| 1. |
- Ancillotto, Leonardo, et al.
(författare)
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Coastal cliffs on islands as foraging habitat for bats
- 2014
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Ingår i: Acta Chiropterologica. - 1508-1109. ; 16:1, s. 103-108
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Tidskriftsartikel (refereegranskat)abstract
- Small islands usually show simplified ecosystems with limited availability of suitable foraging habitats for bats, thus habitat selection on islands may differ compared to the mainland. Habitats that are marginal on the mainland may be important on islands. The island of Capri consists, to a large extent, of steep limestone cliffs and Mediterranean shrubland, with virtually no forests or other habitats preferred by bats on the mainland. In this study we tested the hypothesis that in resource-limited systems, such as islands, habitats generally deemed of minor value for bat foraging, such as cliffs, may become important. We conducted an acoustic survey of bats in Capri ( SW Italy), comparing their use of Mediterranean shrubland and limestone cliffs. We found that cliffs provided the preferred foraging habitat in four of the five species tested. Noticeably, even the barbastelle bat Barbastella barbastellus, normally considered a forest specialist, selected coastal cliffs as foraging habitat. Our observations indicate that the paucity of foraging habitats on islands may strongly alter the habitat use by bats. This has important implications for conservation of bats in insular environments.
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| 2. |
- Apoznański, Grzegorz, et al.
(författare)
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Barbastelle bats in a wind farm : are they at risk?
- 2018
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Ingår i: European Journal of Wildlife Research. - : Springer Science and Business Media LLC. - 1612-4642 .- 1439-0574. ; 64:4
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Tidskriftsartikel (refereegranskat)abstract
- We need to know if and how western barbastelles Barbastella barbastellus are affected by wind farming in Sweden. This is because wind turbines are frequently constructed in barbastelle habitats and yet there is no national guideline on how the arising conflict should be handled. We studied the movement, behavior and mortality of a barbastelle population at a wind farm in southern Sweden, using radio-telemetry, automatic bat detectors and carcass searches. The tagged bats (6 males and 8 females) roosted mainly under loose bark of dead oak trees and foraged in patches of mature deciduous woodlands or pockets of mature spruce trees within 15 km of the roosts. Extensive areas of young spruce plantation, open farmland and lakes were not used for roosting or foraging but were crossed by commuting bats. Continuous recordings with bat detectors frequently picked up barbastelles at forest edges 30 m from the turbines, but rarely over the turbine pads within 10 m from the turbines and never at heights of 30 and 100 m at the turbine towers. Barbastelles were apparently not attracted to the wind turbines and did not seem to interact with them in any way. Carcass searches under 10 wind turbines at 1-week intervals over three summers did not reveal any dead barbastelles, although three other species were recovered. We conclude that wind farming is not nessarily incompatible with effective conservation of barbastelles in Sweden, but instead of focusing on wind turbines, effors should concentrate on (a) preservation and restoration of mature, age-structured deciduous woodlands and spruce forests, including very small and isolated patches, which provide food and roosts, and probably also (b) avoidance of outdoor lighting in areas used by barbastelles. Designating large circular buffer zones around each known or suspected colony according to current practice would be inefficient or meaningless in our case, because barbastelles use extensive home ranges and switch roost frequently. We argue that barbastelle management must be applied on a landscape scale.
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| 3. |
- Apoznański, Grzegorz, et al.
(författare)
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Barbastelles in a Production Landscape : Where Do They Roost?
- 2021
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Ingår i: Acta Chiropterologica. - 1508-1109. ; 23:1, s. 225-232
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Tidskriftsartikel (refereegranskat)abstract
- Extensive areas of old forests have declined all over the temperate regions of Europe mainly due to extensive forestry. This is likely to have negative impact on bats that roost in trees, such as the western barbastelle Barbastella barbastellus. We investigated its selection of summer roosts in a commercially used landscape in southern Sweden. We captured and radio-tracked 14 bats and found 17 occupied roosts. Nine of the roosts, including two used by a maternity colony (ca. 30 females), were located between overlapping boards on the gables of barns. The remaining eight roosts, all used by single individuals, were under lose bark on thin trees (DBH = 0.2-0.35 m). All recorded roosts had entrances pointing downwards, were adjacent to deciduous trees providing protective darkness, and were in areas without artificial lighting. In the barns, the bats avoided the northern aspect, which is the lightest (sun sets in the NW and rises in the NE). Roost temperatures did not differ between tree-and barn roosts. Average ambient light intensity on emergence and return was 13.3 lux (SD = 10.1 lux). Roosts in trees and barns shared common physical characteristics, yet despite this both maternity roosts were located in barns, perhaps because such roosts had more space than available tree roosts. Our results suggest that in areas deprived of large trees and extensive old forest, barbastelle shows flexibility in roost selection, although they consistently avoid artificial lights of all kinds. An abundance of potential roosts in trees and buildings and absence of light pollution are therefore key elements in a holistic conservation program for this species.
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| 4. |
- Arnett, Edward B., et al.
(författare)
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Impacts of wind energy development on bats : A global perspective
- 2015
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Ingår i: Bats in the Anthropocene: Conservation of Bats in a Changing World. - Cham : Springer International Publishing. - 9783319252209 - 9783319252186 ; , s. 295-323
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Bokkapitel (refereegranskat)abstract
- Wind energy continues to be one of the fastest growing renewable energy sources under development, and while representing a clean energy source, it is not environmentally neutral. Large numbers of bats are being killed at utility-scale wind energy facilities worldwide, raising concern about cumulative impacts of wind energy development on bat populations. We discuss our current state of knowledge on patterns of bat fatalities at wind facilities, estimates of fatalities, mitigation efforts, and policy and conservation implications. Given the magnitude and extent of fatalities of bats worldwide, the conservation implications of understanding and mitigating bat fatalities at wind energy facilities are critically important and should be proactive and based on science rather than being reactive and arbitrary.
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| 5. |
- Brydegaard, Mikkel, et al.
(författare)
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High Dynamic Range in Entomological Scheimpflug Lidars
- 2021
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Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - 1077-260X. ; 27:4
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Tidskriftsartikel (refereegranskat)abstract
- Minimizing insecticide use, preventing vector diseases and facilitating biodiversity assessments are suitable applications of recent advances in photonic insect surveillance and entomological lidar. The tools also comprise a new window into fundamental aspect of the fascinating life and ecology of insects and their predators in situ. At the same time, it is evident that lidars are subject to finite detection range given by the instrument noise and saturation levels, and therefore, intervals of the biomass spectra are sectioned at different ranges. The Scheimpflug lidar allows an interesting trade-off between high sample rate and low pulse energy for retrieving wing beat harmonics and slow sample rates with high pulse energy for detecting small species far away. In this paper, we review and revise calibration, sizing and associated deficiencies, and report count rates to 104 insects/minute up to 2 km range. We investigate if and how high dynamic range can be exploited in entomological lidar and also how fast and slow sample rates could complement each other and capture a wider span of the biomass spectrum. We demonstrate that smaller insect can be detected further away by long exposures and show consistency between the captured biomass size spectra. However, we find unexpected discrepancies between short and long exposures in the range distributions. We found that vertebrates as well as specular insects can saturate signals. Error sources and limitations are elaborated on.
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| 6. |
- Chou, Cheng Han, et al.
(författare)
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Bat fatalities at wind farms in Taiwan
- 2017
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Ingår i: Mammal Study. - : Mammalogical Society of Japan. - 1343-4152 .- 1348-6160. ; 42:2, s. 121-124
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Tidskriftsartikel (refereegranskat)abstract
- We collected bat carcasses at three wind farms in Taiwan, located along the west coast mostly near the sea and/or in former coastal wetland habitats. We found 43 bat carcasses, mostly of common aerial-hawking species such as Pipistrellus abramus and Scotophilus kuhlii, but the island endemics Eptesicus serotinus horikawai and Myotis formosus flavus were also recovered. All bat species affected are believed to remain on the island all year. As far as we know this is the first report of bat fatalities at wind energy facilities in eastern Asia.
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| 7. |
- Eklöf, Johan, et al.
(författare)
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Attitudes towards Bats in Swedish History
- 2021
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Ingår i: Journal of Ethnobiology. - : Society of Ethnobiology. - 0278-0771. ; 41:1, s. 35-52
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Tidskriftsartikel (refereegranskat)abstract
- Bats have always fascinated people by their unusual appearance, but fear towards them is also common, particularly in Western societies. Making headlines worldwide during the recent COVID-19 pandemic, bats were all too often accused of carrying and transmitting a disproportionate share of dangerous viruses. We enquired about the origin and persistence of this thinking in Sweden by searching old literature and original museum records where bats are mentioned. In the Bible, the bat is an explicitly unclean animal. At least since the Middle Ages, it has been used as a symbol of the Devil, with the dark skin wings in deliberate contrast to the white wings of angels. However, according to our folklore records, the bat was usually seen in a different and generally positive context by the people, and was treated with respect. Its magic properties, particularly contained in the blood, eyes, and wings, could bring fortune and prevent bad luck in various everyday contexts. A minority of records refer to bats being used in witchcraft, black magic, or, following the religious dogma, claiming that they are ugly or unclean and cannot be the work of God. We found no indication that bats were considered aggressive, dangerous, or to carry disease. Hence, we surmise there was little fear of bats in Swedish (Nordic) history, despite the religious message. Hence, the general attitude towards bats in the past seems to have been opposite to the view currently met in Western societies.
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| 8. |
- Jansson, Samuel, et al.
(författare)
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A Scheimpflug lidar used to observe insect swarming at a wind turbine
- 2020
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Ingår i: Ecological Indicators. - : Elsevier BV. - 1470-160X. ; 117
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Tidskriftsartikel (refereegranskat)abstract
- Wind turbines have considerable impact on flying animals, particularly bats, which are sometimes killed in large numbers by the moving rotors. A longstanding question remains why bats are attracted to wind turbines and risk their lives among the moving rotor blades. One hypothesis is that they feed on insects swarming around the turbine towers and another is that they congregate there to court. The two are not mutually exclusive and may occur more or less simultaneously. It has been difficult to distinguish these hypothesis, because techniques that permit observations of small insects over the relevant distances (~100 m) in the dark are lacking. In this study, we monitored insects at the top of a wind turbine using a novel high-resolution Scheimpflug lidar. The instrument was employed around dusk during ten late summer nights in 2018, with the principal aim to evaluate its performance under real field conditions. Insect swarms were observed near the top of the turbine tower on every night. They appeared in short intervals and varied in density, timing, exact location and size of the swarming insects from day to day. Swarms formed in the afternoon and either dispersed around sunset before the emergence of bats, or remained until darkness, when bats arrived at the turbine. Some of the bats fed there, as indicated by ultrasonic feeding-buzzes, and also engaged in social interactions possibly including courtship, as indicated by song-flights. Daily variation in the formation, dispersal and behavior of the insect swarms appeared to be influenced by temperature and wind speed and also differed among the insect species.
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| 9. |
- Malmqvist, Elin, et al.
(författare)
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The bat–bird–bug battle : Daily flight activity of insects and their predators over a rice field revealed by high-resolution scheimpflug lidar
- 2018
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Ingår i: Royal Society Open Science. - : The Royal Society. - 2054-5703. ; 5:4
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Tidskriftsartikel (refereegranskat)abstract
- We present the results of, to our knowledge, the first Lidar study applied to continuous and simultaneous monitoring of aerial insects, bats and birds. It illustrates how common patterns of flight activity, e.g. insect swarming around twilight, depend on predation risk and other constraints acting on the faunal components. Flight activity was monitored over a rice field in China during one week in July 2016, using a high-resolution Scheimpflug Lidar system. The monitored Lidar transect was about 520 m long and covered approximately 2.5 m3. The observed biomass spectrum was bimodal, and targets were separated into insects and vertebrates in a categorization supported by visual observations. Peak flight activity occurred at dusk and dawn, with a 37 min time difference between the bat and insect peaks. Hence, bats started to feed in declining insect activity after dusk and stopped before the rise in activity before dawn. A similar time difference between insects and birds may have occurred, but it was not obvious, perhaps because birds were relatively scarce. Our observations are consistent with the hypothesis that flight activity of bats is constrained by predation in bright light, and that crepuscular insects exploit this constraint by swarming near to sunset/sunrise to minimize predation from bats.
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| 10. |
- Michaelsen, Tore Christian, et al.
(författare)
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Uncertainty and ignored information in the analysis of bat ultrasound : Bayesian approximation to the rescue
- 2022
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Ingår i: Ecological Informatics. - : Elsevier BV. - 1574-9541. ; 70
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Tidskriftsartikel (refereegranskat)abstract
- Bat ultrasound analysis has been around for several decades and it is one of the most important tools in studies of bat ecology. Discrimination between species is based on intra-specific features of echolocation calls. Identification of species and genera in audio files can be attempted either manually or through software which performs a fully automated discrimination between species. However, significant overlap in various features (e.g. frequencies of calls) exists between species and even genera. Species ID is therefore often not an absolute conclusion, but rather an opinion or best guess, as opposed to DNA tests or measurements on external characters of captured bats. To make things even worse, the probability of actually observing a bat of a given species in space and time is ignored when performing bat ultrasound analysis. This study introduces Bayesian approximation through a new method we have named Alternative Bayesian Bat Analysis (ABBA). We show, through a simple proof-of-concept example, the importance of adding information about the local composition of the bat community, hence making informed decisions regarding which species is most likely present in audio files. The superior performance of ABBA is also shown through an example using R code. Here, we use simulated data for three Pipistrellus spp., a genus with significant overlap in frequencies, but the code can easily be adapted to other bat species and genera worldwide. ABBA outperformed the non-Bayesian approach for all three species. The rare species in the simulated data set was super-inflated when using the non-Bayesian method. Further the results show, contrarily to common belief, that the frequency dominated by a given species in a data set, depends on the composition of the bat fauna and not just means and SDs reported in the literature. ABBA allows researchers to include all observations in statistical modeling, rather than excluding observations, an approach which can affect the reliability of studies. This study also, to a great extent, explains the poor performance of software attempting automated bat ID. Implementing Bayesian algorithms, and thereby allowing users to interact with the software, should significantly improve their performance.
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