Browsing by Author "Nocera, Tomas"
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- Assessing the Long-term Impacts of White-nose Syndrome on Bat Communities Using Acoustic Surveys at Fort Drum Military InstallationNocera, Tomas (Virginia Tech, 2018-06-12)With declines in abundance and changing distribution of White-nose Syndrome (WNS)-affected bat species, increased reliance on acoustic monitoring is now the new "normal". As such, the ability to accurately identify individual bat species with acoustic identification programs has become increasingly important. Additionally, how bat distribution and habitat associations have changed at the local to sub-landscape scale in the post WNS environment is important to understand. The significance of these changes, relative to bat activity, may be based on the species-specific susceptibility to WNS. We used data collected from Fort Drum Military Installation, New York from the summers of 2003-2017 to analyze the accuracy of acoustic software programs, and assess the changes in relative bat activity, occupancy, and distribution induced by WNS. Our results indicate that continued acoustic monitoring of bat species, such as the little brown bat (Myotis lucifugus) in the Northeast, to assess ongoing temporal and spatial changes, habitat associations, and as a guide to direct future mist-netting should rely more on relative activity as the metric of choice. Furthermore, the continuous spread of WNS across North America will have strong negative effects on bat populations and communities, this study points to how individual species (both impacted and non-impacted) will respond to WNS. We believe that our results can help users choose automated software and MLE thresholds more appropriate for their needs to accurately address potential changes in communities of bat species due to impacts of WNS or other factors.
- Bat activity patterns relative to temporal and weather effects in a temperate coastal environmentGorman, Katherine M.; Barr, Elaine L.; Ries, Lindsay; Nocera, Tomas; Ford, W. Mark (2021-10)The northeastern and mid-Atlantic coasts of the United States are important summer maternity habitat and seasonal migratory corridors for many species of bats. Additionally, the effects of weather on bat activity are relatively unknown beyond coarse nightly scales. Using acoustic detectors, we assessed nightly and hourly activity patterns for eight species of bats over 21 consecutive months at Fire Island National Seashore, New York. The site is an important bat conservation area because it hosts one of the few confirmed northern long-eared bat (Myotis septentrionalis) maternity colonies in the region despite their widespread extirpation due to white-nose syndrome (WNS). There have been no reported captures of little brown bats (M. lucifugus), Indiana bats (M. sodalis), or tri-colored bats (Perimyotis subflavus) at the site post-WNS. Overall, we found mean hourly temperature, time since sunset, day of year, and year to be the most important predictors of bat activity levels for all examined species. Most non-hibernating, migratory species in our study demonstrated a positive relationship to mean temperature at the hourly timescale, whereas cave-hibernating bats tended to show a negative relationship to mean temperature during the time of year when they are expected to be active. Although most bat activity occurred in the late spring through early autumn, peaking in summer, some activity occurred periodically in the winter months, mostly attributable to the big brown bat (Eptesicus fuscus) and silver-haired bat (Lasionycteris noctivigans) phonic group. Unexpectedly, relationships of bat activity to wind and precipitation were largely equivocal. Initial presence (as early as March 30) and departure (between November 1-4) for northern long-eared bats at our study area occurred earlier in the spring and later in the fall than occurs for inland populations, suggesting that the species overwinters on Long Island rather than at inland karst caves or mines. A peak in spring activity characteristic of migratory behavior in the central Appalachians and Atlantic Coast was not observed at Fire Island, although Eastern red bats (Lasiurus borealis) and hoary bats (L. cinereus) - both migratory species - did show a notable rise in activity in the late summer and early fall, suggesting these populations may migrate to and from Fire Island. Understanding the temporal and weather relationships to bat activity in this coastal environment may have important implications for tailoring more effective conservation and management strategies by identifying optimal timing for surveys, tracking bats during peak migratory windows, and providing insights that minimizes impacts to extant bats from activities such as wind-energy development or land management, i.e., forestry.
- Characteristics of Day-roosts Used by Northern Long-Eared Bats (Myotis septentrionalis) in Coastal New YorkGorman, Katherine M.; Barr, Elaine L.; Nocera, Tomas; Ford, W. Mark (Eagle Hill Institute, 2022-05)In North America, Myotis septentrionalis (Northern Long-eared Bat) has experienced precipitous declines from white-nose syndrome. As these bats become rare and difficult to capture, additional day-roost assessments to inform management may fill gaps in our understanding, particularly in habitats and regions where such roosts have never been surveyed. Over 2 summers, we radio-tracked 16 individuals from a maternity colony on Long Island, NY, in a small forested patch surrounded by development and ocean. These bats disproportionately selected small, suppressed Robinia pseudoacacia (Black Locust) trees or snags for roosting. Generally, roosts occurred within the interior or edges of this forest patch, rather than surrounding suburbia, reinforcing the hypothesis that Northern Long-eared Bats are forest adapted. Our study shows even small tracts of forest in coastal, urban areas may have conservation value in providing day-roost and foraging habitat.
- Landowners and the Conservation Reserve Program: Understanding needs and motivations to cultivate participation, retention, and ongoing stewardship behaviorBarnes, Jessica C.; Dayer, Ashley A.; Sketch, Mary; Gramza, Ashley R.; Nocera, Tomas; Steinmetz, Ally; Sorice, Michael G. (Virginia Tech, 2019-03-07)
- Let's Agree to Disagree: Comparing Auto-Acoustic Identification Programs for Northeastern BatsNocera, Tomas; Ford, W. Mark; Silvis, Alexander; Dobony, Christopher A. (2019-12)With the declines in abundance and changing distribution of white-nose syndrome-affected bat species, increased reliance on acoustic monitoring is now the new "normal." As such, the ability to accurately identify individual bat species with acoustic identification programs has become increasingly important. We assessed rates of disagreement between the three U.S. Fish and Wildlife Service-approved acoustic identification software programs (Kaleidoscope Pro 4.2.0, Echoclass 3.1, and Bat Call Identification 2.7d) and manual visual identification using acoustic data collected during summers from 2003 to 2017 at Fort Drum, New York. We assessed the percentage of agreement between programs through pairwise comparisons on a total nightly count level, individual file level (e.g., individual echolocation pass call file), and grouped maximum likelihood estimate level (e.g., probability values that a species is misclassified as present when in fact it is absent) using preplanned contrasts, Akaike Information Criterion, and annual confusion matrices. Interprogram agreement on an individual file level was low, as measured by Cohen's Kappa (0.2-0.6). However, site-night level pairwise comparative analysis indicated that program agreement was higher (40-90%) using single season occupancy metrics. In comparing analytical outcomes of our different datasets (i.e., how comparable programs and visual identification are regarding the relationship between environmental conditions and bat activity), we determined high levels of congruency in the relative rankings of the model as well as the relative level of support for each individual model. This indicated that among individual software packages, when analyzing bat calls, there was consistent ecological inference beyond the file-by-file level at the scales used by managers. Depending on objectives, we believe our results can help users choose automated software and maximum likelihood estimate thresholds more appropriate for their needs and allow for better cross-comparison of studies using different automated acoustic software.
- Patterns of acoustical activity of bats prior to and 10 years after WNS on Fort Drum Army Installation, New YorkNocera, Tomas; Ford, W. Mark; Silvis, Alexander; Dobony, Christopher A. (2019-04)Previous acoustic surveys, netting, and count data have shown that overall bat activity patterns have shifted among most species between pre- and post-white-nose syndrome (WNS) years in much of North America where WNS has occurred. However, the significance of these changes is based on the species-specific susceptibility to WNS. We used acoustically recorded echolocation passes obtained at Fort Drum, New York to describe changes in bat activity pre-WNS (2004-2007) to post-WNS (2008-2018). We examined seasonal and yearly changes in bat activity as they relate to the presence of WNS at hibernacula near (<25 km) Fort Drum. A priori, we expected that overall activity for communal hibernating species would be less in years following WNS, and migratory bats or those hibernating bats that are less affected by WNS would show no response or a positive response, due to niche relaxation/competitive release. Our results indicated both an overall and seasonal decrease in activity for Myotis spp. post-WNS. For WNS-susceptible species, our results reflect the high level of mortality in regional winter hibernacula post-WNS and possibly variable reproductive effort and recruitment thereafter. Although migratory bats did show increases in post-WNS activity throughout the summer, we found little evidence that community displacement was occurring on a nightly level by any species. The continuous spread of WNS across North America has had strong negative effects on bat populations of affected species, and our research identifies how individual species (both impacted and non-impacted) respond to WNS. Published by Elsevier B.V.
- Temporal and spatial changes in Myotis lucifugus acoustic activity before and after white-nose syndrome on Fort Drum Army Installation, New York, USANocera, Tomas; Ford, W. Mark; Dobony, Christopher A.; Silvis, Alexander (2020-06)Changes to hat distribution and habitat associations at the local to sub-landscape scale in the post white-nose syndrome (WNS) environment have received little attention to date despite being critical information for managers. To better understand the spatial nature of hat population declines, we modelled both activity patterns and occupancy from acoustic surveys for the Myotis lucifugus (little brown hat) on Fort Drum Military Installation in New York, USA over 15 summers (2003-2017) that span the pre-WNS, WNS-advent (2008) and post-WNS periods, using a set of generalized linear mixed models and geospatial analysis. Our best supported model indicated significant differences between years with significant declines in activity post-WNS. M. lucifugus activity was most closely associated with woody wetland habitats over the study period, however, the spatial patterns of high activity areas were variable over years, with the areal extent of these high activity areas decreasing post-WNS. Our best supported occupancy model varied by year. However, the null occupancy model [Psi(.)] was either competing (within 2 Delta AIC units) or was the best supported model. Meaning that none of our environmental variables seemed to impact occupancy, and when they did, these differences were not significant. There was high disagreement between our relative activity models and predictions compared to our occupancy models, suggesting that geographic spatial scale and the resolution of the data impacts model outcome. Our results indicate that continued acoustic monitoring of hat species in the Northeast to assess ongoing temporal and spatial changes in habitat associations and to provide direction for future mist-netting studies should rely more on relative activity as the metric of choice rather than site occupancy.