Detection of bats by mist-nets and ultrasonic detectors

Bats are under threat from habitat loss, energy development, and the disease white-nose syndrome. The North American Bat Monitoring Program (NABat) suggests standardized, large scale monitoring to benefit ecologists and managers. Our first objective was to determine the efficacy of NABat in South Carolina. Detection probabilities differ within and among species and among survey conditions. Thus, our second objective was to determine factors affecting detection probabilities. Finally, effective management strategies addressing large scale threats require landscape scale analyses. Thus, our third objective was to conduct state-wide assessments of environmental factors influencing landscape occupancy and generate predicted distributions. We conducted NABat acoustic surveys across South Carolina from mid-May through July 2015 and 2016. To determine the efficacy of NABat, we compared species detections to known distributions based on historical records, and to predicted distributions based on environmental occupancy models. We detected some species throughout their ranges and others in ≤ 50% of cells within their ranges, and detected some species outside their ranges. Thus, NABat monitoring may be suitable for many species but may not be suitable for species with echolocation calls that are difficult to detect or identify, and may also reveal new information about species distributions. To determine factors that affected detection, we evaluated support for detection models. We found that detection covariates greatly varied among species, but most species had higher detection probabilities at stationary points than mobile transects. Our results suggested that effects of factors on detection probabilities were based on biological and behavioral characteristics of species, which indicated the importance of monitoring survey variables and accounting for them in analyses. To assess effects of environmental factors on occupancy, we evaluated temporally dynamic occupancy models. Occupancy probability differed among ecoregions for northern yellow bats (Dasypterus intermedius) and Myotis species. Hoary bats (Lasiurus cinereus) were negatively associated with forest edge density. We found no significant effects of habitat conditions for five species. Thus, for some species, site-use analyses of NABat data may be more appropriate than grid-based occupancy analyses. However, predicted distributions closely matched species habitat associations. Our findings can improve future monitoring efforts and inform conservation priorities.

2009

Journal of Mammalogy, 1999

To evaluate the efficacy of the Anabat II ultrasonic detector and analysis system for use as a tool for conducting inventories, we compared results of acoustic versus capture techniques in the southwestern United States. We sampled 57 locations using standard methods (mist nets and double-frame harp traps) and simultaneously with an ultrasonic detector (Anabat II). Assuming total number of species obtained by both methods equaled a complete inventory, captures accounted for 63.5% and acoustic sampling 86.9% of the combined species present. Acoustic sampling was capable of sampling bats that routinely flew outside the sampling capabilities of nets and traps. We found no statistical difference between capture and acoustic sampling with respect to species that use low-intensity echolocation. Acoustic sampling of bat communities is a powerful tool but should be used with various capture techniques to perform the most accurate inventory.

2014

Acoustic surveys with echolocation detectors have become a common method for monitoring bats worldwide. In the eastern United States, the spread of white-nose syndrome and the threat it poses for many bat species, particularly endangered species such as the Indiana bat (Myotis sodalis), has increased the need to monitor bat populations. Two popular methods, stationary and mobile surveys, are currently used by agencies in the United States to inform management and conservation efforts and by researchers to monitor and study bat populations. Despite the widespread use of these methods, no study has compared the efficiency in echolocation ‘capture’ success relative to human-hour of effort of these two methods. To compare these techniques we collected acoustic data with Anabat detectors in state forests of southern Indiana using stationary and mobile surveys in the way they are typically implemented. We compared the efficiency of each method at recording identifiable call files and Myot...

Northern Journal of Applied Forestry, 2004

We used Anabat acoustical monitoring devices to examine bat activity in intact canopy forests, complex canopy forests with gaps, forests subjected to diameter-limit harvests, recent deferment harvests, clearcuts and unmanaged forested riparian areas in the Allegheny Mountains of West Virginia in the summer of 1999. We detected eight species of bats, including the endangered Indiana bat (Myotis sodalis). Most bat activity was concentrated in forested riparian areas. Among upland habitats, activity of silver-haired bats (Lasionycteris noctivagans) and hoary bats (Lasiurus cinereus) was higher in open, less cluttered vegetative types such as recent deferment harvests and clearcuts. Our results suggest that bat species in the central Appalachians partially segregate themselves among vegetative conditions based on differences in body morphology and echolocation call characteristics. From the standpoint of conserving bat foraging habitat for the maximum number of species in the central Ap...

Biological Conservation, 2005

Journal of the Pennsylvania Academy of Science

To maximize efficiency in assessing the composition and relative activity of summer bat communities, we quantitatively compared differences in the amount and quality of data collected using the AnaBat echolocation detection system and double-or triple-stacked mist netting efforts. In summer 2009, we surveyed bats at 27 sites in Pennsylvania and New Jersey, monitoring from sunset until5-h post-sunset over the period of one or two nights. We recorded 5,594 echolocation call sequences in which we identified seven species (Eptesicus fuscus, lAsionyc- teris noctivagans, lAsiurus borealis, lAsiurus cinereus, Myotis lucifugus, M. septentrionalis, and M. sodalis). All of these species except for Myotis sodalis (Indiana bat) also were captured in mist nets (N = 160 individual captured). We found no difference between the total number of echolocation call sequences on the first night versus the average number of calls across both nights, indicating that relative activity of bats could be attained in just one night of AnaBat recordings. However, if the goal is to assess species richness or detection of a particular species, we found that two survey nights were necessary for both acoustic and mist netting techniques. More importantly, AnaBat recordings showed that detection of the endangered Indiana bat is significantly more likely when surveys extend over two nights. Overall, the AnaBat system is more likely to detect more species, assuming species identification techniques are reliable. Mist netting provides vital information about individual health (especially important in light of White-nose Syndrome) and life history traits and can absolutely verify the presence of a target species. Our research can serve as a guide to effectively plan bat surveys for assessing the species richness and relative activity across sites for bat communities.

2005

We used Anabat acoustical monitoring devices to examine bat activity in intact canopy forests, complex canopy forests with gaps, forests subjected to diameter-limit harvests, recent deferment harvests, clearcuts and unmanaged forested riparian areas in the Allegheny Mountains of West Virginia in the summer of 1999. We detected eight species of bats, including the endangered Indiana bat (Myotis sodalis). Mast bat activity was concentrated in forested riparian areas. Among upland habitats, activity of silver-haired bats (Lasionycteris noctivagans) and hoary bats (Lasiurus cinereus) was higher in open, less cluttered vegetative types such as recent deferment harvests and clearcuts. Our results suggest that bat species in the central Appalachians partially segregate themselves among vegetative conditions based on drfferences in body morphology and echolocation call characteristics. From the standpoint of conserving bat foraging habitat for the m i m u m number of species in the central ...