Mid-Atlantic Big Brown and Eastern Red Bats: Relationships between Acoustic Activity and Reproductive Phenology.

Acoustic data are often used to describe bat activity, including habitat use within the summer reproductive period. These data inform management activities that potentially impact bats, currently a taxa of high conservation concern. To understand the relationship between acoustic and reproductive timing, we sampled big brown bats (Eptesicus fuscus) and eastern red bats (Lasiurus borealis) on 482 mist-netting and 35,410 passive acoustic sampling nights within the District of Columbia, Maryland, Pennsylvania, Virginia, and West Virginia, 2015-2018. We documented the proportion of female, pregnant, lactating, and juvenile big brown and eastern red bats within each mist-net sampling event and calculated locally estimated non-parametric scatterplot smoothing (LOESS) lines for each reproductive and acoustic dataset. We compared the peak in acoustic activity with the peaks of each reproductive condition. We determined that the highest levels of acoustic activity within the maternity season were most associated with the period wherein we captured the highest proportions of lactating bats, not juvenile bats, as often assumed.

Spatial factors of white-tailed deer herbivory assessment in the central Appalachian Mountains.

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.

Roosting and foraging social structure of the endangered Indiana bat (Myotis sodalis).

Social dynamics are an important but poorly understood aspect of bat ecology. Herein we use a combination of graph theoretic and spatial approaches to describe the roost and social network characteristics and foraging associations of an Indiana bat (Myotis sodalis) maternity colony in an agricultural landscape in Ohio, USA. We tracked 46 bats to 50 roosts (423 total relocations) and collected 2,306 foraging locations for 40 bats during the summers of 2009 and 2010. We found the colony roosting network was highly centralized in both years and that roost and social networks differed significantly from random networks. Roost and social network structure also differed substantially between years. Social network structure appeared to be unrelated to segregation of roosts between age classes. For bats whose individual foraging ranges were calculated, many shared foraging space with at least one other bat. Compared across all possible bat dyads, 47% and 43% of the dyads showed more than expected overlap of foraging areas in 2009 and 2010 respectively. Colony roosting area differed between years, but the roosting area centroid shifted only 332 m. In contrast, whole colony foraging area use was similar between years. Random roost removal simulations suggest that Indiana bat colonies may be robust to loss of a limited number of roosts but may respond differently from year to year. Our study emphasizes the utility of graphic theoretic and spatial approaches for examining the sociality and roosting behavior of bats. Detailed knowledge of the relationships between social and spatial aspects of bat ecology could greatly increase conservation effectiveness by allowing more structured approaches to roost and habitat retention for tree-roosting, socially-aggregating bat species.