Bats II

Contributed Paper
ROOM: CC, Room 25C
SESSION NUMBER: 82
 

8:10AM White-Nose Syndrome Management and Protection of Critical Habitats Are Both Important for Bat Conservation
Han Li; Kevin A. Parker; Matina C. Kalcounis-Rueppell
Understanding how land cover change will affect species persistence is imperative for guiding conservation efforts. To date White-Nose Syndrome (WNS) in North American has caused regional bat population collapses and extirpations. However, we know little about how these two threats will interact to effect bat distributions into the future. Our aims are to 1) identify land cover preference for two WNS impacted bat species, the tricolored bat (Perimyotis subflavus) and the northern long-eared bat (Myotis septentrionalis), and 2) investigate how future land cover change and spread of WNS will affect these bats’ distributions. We hypothesized that 1) both land cover and WNS affect current bat distribution and 2) WNS will have a larger impact on future bat distribution than land cover. We collected bat distribution data using the standardized North American Bat Monitoring Program stationary survey protocol during 2015, 2016 and 2017 in North Carolina, USA. We used National Land Cover Database data, and current WNS distribution data, as covariates for dynamic occupancy modeling. Bat detections from 161 sites were included to model occupancy probability, local colonization probability, and local extinction probability. We found that land cover was important in explaining occupancy probability, colonization probability, and extinction probability. However, WNS only impacted local extinction probability. Using the models we identified, we predicted future bat distribution in 2035 and 2100 using USGS projected land cover data and predicted future spread of WNS in literature. We found that both WNS and land cover change could significantly alter both species’ distribution. We suggest that even though WNS has an acute impact on bat populations, the management of WNS must go hand in hand with protecting critical habitats because both are important for the conservation of bat species impacted by WNS.
8:30AM Post-Wns Northern Long-Eared Bat Day-Roost Use in the Upper Ohio River and Mid-Atlantic
Jesse De La Cruz; Ryan Ward; Eric Schroder; Sabrina Deeley; Elaine Barr; Samuel Freeze; Nicholas Kalen; Mike Muthersbaugh; Tomas Nocera; W. Mark Ford; Jeremy Sheets
White-nose Syndrome (WNS) impacts have been severe for the northern long-eared bat (Myotis septentrionalis). Although pre-WNS day-roost ecology is well researched, post-WNS information is limited. At present, there appears to be a substantial residual population in the upper Ohio River Valley and along the mid-Atlantic Fall Line, whereas populations in much of the Piedmont and Appalachian Mountains are declining. In 2015-2017, we radio-tagged northern long-eared bats in these areas to determine if day-roost characteristics (tree species, slope position, habitat condition), have changed since WNS. For day-roosts in the Ohio River Valley, 12 species were used, but > 50% occurred in suppressed red maple (Acer rubrum) or sassafras (Sassafras albidum). Similarly, of the 8 species used along the Fall Line, 48% occurred in either suppressed or co-dominant red or sugar maple (Acer saccharum). Non-reproductive groups of northern long-eared bats along the Blue Ridge and Ridge and Valley of the Appalachians used eastern hemlock (Tsuga Canadensis) snags and suppressed red maple almost exclusively. Throughout, most day-roosts (> 75%) were located in cavities. Highly suitable day-roost habitat (≥ 50 year old hardwood forests of 100-200 ha on mid-slopes of western aspects) was uncommon in the Ohio Valley owing to topography and forest age, and similarly was limited along the Fall Line due to urbanization and forest fragmentation. Though largely unoccupied, highly suitable habitat was abundant in the Mountains, owing to prevalent mature forests, variety of slope positions, and public ownership. Where measured, maternity colony “area” of multiple day roosts was smaller than that reported pre-WNS. Based on day-roost selection, our results suggest that the roosting behavior of northern long-eared bats appears unchanged since WNS, and that pre-WNS management efforts for the species still have conservation relevance, at least in the upper Ohio River Valley and mid-Atlantic Fall Line.
8:50AM Managed Forests Provide Roosting Opportunities for Indiana Bats in South-Central Indiana
Scott Bergeson; Joy O’Keefe
There is a growing interest in the effects of timber harvest on forest-dwelling bats due to the potential for timber harvest to reduce available habitat. We conducted a study to determine how endangered Indiana bats (Myotis sodalis) select summer roosts within a Midwestern forest managed for timber. In the summers of 2012–2014, we tracked 4 male and 11 female Indiana bats to 49 roosts (nmale = 24, nfemale = 25) in south-central Indiana, USA. We collected multi-scale data on roosts and associated available trees, randomly located throughout the same landscape. We generated 10 matched pairs conditional logistic regression models based on a priori hypotheses on roost selection and ranked them using Akaike’s Information Criteria. Plausible models explaining female roost selection included those coding for typical Indiana bat maternity roosts and typical tree-cavity bat roosts. Females selected roosts under exfoliating bark on large (17 ± 2 m in height and 34.8 ± 3.0 cm in diameter) standing dead trees and in bat boxes with high solar exposure (28.0 ± 6.0 % canopy closure above roosts). For males, the model coding for predator avoidance was the most plausible explanation of roost selection. Males selected for roosts under exfoliating bark on tall trees (23 ± 2 m; 71% snags) surrounded by snags (4.5 ± 0.7 snags/0.1 ha plot) and live trees (30.4 ± 2.7 live trees/0.1 ha plot). Females roosted in or < 10 m from harvest openings and first-stage shelterwood cuts more than expected (15 of 25 roosts) based on their availability on the landscape. Males roosted in harvest openings as expected (3 of 24 roosts). Our results demonstrate that a managed Midwestern forest provides an array of roosts for Indiana bats and that Indiana bats do not actively avoid roosting near harvest openings in this forest.
9:10AM Estimating Occupancy and Activity of Montana Bat Species Prior to the Arrival of White-Nose Syndrome
Andrea R. Litt; Wilson J. Wright; Emily S. Almberg; Kathryn M. Irvine
The spread of white-nose syndrome (WNS) across the eastern United States has raised conservation concerns for bats and provided motivation for monitoring efforts. Currently, WNS has not yet been detected in any western state besides Washington, and understanding the impacts of WNS on bats in western states requires accurate baseline population assessments and continued monitoring after the disease arrives. Within an occupancy model framework, we analyzed mist netting and acoustic records for eight bat species in Montana to estimate baseline distributions prior to the arrival of WNS. Heterogeneity in occupancy for each species was explained with covariates for forest cover, elevation, ruggedness, and average degree days. Model assessments provided no evidence of residual spatial correlation among occupancy probabilities within each species, but did suggest residual spatial correlation among detection probabilities, likely related to timing of surveys. We incorporated spatially-correlated random effects in the model for detection probabilities to account for these patterns. We created distribution maps from this occupancy model for each species individually and for species combinations of interest. We also developed a model for overall bat activity using additional acoustic data. Even after accounting for nightly weather conditions, patterns in overall activity were highly variable across years and detector locations. For early detection of WNS, surveillance efforts can focus on locations with high estimated probabilities of occupancy for susceptible species and consistent bat activity. We developed tools to visualize estimates from both analyses when selecting locations for WNS surveillance. These estimates of baseline distribution and activity can be used in conjunction and compared to future analyses to better elucidate the impacts of WNS when it arrives in Montana.
9:30AM Atmospheric Mercury as a Method of Sourcing Migratory Tree Bats
Jamin G. Wieringa; Bryan Carstens; Lisle Gibbs
Renewable-energy production from wind turbine facilities has benefits in terms of reducing production of greenhouse gasses but also has negative impacts on wildlife such as increased mortality of tree-roosting bats through turbine strikes. A key question for assessing the management implications of this impact is whether bats that are killed are primarily from local populations or are long-distance migrants. One approach to obtain this information is to use biomarkers that contain location-specific information as a sourcing technique. Here we evaluate the use of mercury present in bat fur to identify source locations of bats killed at wind facilities in the eastern and mid-western US. This is based on the hypothesis that the concentration of mercury in bat fur should be correlated to the variable atmospheric deposition of mercury across North America. To test this idea, we used inductively coupled plasma – mass spectrometry to determine the concentration of mercury in fur from bats captured at known locations, and then compared these levels to publicly available continent-wide baseline maps of atmospheric deposition concentrations. Our results show a small but significant positive relationship between bat fur and atmospheric mercury deposition, suggesting the potential of mercury as a biomarker for sourcing bats killed at wind facilities.

 

Contributed Paper
Location: Cleveland CC Date: October 11, 2018 Time: 8:10 am - 9:50 am