Joshua B. Johnson

Patterns of Acoustical Activity of Bats Prior to and Following White-Nose Syndrome Occurrence

White-nose Syndrome (WNS), a wildlife health concern that has decimated cave-hibernating bat populations in eastern North America since 2006, began affecting source-caves for summer bat populations at Fort Drum, a U.S. Army installation in New York in the winter of 2007–2008. As regional die-offs of bats became evident, and Fort Drum’s known populations began showing declines, we examined whether WNS-induced change in abundance patterns and seasonal timing of bat activity could be quantified using acoustical surveys, 2003–2010, at structurally uncluttered riparian–water habitats (i.e., streams, ponds, and wet meadows). As predicted, we observed significant declines in overall summer activity between pre-WNS and post-WNS years for little brown bats Myotis lucifugus, northern bats M. septentrionalis, and Indiana bats M. sodalis. We did not observe any significant change in activity patterns between preWNS and post-WNS years for big brown bats Eptesicus fuscus, eastern red bats Lasiurus borealis, or the small number of tri-colored bats Perimyotis subflavus. Activity of silver-haired bats Lasionycteris noctivagans increased from pre-WNS to post-WNS years. Activity levels of hoary bats Lasiurus cinereus significantly declined between pre- and post-WNS years. As a nonhibernating, migratory species, hoary bat declines might be correlated with wind-energy development impacts occurring in the same time frame rather than WNS. Intraseason activity patterns also were affected by WNS, though the results were highly variable among species. Little brown bats showed an overall increase in activity from early to late summer pre-WNS, presumably due to detections of newly volant young added to the local population. However, the opposite occurred post-WNS, indicating that reproduction among surviving little brown bats may be declining. Our data suggest that acoustical monitoring during the summer season can provide insights into species’ relative abundance on the landscape as affected by the occurrence of WNS.

Monitoring seasonal bat activity on a coastal barrier island in Maryland, USA

Research on effects of wind turbines on bats has increased dramatically in recent years because of significant numbers of bats killed by rotating wind turbine blades. Whereas most research has focused on the Midwest and inland portions of eastern North America, bat activity and migration on the Atlantic Coast has largely been unexamined. We used three long-term acoustic monitoring stations to determine seasonal bat activity patterns on the Assateague Island National Seashore, a barrier island off the coast of Maryland, from 2005 to 2006. We recorded five species, including eastern red bats (Lasiurus borealis), big brown bats (Eptesicus fuscus), hoary bats (Lasiurus cinereus), tri-colored bats (Perimyotis subflavus), and silver-haired bats (Lasionycteris noctivagans). Seasonal bat activity (number of bat passes recorded) followed a cosine function and gradually increased beginning in April, peaked in August, and declined gradually until cessation in December. Based on autoregressive models, inter-night bat activity was autocorrelated for lags of seven nights or fewer but varied among acoustic monitoring stations. Higher nightly temperatures and lower wind speeds positively affected bat activity. When autoregressive model predictions were fitted to the observed nightly bat pass totals, model residuals >2 standard deviations from the mean existed only during migration periods, indicating that periodic increases in bat activity could not be accounted for by seasonal trends and weather variables alone. Rather, the additional bat passes were attributable to migrating bats. We conclude that bats, specifically eastern red, hoary, and silver-haired bats, use this barrier island during migration and that this phenomenon may have implications for the development of near and offshore wind energy.

Roost Selection by Male Indiana Myotis Following Forest Fires in Central Appalachian Hardwoods Forests

Abstract Despite the potential for prescribed fire and natural wildfire to increase snag abundance in hardwood forests, few studies have investigated effects of fire on bat roosting habitat, partic...

Bat community structure within riparian areas of northwestern Georgia, USA

Abstract. Although it is well known that bats commonly forage in riparian areas, which provide water resources and insect concentrations, the role that the physical structure of riparian areas plays in influencing local bat communities is less certain. In 2000–2002, we used acoustic monitoring to determine bat species presence at 338 riparian sites in northwestern Georgia, USA. We used a 2-dimensional nonmetric multidimensional scaling (NMDS) ordination to assess how separations among species were partially associated with riparian conditions. Our NMDS analysis found some degree of habitat partitioning among bat species occurring in northwestern Georgia and was dictated in part by riparian condition. Myotis grisescens and M. septentrionalis were associated with low-elevation lotic waterways, whereas M. lucifugus, Lasiurus borealis, and Eptesicus fuscus were associated with high-elevation lentic waterways with sparse canopy cover. However, riparian conditions had weak relations with NMDS axes, possibly resulting in coincidental associations in some cases. Regression tree analysis indicated that higher bat species richness was associated with apparently uncommon small, high-elevation waterways with sparse canopy cover as well as larger streams and rivers that had wetlands adjacent to them. Including high-elevation waterways with existing management recommendations for endangered M. grisescens foraging areas (large, low-elevation streams and rivers) will be the most effective conservation strategy to benefit the most bat species in northwestern Georgia and probably elsewhere in the southern Appalachians.

Bats of Assateague Island National Seashore, Maryland

ABSTRACT As significant nocturnal insectivores, bats are an integral part of many ecosystems. Determining bat species composition in an area is a critical first step in managing for this important resource. Little information exists concerning the bat species composition of Marylands Coastal Plain, which is located on the northern periphery of the geographic ranges of five bat species occurring in the southeastern United States. We conducted mist net surveys for bats at Assateague Island National Seashore, a barrier island on Marylands coast, in summer 2005 and summer and autumn 2006. In 2005 we captured 133 bats representing three species, including two big brown bats (Eptesicus fuscus), 129 eastern red bats (Lasiurus borealis) and two purported Seminole bats (L. seminolus). In 2006 we captured 60 eastern red bats in summer and autumn combined. We used Anabat II bat detectors to conduct long-term acoustic monitoring on the island year round and documented three additional bat species, including silver-haired bats (Lasionycteris noctivagans), hoary bats (L. cinereus) and eastern pipistrelles (Pipistrellus subflavus). We documented silver-haired bats during spring and autumn, probably as they were migrating through the area. We used Anabat II bat detectors to conduct short-term monitoring of bat activity at five habitat types during summer 2005 and 2006 and found that total bat activity and eastern red bat activity were similar among forested areas, freshwater pools and bayside marshes. In shrublands, total bat activity and eastern red bat activity was higher than at beach areas, lower than in forested areas and similar at freshwater pools and bayside marshes. The loblolly pine (Pinus taeda) – dominated forests at ASIS provide roosting and foraging habitat mostly for eastern red bats, but also for other migratory bat species.

Forest Succession and Maternity Day Roost Selection by Myotis septentrionalis in a Mesophytic Hardwood Forest

Conservation of summer maternity roosts is considered critical for bat management in North America, yet many aspects of the physical and environmental factors that drive roost selection are poorly understood. We tracked 58 female northern bats (Myotis septentrionalis) to 105 roost trees of 21 species on the Fort Knox military reservation in north-central Kentucky during the summer of 2011. Sassafras (Sassafras albidum) was used as a day roost more than expected based on forest stand-level availability and accounted for 48.6% of all observed day roosts. Using logistic regression and an information theoretic approach, we were unable to reliably differentiate between sassafras and other roost species or between day roosts used during different maternity periods using models representative of individual tree metrics, site metrics, topographic location, or combinations of these factors. For northern bats, we suggest that day-roost selection is not a function of differences between individual tree species per se, but rather of forest successional patterns, stand and tree structure. Present successional trajectories may not provide this particular selected structure again without management intervention, thereby suggesting that resource managers take a relatively long retrospective view to manage current and future forest conditions for bats.

Effects of development of a natural gas well and associated pipeline on the natural and scientific resources of the Fernow Experimental Forest

Development of a natural gas well and pipeline on the Fernow Experimental Forest, WV, raised concerns about the effects on the natural and scientifi c resources of the Fernow, set aside in 1934 for long-term research. A case study approach was used to evaluate effects of the development. This report includes results of monitoring projects as well as observations related to unexpected impacts on the resources of the Fernow. Two points are obvious: that some effects can be predicted and mitigated through cooperation between landowner and energy developer, and that unexpected impacts will occur. These unexpected impacts may be most problematic.

Nocturnal activity patterns of northern myotis ( Myotis septentrionalis ) during the maternity season in West Virginia (USA)

Nocturnal activity patterns of northern myotis (Myotis septentrionalis) at diurnal roost trees remain largely uninvestigated. For example, the influence of reproductive status, weather, and roost tree and surrounding habitat characteristics on timing of emergence, intra-night activity, and entrance at their roost trees is poorly known. We examined nocturnal activity patterns of northern myotis maternity colonies during pregnancy and lactation at diurnal roost trees situated in areas that were and were not subjected to recent prescribed fires at the Fernow Experimental Forest, West Virginia from 2007 to 2009. According to exit counts and acoustic data, northern myotis colony sizes were similar between reproductive periods and roost tree settings. However, intra-night activity patterns differed slightly between reproductive periods and roost trees in burned and non-burned areas. Weather variables poorly explained variation in activity patterns during pregnancy, but precipitation and temperature were negatively associated with activity patterns during lactation.

Effects of acoustic deterrents on foraging bats

Significant bat mortality events associated with wind energy expansion, particularly in the Appalachians, have highlighted the need for development of possible mitigation practices to reduce or prevent strike mortality. Other than increasing turbine cut-in speed, acoustic deterrents probably hold the greatest promise for reducing bat mortality. However, acoustic deterrent effectiveness and practicality has not been experimentally examined and is limited to site-specific case studies. Accordingly, we used a crossover experimental design with prior control period to show that bat activity was reduced 17.1 percent by the deployment of ultrasonic deterrents placed around gauged watershed weir ponds on the Fernow Experimental Forest in West Virginia. We caution that while our results should not be extrapolated to the scope of a typical wind energy production facility, the results warrant further research on the use of acoustic deterrents to reduce bat fatalities.

Food Habits of Myotis leibii during Fall Swarming in West Virginia

Abstract The ecology of Myotis leibii (eastern small-footed myotis) remains largely unclear, including its foraging behavior. During fall, cavernicolous bats must accumulate enough fat reserves to sustain them during winter hibernation. We examined the food habits of eastern small-footed myotis captured at abandoned coal mines at New River Gorge National River in West Virginia during fall 2005. Based on fecal samples from 44 bats, we found that eastern small-footed myotis diets were diverse, containing 9 families within 7 orders of insects. Lepidoptera were consumed by all but one bat and represented the largest average percent volume among insect orders. This study elucidates an important component of the foraging ecology of this rare bat species.