014, and 4 plots in 2015 and 2016 within 250 m of each mist-net sites. We fit generalized linear mixed effects models to evaluate a priori hypotheses on the effects of savanna woodland restoration on insect abundances. Prescribed fire did affect insect abundances at plots surrounding each mist-net site. Insect plots burned 2 or 3 times within the last ten years had higher insect abundances for some insect response groups compared to non-managed plot. Year since a plot burned also affected insect abundances, with sites burned more recently within 3 years had lower insect abundances for some insect response groups and in others -- we found no relationship. We only evaluated insect Orders and did not examine specific families or species richness to understand how management affects diversity of insects. Temperature was the best predictor of insect abundances at plots for most response variables, and we found support for site aspect, and tree density by size classes. Managers should be mindful that different insect groups had different responses to prescribed fire, therefore a diversity of practices in the landscape will provide for more diverse insect prey Overall, restoration practices did not have a lasting negative effect on insect abundances, and some positive effects. We conducted mist-net surveys at 89 sites across the Ozark region of Missouri from 2014-2016, and collected demographic data on 4 bat species captured: northern longeared bat (Myotis septentrionalis), tri-colored bat (Perimyotis subflavus), evening bat (Nycticeius humeralis), and eastern red bat (Lasiurus borealis). We fit the removal model to evaluate multi-scale a priori hypotheses on the effects of restoration, landscape factors, and prey availability at sites that potentially affect either the detection or abundance of bats at sites. Top models for all four bat species highlighted the importance of evaluating multiple spatial scales in ecological studies. Overall, we found no evidence that restoration negatively affected any of the bat species investigated; although, northern long-eared bats abundance presented stronger positive relationship to percent forest and increased tree densities than to percent savanna-woodlands within 1km. Our study was the first to predict abundances from repeated count data from mist-net surveys during the 07 maternity season and accounting for varying detection probabilities. We did not find support for relationships between potential insect prey and bat abundances. Eastern red bats, tricolored, and evening bat abundances were positively related to prescribed fire and negatively to tree densities or percent canopy and therefore should respond positively to savanna and woodland restoration. Northern long-eared bat had higher abundances at sites with higher tree densities of pole and saw timber and eastern red bat and northern long-eared bat abundances was positively related to sites with higher percentage of forest and savanna-woodland habitat within 1 km of mist-net sites. Evening bat abundances was the greatest at sites that had higher fire frequencies within 1 km of a mist-net site. We suggest managers consider the tradeoffs among species in these abundance relationships when planning management and that restoration of savanna and woodlands, when part of a larger management goal to create heterogeneity of forest types, will likely promote higher abundances of all four bat species.