| 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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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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| 3. |
- Rydell, Jens, et al.
(författare)
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Bat Activity at a Small Wind Turbine in the Baltic Sea
- 2015
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Ingår i: Acta Chiropterologica. - 1508-1109. ; 17:2, s. 359-364
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Tidskriftsartikel (refereegranskat)abstract
- Activity of bats at an old wind park four km off the island of Gotland in the Baltic Sea was monitored during 50 nights from August to October 2013, using an automatic bat detector (Pettersson D500-X) mounted on one of the turbines. Single individuals or pairs of common noctules Nyctalus noctula were recorded on five occasions only (26 and 27 August), all in calm weather and when little or no rotor movement occurred. Since such conditions were unusual (five of 50 nights of observation) the visits by the bats were unlikely to be chance events (migrating bats passing the turbine), but more likely involved bats attracted to the turbines. However, no feeding buzzes were recorded and the bats never stayed near the turbine more than one minute. The turbines studied are lit by 250 W white lights and this could have been the reason why bats visited the turbines, because such lights potentially attract insects. The bats could not have been attracted to the turbines by any factor related of the movement of the rotor or the generator, such as Doppler-effects, noise, heat or electric fields.
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| 4. |
- Rydell, Jens, et al.
(författare)
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Bat mortality at wind turbines in northwestern Europe
- 2010
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Ingår i: Acta Chiropterologica. - 1508-1109. ; 12:2, s. 261-274
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Tidskriftsartikel (refereegranskat)abstract
- We reviewed published and unpublished written reports on bat mortality at wind farms in northwestern Europe. The estimated number of bats killed per turbine annually was relatively low (0-3) on flat, open farmland away from the coast, higher (2-5) in more complex agricultural landscapes, and highest (5-20) at the coast and on forested hills and ridges. The species killed almost exclusively (98%) belonged to a group (Nyctalus, Pipistrellus, Vespertilio and Eptesicus spp.) adapted for open-air foraging. The bats were killed by the moving rotor blades as they hunted insects attracted to the turbines. This occurred independently of sex and age. Peak mortality varied considerably in frequency and timing among years, but the events usually (90%) occurred on nights with low wind speeds in late July to early October and to a lesser extent (10%) also in April-June. The mortality increased with turbine tower height and rotor diameter but was independent of the distance from the ground to the lowest rotor point. It was also independent of the size of the wind park (1-18 turbines). Bat species other than the open-air suite referred to above are usually not at risk at wind turbines, because they fly below the rotors, but are still killed occasionally (2%).
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| 5. |
- Rydell, Jens, et al.
(författare)
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Long-Term Increase in Hibernating Bats in Swedish Mines - Effect of Global Warming?
- 2018
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Ingår i: Acta Chiropterologica. - 1508-1109. ; 20:2, s. 421-426
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Tidskriftsartikel (refereegranskat)abstract
- We present the result of bat winter censuses in three old mines in southern Sweden from 1980 until present (2017). The Taberg and Kleva mines, each with about 1.5 km of accessible passages, have winter populations of 517 and 132 bats, respectively (maximum counts) belonging to six species, the highest numbers known in underground sites in Sweden. Ädelfors is less extensive and has fewer individuals (maximum 22). The two former sites were protected and gated in the 1980′s while the third site still has no formal protection and is subject to disturbance. Generally Daubenton's bat Myotis daubentonii and the brown long-eared bat Plecotus auritus are common species and the numbers are stable. The whiskered and Brandt's bats M. mystacinus/brandtii and Natterer's bat M. nattereri have increased significantly, while the northern bat Eptesicus nilssonii, which is relatively rare in mines generally, has shown a slight but significant decline. At the species level the population trends conform well to those of the respective species in continental Europe and the British Isles. This suggests that there is a common factor behind the population changes across Europe. Although our data are very limited, the results question some previous explanations for the observed trends, but are in line with theoretical predictions based on global warming scenarios.
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| 6. |
- Rydell, Jens, et al.
(författare)
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Phenology of migratory bat activity across the Baltic Sea and the south-eastern North Sea
- 2014
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Ingår i: Acta Chiropterologica. - 1508-1109. ; 16:1, s. 139-147
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Tidskriftsartikel (refereegranskat)abstract
- We compiled the available information on the occurrence and timing of migratory bat activity across the Baltic Sea and south-eastern North Sea coasts and islands, based on ultrasonic monitoring projects at 19 localities in 2007-2009. The data refer to three species; Nathusius' pipistrelle Pipistrellus nathusii, soprano pipistrelle P. pygmaeus and common noctule Nyctalus noctula. Pipistrellus nathusii occurred at all sites (north to 61 degrees N in Finland), while the other species were scarcer, particularly at the northernmost sites. The status of the recorded individuals is unknown. However, the activity most likely was of migrating individuals or individuals on migration stopover, because very few observations were made during the maternity period. Spring activity occurred predominantly in May, with the median observation date of P. nathusii 20 days earlier in the south (Germany) than in the north (Finland). Autumn migration was observed throughout August and September and activity that may or may not indicate migration was also observed in October and November. The median date of such activity in autumn usually occurred in September and without any significant difference in timing in relation to latitude. Migratory bats in the Baltic area apparently move on a broad front in most cases. The estimated speed of migration for P. nathusii in spring was 55 km/day. The entire coastline and islands around the Baltic Sea are of potential importance for migrating bats in spring (April-May) and autumn (August-September) and should achieve relevant protection according to EU legislation and its implementations.
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| 7. |
- Sánchez-Navarro, Sonia, et al.
(författare)
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Bat Fatalities at Wind-Farms in the Lowland Mediterranean of Southern Spain
- 2020
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Ingår i: Acta Chiropterologica. - 1508-1109. ; 21:2, s. 349-358
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Tidskriftsartikel (refereegranskat)abstract
- Wind energy is an important source of bat mortality worldwide. Extensive mortality data were gathered by a provincial surveillance program carried out at wind farms in lowland Mediterranean areas of the province of Cadiz, Andalusia (South Spain) between 2005 and 2016. As many as 2,371 bat fatalities were found. We determined the patterns of fatality in this sample and tested the quality of the surveillance program used. The data generally support previous observations regarding the seasonal timing, the species affected and the sex and age of fatalities. However, contrary to studies made at higher latitudes, fatalities mostly (95%) affected sedentary species and occurred on wind farms in flat landscape used for farming and livestock rearing. The current operational surveillance programme did not focus on bats initially, and, consequently, we urge that an improvement should consider a standardized search methodology including bats, verification of species identity, precise data collection, and mandatory and regular scavenger-removal and search-efficiency trials, in order to obtain correctly adjusted fatality estimates that can be used for efficient mitigation or compensatory measures.
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| 8. |
- Sánchez-Navarro, Sonia, et al.
(författare)
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High bat fatality rates estimated at wind farms in southern Spain
- 2023
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Ingår i: Acta Chiropterologica. - 1508-1109. ; 25:1, s. 125-134
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Tidskriftsartikel (refereegranskat)abstract
- An astonishing number of bat fatalities (2,371 belonging to 15 species) were recovered in a provincial surveillance program at wind farms in Cádiz, at the southern tip of Spain, in 2005–2016. We carefully analysed a subset of this sample intending to estimate the true fatality rate in the year 2011, the year for which we had the richest data set (582 fatalities at 38 wind farms). To estimate the true fatality rate, we conducted search-efficiency and scavenger-removal trials in nine wind farms involving 122 turbines and 289 observed fatalities and calculated the searchable surface. An annual fatality rate of 41.1 dead bats per turbine (26.4 per MW) was estimated in the study area using a self-developed estimator due to the singularities of the surveillance program. Our estimator results are lower than those obtained using the Generalized Mortality Estimator (GenEst) developed by U.S. Geological Survey. Estimates of 37,689 or 33,370 fatalities were made according to the province's number of turbines or MW in 2011. Some areas have registered the highest fatality rates ever recorded for bats in wind turbines anywhere globally, even more so because we have been conservative. There is an urgent need for efficient preventive and mitigation measures at wind farms in risky landscapes and with a high rate of bat fatalities, but trials are also needed to know how well the post-operational monitoring is done and how far it is from reality. Clearly, current official post-construction surveillance programs are inefficient for searching bats and therefore mask a high fatality rate, mainly of sedentary bats.
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| 9. |
- Suba, Jurgis, et al.
(författare)
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Fly-and-forage strategy in the bat Pipistrellus nathusii during autumn migration
- 2012
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Ingår i: Acta Chiropterologica. - 1508-1109. ; 14:2, s. 379-385
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Tidskriftsartikel (refereegranskat)abstract
- Populations of Pipistrellus nathusii (Nathusius's bat), an insectivorous aerial-hawking species that breeds in north-eastern Europe, perform long-distance migrations between breeding sites and hibernation areas in central and southern Europe. The feeding strategy of migrating P nathusii was investigated in Latvia on the east coast of the Baltic Sea, exploring evidence for and against two non-mutually exclusive predictions that i) the bats feed shortly after dusk at highest aerial insect activity and continue to migrate thereafter or ii) apply a 'fly-and-forage' strategy and frequently interrupt their migration flight to feed. Echolocation calls and feeding buzzes of P. nathusii were recorded throughout the night from August until September on a known migration flyway over coastal dunes and at potential foraging sites in adjacent woodlands, over meadows and wetlands. The results indicate that P. nathusii applies a fly-and-forage strategy along the Baltic coast. However, a threshold in aerial insect availability may exist, below which no foraging occurs and migration continues.
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