Bats In Areas Research Articles

Risk Assessment of Radon Exposure by Ingestion and Inhalation of Groundwater Within Different Age Groups

AbstractRadon and its short‐lived progeny are exposed to most human exposures as a natural source of radiation. Many studies have presumed that one of the most common incidences of lung cancer, colon cancer, and stomach cancer is caused by radon‐contaminated water. In this study, water was collected from different groundwater sources in the Hafr Al Batin area, Saudi Arabia, and the radon concentration was investigated using an electronic portable radon detector. The annual effective dose of radon exposure by ingestion and inhalation of water is calculated from that radon concentration for the different age groups to assess the risk of radon exposure. The calculated annual effective doses are then compared with the international standard of risk limit as directed by the international organizations. The estimated radon concentration for groundwater samples is found to be between 0.03 and 3.20 Bq/L with an average value of 1.16 Bq/L. These estimated values are below the safety limits set by the USEPA and EAEC and far below those recommended by the UNSCEAR, EC, and WHO standards. The calculated annual effective dose of radon exposure for the different age groups ranging from infant to adult is found to be in the range of 0.05 to 16.24 μSv/year, with a mean value of 5.89 μSv/year, which is in the safe limit recommended by the EC and WHO. The obtained results of this present study will support the authority and regulators who are responsible for controlling and strategizing to ensure public safety against radon exposure.

Informing wind energy development: Land cover and topography predict occupancy for Arizona bats.

Wind energy is a growing source of renewable energy with a 3-fold increase in use globally over the last decade. However, wind turbines cause bat mortality, especially for migratory species. The southwest United States has high bat species diversity and is an important area for migratory species, although little is known about their seasonal distribution. To examine potential risk to bats in areas proposed for wind energy development, we characterized bat occupancy spatially and temporally across northern Arizona, identifying use during summer when bats are reproductively active and fall during the migratory season. Our objectives were to determine occupancy of migratory species and species of greatest conservation need and develop a probability of occupancy map for species to identify areas of potential conflict with wind energy development. We selected 92 sites in 10 clusters with potential for development and used acoustic detectors to sample bats in the summer and fall of 2016 and 2017 for 6 nights per site per year. We predicted response of migratory bat species and species of special concern to 9 landscape variables using Program MARK. During summer, higher densities of forest on the landscape resulted in a higher probability of occupancy of migratory species such as hoary bats (Lasiurus cinereus), silver-haired bats (Lasionycteris noctivagans), big free-tailed bats (Nyctinomops macrotis), and species of conservation need such as spotted bats (Euderma maculatum). During the fall, higher concentration of valleys on the landscape predicted occupancy of hoary bats, big free-tailed bats, and spotted bats. High bat occupancy in the fall was also associated with higher elevation and close proximity to forests. We recommend that wind turbines be placed in open, flat grasslands away from forested landscapes and concentrations of valleys or other topographic variation.

Winter activity of boreal bats

Natural hibernation sites used by bats in areas that lack cave features have long remained unresolved. To investigate hibernation site selection and winter activity of boreal bats, we recorded bat calls using passive acoustic monitoring at 16 sites in South-Western Finland. These sites included four rock outcrops with crevices and cave features, three glacial erratics or boulder fields, three ancient shores, three root cellars and three control sites where we did not expect bats to be overwintering. Our results revealed echolocation calls of Eptesicus nilssonii, Plecotus auritus and Myotis sp. We recorded significantly more activity near rock outcrops compared to other habitats, excluding root cellars. We also found that ambient temperature had a positive effect on bat activity and found evidence that P. auritus may be using low barometric pressure as a proxy for suitable foraging conditions during the winter. Our results suggest that rock outcrops may be more important to bats than previously acknowledged, highlighting the need to take these sites in account in planning of conservation measures. Furthermore, our findings underline the suitability of using acoustic monitoring in homing on hibernation sites that are not otherwise accessible.

Unexpected Diversity in Regenerating Sites Stresses the Importance of Baselines: A Case Study With Bats (Order Chiroptera) on the Osa Peninsula, Costa Rica

Introduction: Background and Research Aims:Assessing biodiversity recovery is key to determine whether the objectives of habitat restoration for conservation are met. Many restoration initiatives use cross-sectional comparisons of wildlife communities to infer restoration impact instead of longitudinal assessments from a baseline state. Using an indicator of biodiversity in the neotropics— bats— we demonstrate how assessing community diversity and composition in an area targeted for restoration prior to implementation, and when compared to surrounding intact forest, provides the groundwork to track changes in the community post-restoration.MethodsWe assessed bat communities by 1) using mist-net surveys to identify species in the family Phyllostomidae (leaf-nosed bats), and 2) conducting acoustic surveys to identify non-phyllostomid species (aerial insectivores).ResultsFor both groups, we found that areas targeted for restoration had similar diversity as the surrounding forest, but the two habitat types differed in community composition. Phyllostomids were captured at higher rates in forest, but aerial insectivores were detected at higher rates in restoration habitat.ConclusionOur baseline assessment revealed unexpected diversity in areas targeted for restoration. The presence of all trophic groups in restoration habitat suggests that bats provide key ecosystem services in the restoration process, such as through seed dispersal, pollination and insect pest control. Implications for Conservation: Conducting a baseline survey of bats in areas targeted for restoration demonstrated that the community was not species poor at the baseline and was different from the surrounding forest, allowing us to better track restoration success and the effects of different restoration treatments.

SUMMER POPULATION OF BATS IN PROTECTED AREAS AND THEIR SURROUNDINGS IN THE EAST OF FENNOSCANDIA

The eastern outskirts of Fennoscandia harbour two protected areas – Vodlozersky and Kenozersky national parks. They are relatively close to each other and occupy vast taiga territories in the Republic of Karelia and the Arkhangelsk Region. They are distinguished for the share of old-growth forests and the pattern of agricultural use of the land. The species composition of bats in these protected areas has not been previously studied, and the only species definitely known to inhabit the territories was the Northern bat. Special censuses of bats in these areas were carried out using traditional (mist nets, visual observations) and modern (static ultrasonic detector) methods. The counts were carried out at fixed points, along car and water transects. A total of 28 bats of 4 species were captured (Northern bat Eptesicus nilssonii Keyserling & Blasius 1839, Daubenton’s bat Myotis daubentonii Kuhl 1817, Brandt’s bat M. brandtii Eversmann 1845, whiskered bat M. mystacinus Kuhl 1817), and records were made of 185 bats of 7 species (apart from the ones listed above they were the brown long-eared bat Plecotus auritus L. 1758, common noctule Nyctalus noctula Schreber 1774, parti-coloured bat Vespertilio murinus L. 1758, pond bat M. dasycneme Boie 1825, Natterer’s bat M. nattereri Kuhl 1817), and bats classified as Brandt’s/whiskered bats. The relative abundance (%) and relative density (ind./km of transect) of some species are reported, as well as the dominance of the northern bat in all the communities, which is characteristic of the middle taiga subzone in general. The northernmost summer habitats of the whiskered bat in the European North of Russia were identified. A comparative analysis of the two protected areas in terms of species composition, relative abundance and relative density of bats did not reveal any sharp differences in these parameters.

Bat roosts in Tasmania’s production forest landscapes: importance of mature forest for maternity roosts

Mature forest is a key resource for hollow-using bats, but its importance in shaping where bats roost during breeding is not well understood. This lack of understanding limits the ability of forest managers to make informed decisions on the type, amount and spatial arrangement of mature forest to retain for bats in areas used for timber production. Using radio-telemetry, day roosts of three sympatric hollow-using bat species – the chocolate wattled bat (Chalinolobus morio), the Tasmanian long-eared bat (Nyctophilus sherrini) and the lesser long-eared bat (Nyctophilus geoffroyi) – were located in two forested landscapes in south-eastern Tasmania, Australia. By radio-tracking 24 bats in the maternity season, 76 roosts were located, with interspecific variation in roosting preferences evident at the roost, patch and landscape scale. Maternal colonies showed a clear selection for roosting in areas of the landscape containing the highest availability of mature forest, with smaller patches, strips and individual trees used to a greater extent for roosting in the landscape where mature forest was scarce. These findings showcase the importance of retaining mature forest at multiple spatial scales for hollow-using bats.

Habitat usage of Daubenton's bat (Myotis daubentonii), common pipistrelle (Pipistrellus pipistrellus), and soprano pipistrelle (Pipistrellus pygmaeus) in a North Wales upland river catchment.

Distributions of Daubenton's bat (Myotis daubentonii), common pipistrelle, (Pipistrellus pipistrellus), and soprano pipistrelle (Pipistrellus pygmaeus) were investigated along and altitudinal gradient of the Lledr River, Conwy, North Wales, and presence assessed in relation to the water surface condition, presence/absence of bank‐side trees, and elevation. Ultrasound recordings of bats made on timed transects in summer 1999 were used to quantify habitat usage. All species significantly preferred smooth water sections of the river with trees on either one or both banks; P. pygmaeus also preferred smooth water with no trees. Bats avoided rough and cluttered water areas, as rapids may generate high‐frequency echolocation‐interfering noise and cluttered areas present obstacles to flight. In lower river regions, detections of bats reflected the proportion of suitable habitat available. At higher elevations, sufficient habitat was available; however, bats were likely restricted due to other factors such as a less predictable food source. This study emphasizes the importance of riparian habitat, bank‐side trees, and smooth water as foraging habitat for bats in marginal upland areas until a certain elevation, beyond which bats in these areas likely cease to forage. These small‐scale altitudinal differences in habitat selection should be factored in when designing future bat distribution studies and taken into consideration by conservation planners when reviewing habitat requirements of these species in Welsh river valleys, and elsewhere within the United Kingdom.

A novel method for targeting survey effort to identify new bat roosts using habitat suitability modelling

In the UK, four out of 18 bat species are listed on the EU Habitats Directive, including the lesser horseshoe bat (Rhinolophus hipposideros), and their population status is closely monitored by visiting known roosts. R. hipposideros predominantly form maternity roosts in buildings, but roosts are impermanent features in the landscape and their distribution changes as bats form new roosts and abandon others. Locating new roosts requires intensive surveys which are challenging and inefficient. In this study, we provide a novel model-based strategy to identify potential R. hipposideros maternity roost sites that can be used to monitor bat populations. First, we model potential maternity roost habitat using record centre data on roost locations across Wales, Great Britain. We then constrain the area identified from modelling using record centre data on locations of bats in areas with no known roosts. We used two variable selection methods and three pseudo-absence data sets (random background points, random points in buildings and target group selection of mammal records) to produce six habitat suitability models. The three pseudo-absence data sets produced different habitat suitability maps, demonstrating the influence of pseudo-absence selection on species distribution models. The six models were combined using weighted mean average to produce an ensemble model that performed better than individual models and that indicated high levels of congruence in areas predicted to have high habitat suitability for maternity roosts. Our model revealed an extensive area (6523 km2; 31% of the area of Wales) containing 18,051 buildings in suitable habitat. Using record centre data on bat activity outside commuting range from known roosts reduced the potential survey area to 133 km2 (0.6% of the area of Wales) and 207 buildings. Our modelling outputs can be used to direct volunteers and bat surveyors in more targeted and efficient searches.

Ecology and conservation of insectivorous bats in fragmented areas of macadamia production in eastern Australia

Microbats perform important ecological services in agro-ecosystems, but several species are globally threatened by loss of roosting and breeding habitats. The successful conservation of bats in agricultural land requires adequate knowledge of their ecology. Using ultrasonic recorders, we studied the activity of insectivorous bats in areas of macadamia production in eastern Australia at two spatial scales: across woodland-orchard transects at the local scale and across three levels of fragmentation at the landscape scale. At the local scale, activity patterns of ‘clutter’ and ‘edge’ specialists were consistently higher in woodland patches, gradually decreasing towards isolated orchards, where only a few ‘open’ specialists were active. At the landscape scale, bat community activity was affected by the level of fragmentation, partly because three of the most recorded taxa (Austronomus australis, Saccolaimus flaviventris and Miniopterus australis) had their highest activity in less-fragmented areas. A distance-based model explained 24% of the bat community activity based on a combination of six environmental variables. Canonical correspondence analysis showed that a number of bat taxa were associated with open areas of macadamia, whereas other taxa were associated with increasing values of landscape composition, and arthropod and water availability. In addition, total bat activity was highly correlated with foraging rate. These results suggest that most bat taxa were influenced by proximity to woodland and the degree of fragmentation, and only few taxa were able to exploit isolated orchards. Environmental factors that promote bat activity could be exploited to strengthen conservation efforts. Preserving remnant woodland and promoting habitat heterogeneity will benefit several bat species. In particular, the foraging activity of ‘edge’ specialists could be fostered by increasing landscape connectivity and maintaining unobstructed water bodies near macadamia orchards. Considering that bats forage as they navigate these areas, conservation efforts could also bring benefits to farmers through pest-reduction services.

Effects of clear-fell harvest on bat home range.

We investigated effects of roost loss due to clear-fell harvest on bat home range. The study took place in plantation forest, inhabited by the New Zealand long-tailed bat (Chalinolobus tuberculatus), in which trees are harvested between the ages 26–32 years. We determined home ranges by radiotracking different bats in areas that had and had not been recently clear-fell harvested. Home ranges were smaller in areas that had been harvested. Adult male bats selected 20–25 year old stands within home ranges before and after harvest. Males selected edges with open unplanted areas when harvest had not occurred but no longer selected these at proportions greater than their availability post harvest, probably because they were then readily available. This is the first radiotracking study to demonstrate a change in home range size and selection concomitant with felling of large areas of plantation forest, and thus quantify negative effects of forestry operations on this speciose group. The use of smaller home ranges post-harvest may reflect smaller colony sizes and lower roost availability, both of which may increase isolation of colonies and vulnerability to local extinction.

Characteristics ofLasiurus intermedius(Northern Yellow Bat) Roosts on Sapelo Island, Georgia

We radio-tracked 3 male and 1 female Lasiurus intermedius (Northern Yellow Bat) to 16 unique roosts on Sapelo Island, GA in summer 2010. All bats roosted in Tillandsia usneoides (Spanish Moss) hanging in hardwood trees. Trees used as roosts were similar in height as surrounding trees but were larger in diameter. Mature hardwood stands appear to be important roosting habitats for Northern Yellow Bats in areas where Pinus (pine) and mixed-pine hardwood habitats dominate the landscape.

Range overlap and association patterns in the tent-making bat Artibeus watsoni

Space use and ranging patterns of individuals have traditionally been used to identify social systems, and the amount of overlap in the home ranges of individuals can provide indirect information about the likelihood of social interactions. We compared data on foraging and roosting range overlap of the tent-roosting bat Artibeus watsoni to assess how environmental and demographic factors may affect movement patterns and social interactions. We estimated the overlap of foraging and roosting ranges among simultaneously radiotagged dyads and calculated a simple association index among these individuals. We then used these data to determine whether relative population and roost abundance, as well as sex class, affected spatial and social patterns. Our results show that range overlap in A. watsoni significantly determines the degree to which individuals interact with each other. We also found that roosting range overlap may be a greater determinant of daytime social interactions than foraging range overlap, because roosting range overlap showed a stronger correlation with association patterns. In addition, the differences that we observed in roosting range overlap and association among dyads were a consequence of the effects of population and roost density. Bats sampled in areas of high-population abundance had significantly higher roosting range overlap than bats in areas of low-population abundance, and roosting ranges of bats sampled at sites with few roosting resources (i.e. tents) overlapped more than those of bats living in areas with more tents. Finally, we observed no overlap in roosting range and no association among adult males, supporting the hypothesis that males defend tents or roosting areas against other males to gain exclusive mating access to females using these structures.

THE DIVERSITY OF DUNITES

The Wadi Tayin massif in the Oman ophiolite which is representative of a fast spreading situation offers the thickest mantle section (up to 15km, exposed on 1250 km2). It has been the site of the most extended petrostructural investments. In this massif, the size, structure and distribution of dunites is far from being uniform. The basal section (~3km thick) affected by the pre-detachment solid state flow contains large dunites (1 to 40%, up to 50m thick), which are flat-lying and concordant with respect to the peridotite low-T foliation; they constitute the ‘banded unit’. The main section (up to 12km thick) contains large dunites, few tens of meters thick (like the Batin dunite, Fig.1) which are also flat-lying but discordant with respect to the peridotite high-T foliation. There are also thin dunites (1 to 50cm thick), which are either concordant and parallel to the banding, or discordant and often expressed as reaction zones along gabbro or pyroxenite dykes or chromite schlierens (maximum 1m thick). The thick Moho transition zone (~500 m in the western part of the massif) is formed by large concordant flat dunites, interlayered dominantly with depleted harzburgites downsection and with gabbro sills upsection. In the main section, as shown in the Batin area by detailed mapping, the thick dunites are not transposed parallel to the high-T foliation of the enclosing harzburgites. They have retained their flat attitude and initial thickness. These large flat dunites are interpreted, based on trace elements geochemistry, as resulting from melt-rock reaction at high melt/rock ratios at the asthenosphere/lithosphere thermal boundary. The same interpretation is proposed for the dunites set at the base of the mantle section. Associated or not with reactive mafic dikes, only thin discordant dunite veins and concordant bands could represent traces of late and early melt extraction channeling, respectively. These structural constraints are discussed in reference to previous melt extraction models. In the Lanzo massif of the Piemont Alps, dunite lenses as well as gabbro dikes, both reactive and intrusive, are concentrated in a western domain represented by the southwestern body and the western margin of the central body. They lie presumably close below the overlying oceanic crust represented by the metamorphic serpentinites and mafic rocks of the Viu zone. One group of dunite lenses are subconcordant and associated with olivine gabbro dykes, thus coeval of high-T mantle flow; the second group located in the Monte Arpone area are discordant and associated with parallel ferrogabbro dikes. Whatever the melt extraction model leaving residual dunite lenses, this process is controlled by a thermal boundary, and dunites do not image a steady state process of melt extraction from the mantle.