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Gefahren künstlicher Beleuchtung für ziehende Vögel und Fledermäuse. - Artificial light as a threat for birds and bats.
Abstract and Figures
This paper compiles the state of knowledge on the effects of artificial light on flying birds and bats, namely in order to deduce recommendations for bird- and bat-friendly navigation lights at wind energy turbines (WEA). More than 400 studies have been evaluated with regard to their relevance to the problem. Selected papers on orientation mechanisms which are closely related to ambient light and may therefore be of great importance for further insights into the subject area of light attraction were included.
”Mass collisions“ of birds as described for illuminated vertical structures (transmission towers/masts, lighthouses, high buildings etc.) could not be observed at illuminated WEA so far. Compared to unlighted facilities, the collision rates tend to be higher at illuminated facilities onshore. For offshore facilities, however, a high risk can be assumed due to the constant obstruction lights for shipping traffic. Constant light and intermittent light with longer light periods respectively likely increase the attraction of birds under fog, drizzle, rain, snowfall, low visibility, heavy clouds or comparable conditions of poor visibility. Findings on effects of specific light colours are contradictory.
The knowledge about bat collisions at WEA and the corresponding related factors is low. A direct attraction of bats by WEA-lighting is not verified so far. Light sources, especially ultraviolet light-emitting lamps, do affect bats mainly indirectly by the attraction of insects. The red intermittent or constant light that is used for WEA marking in the USA does neither cause a significant aggregation of insects nor higher collision rates compared to unlighted facilities. There are hints on higher collision rates for facilities that are illuminated with strobe lights. The number of bat collisions at WEA tends to increase in warm, calm weather conditions when the animals’ activity is high. Low visibility, heavy clouds, drizzle and fog apparently also increase the collision risk.
Concerning the lighting design necessary to ensure a safe air and ship traffic at a tall structure, intermittent light with a short “on” phase and a long “off” phase with the lowest possible intensity and a synchronization of the flash regime of all WEA in a wind park are recommended, while recommendations on light colour are currently not possible. In case of massive bird migration in collision-supporting weather/viewing conditions and in case of high bat activity at low wind forces which are, however, above threshold for the facility operation, a shutdown of the facility should be considered. There is still need for further research on the range of the light effects and on the significance of light intensity and light colour at identical flashing regimes.
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... This artificial mixing of predators and prey can also influence foraging behaviour and even result in competitive interactions among predators (Shields and Bildstein 1979). Aerial animals may collide with artificially lit structures such as lighthouses, lightvessels, communication towers, wind turbines or other large buildings, but also with offshore oil and gas-rigs, platforms and even brightly lit ships (Eisenbeis 2006, Gauthreaux and Belser 2006, Drewitt and Langston 2008, Ballasus et al. 2009, Mathews et al. 2015, Hüppop and Hill 2016. Birds might also get 'trapped' by artificial light (Verheijen 1960, Gauthreaux andBelser 2006) and eventually die due to exhaustion . ...
Radar is without alternatives for the study of broad‐scale aerial movements of birds, bats and insects and related issues in biological conservation. Radar techniques are especially useful for investigating species which fly at high altitudes, in darkness, or which are too small for applying electronic tags. Here, we present an overview of radar applications in biological conservation and highlight its future possibilities. Depending on the type of radar, information can be gathered on local‐ to continental‐scale movements of airborne organisms and their behaviour. Such data can quantify flyway usage, biomass and nutrient transport (bioflow), population sizes, dynamics and distributions, times and dimensions of movements, areas and times of mass emergence and swarming, habitat use and activity ranges. Radar also captures behavioural responses to anthropogenic disturbances, artificial light and man‐made structures. Weather surveillance and other long‐range radar networks allow spatially broad overviews of important stopover areas, songbird mass roosts and emergences from bat caves. Mobile radars, including repurposed marine radars and commercially dedicated ‘bird radars’, offer the ability to track and monitor the local movements of individuals or groups of flying animals. Harmonic radar techniques have been used for tracking short‐range movements of insects and other small animals of conservation interest. However, a major challenge in aeroecology is determining the taxonomic identity of the targets, which often requires ancillary data obtained from other methods. Radar data have become a global source of information on ecosystem structure, composition, services and function and will play an increasing role in the monitoring and conservation of flying animals and threatened habitats globally.
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... Some studies found that OWFs are barriers in the daytime and that lethal collisions predominately occur at night or during poor weather, while some observed that collisions were more common when good migration weather changed to fog, drizzle or tailwinds. Namely, at night and during poor weather, birds are attracted to lit structures (Hüppop et al. 2006(Hüppop et al. , 2016Ballasus et al. 2009). Hüppop et al. (2016) estimated that the mortality rate at more than 1000 human structures in the North Sea could reach hundreds of thousands of birds that had collided with turbines. ...
Offshore wind energy will substantially contribute to future energy
generation. However, the use of wind energy in marine areas has implications for marine ecosystems. The results of more than a decade of ecological research concerning offshore wind farms in Germany and abroad have revealed potential negative impacts of offshore wind farms, particularly with regards to seabirds, migrating
terrestrial birds, and marine mammals such as harbor porpoises, especially by noise effects during installation of the turbines. Depending on the location of the wind farm, effects on bat populations are also possible. Impact on fish and benthic species
are probably less relevant. There are even examples of positive (local) effects on marine biodiversity, for example, due to the introduction of a new hard substrate into ecosystems or the exclusion of fishing from the area of the offshore wind farm.
For an overall assessment of the impacts of offshore wind, the effects still have to be investigated on a cumulative and international level over the long term. A number of measures are necessary to achieve environmentally sound development of the use of offshore wind energy. Marine spatial planning is important for guiding human activities in the marine environment, such as the use of offshore
wind energy. Marine protected areas are of high relevance for protecting sensitive habitats and species. State-of-the-art mitigation measures against underwater noise are required to avoid hazards to whales. Finally, marine compensation measures can help to counterbalance adverse impacts of offshore wind farms.
... It seems likely that offshore wind facilities will also kill bats, but it is difficult or impossible to find bat fatalities at sea and no attempts to assess such fatalities have been made so far (Arnett et al. 2016). Under adverse weather conditions lit offshore structures such as platforms, lighthouses and lightvessels may attract and kill large numbers of nocturnally migrating birds (Ballasus et al. 2009, Hüppop et al. 2016. Collisions of bats with lighthouses, lit buildings and communication towers have also been reported (Saunders 1930, Terres 1956, Crawford & Baker 1981, O'Shea et al. 2016. ...
More than ten years of autonomous acoustic recording of bats’ echolocation calls at an unmanned offshore
research platform 45 km north of the island of Borkum (North Sea) were analysed in relation to season, time
of day and weather. To our knowledge this is the longest systematic dataset on offshore bat migration worldwide. Three-hundred and seventeen call sequences were recorded during typical migration times in spring and autumn and assigned to at least 23 Nathusius’ pipistrelles (Pipistrellus nathusius), 3 northern bats (Eptesicus nilssonii) and 2 Leisler’s bats (Nyctalus leisleri). Compared to the prevailing wind conditions, more bats than expected were recorded at lower wind speeds and southerly winds. Bats occurred under supporting tailwinds, but also under strong headwinds. In both seasons most bats occurred under winds from the south (i.e. crosswinds), which indicates offshore wind drift. We neither found effects of air pressure, nor of change in air pressure. Most registrations coincided with a dense cover of clouds, fog/low stratus and/or rain. From the structure of echolocation calls it can be concluded that most bats explored the platform rather than just passed it on transfer flights, some even foraged there. We conclude that most of the bats were on migration and attracted by the brightly lit platform and/or sought refuge there. This involves the risk of collisions with offshore wind turbines (which need to be brighter lit at sea than onshore). We assume that a great part of offshore bat migration takes place beyond the range of currently available techniques at greater altitudes than known so far.
... Due to inconclusive results, more recent studies need to be conducted to verify previous studies. Ballasus et al. (2009), from an evaluation of 400 studies, view artificial lighting as a threat to birds and bats and recommend reduced lighting. As lighting of turbines is not standardized, it must fall within the country's aviation transport regulations which varies. ...
During this rapid development of wind energy aiming to combat climate change worldwide, there is greater need to avoid, reduce, and compensate for impacts on wildlife: Through the effective use of mitigation, wind energy can continue to expand while reducing impacts. This is a first broad step into discussing and understanding mitigation strategies collectively, identifying the current state of knowledge and be a beneficial resource for practitioners and conservationists.
We review the current state of published knowledge, both land-based and offshore, with a focus on wind energy–wildlife mitigation measures. We state measures and highlight their objective and discuss at which project stage it is most effective (e.g. planning, construction, operation). Thereafter, we discuss key findings within current wind energy mitigation research, needing improved understanding into the efficacy of wildlife mitigation as well as research into the cost aspects of mitigation implementation. This review is divided into two articles; Part 1 focuses on mitigation measures during planning, siting, and construction, while Part 2 focuses on measures during operation and decommissioning.
A growing number of offshore wind farms have led to a tremendous increase in artificial lighting in the marine environment. This study disentangles the connection of light characteristics, which potentially influence the reaction of nocturnally migrating passerines to artificial illumination under different cloud cover conditions. In a spotlight experiment on a North Sea island, birds were exposed to combinations of light colour (red, yellow, green, blue, white), intensity (half, full) and blinking mode (intermittent, continuous) while measuring their number close to the light source with thermal imaging cameras.
We found that no light variant was constantly avoided by nocturnally migrating passerines crossing the sea. The number of birds did neither differ between observation periods with blinking light of different colours nor compared to darkness. While intensity did not influence the number attracted, birds were drawn more towards continuous than towards blinking illumination, when stars were not visible. Red continuous light was the only exception that did not differ from the blinking counterpart. Continuous green, blue and white light attracted significantly more birds than continuous red light in overcast situations.
Our results suggest that light sources offshore should be restricted to a minimum, but if lighting is needed, blinking light is to be preferred over continuous light, and if continuous light is required, red light should be applied.
The replacement of conventional lighting with energy‐saving light emitting diodes (LED) is a worldwide trend, yet its consequences for animals and ecosystems are poorly understood. Strictly nocturnal animals such as bats are particularly sensitive to artificial light at night (ALAN). Past studies have shown that bats, in general, respond to ALAN according to the emitted light color and that migratory bats, in particular, exhibit phototaxis in response to green light. As red and white light is frequently used in outdoor lighting, we asked how migratory bats respond to these wavelength spectra. At a major migration corridor, we recorded the presence of migrating bats based on ultrasonic recorders during 10‐min light‐on/light‐off intervals to red or warm‐white LED, interspersed with dark controls. When the red LED was switched on, we observed an increase in flight activity for Pipistrellus pygmaeus and a trend for a higher activity for Pipistrellus nathusii. As the higher flight activity of bats was not associated with increased feeding, we rule out the possibility that bats foraged at the red LED light. Instead, bats may have flown toward the red LED light source. When exposed to warm‐white LED, general flight activity at the light source did not increase, yet we observed an increased foraging activity directly at the light source compared to the dark control. Our findings highlight a response of migratory bats toward LED light that was dependent on light color. The most parsimonious explanation for the response to red LED is phototaxis and for the response to warm‐white LED foraging. Our findings call for caution in the application of red aviation lighting, particularly at wind turbines, as this light color might attract bats, leading eventually to an increased collision risk of migratory bats at wind turbines.
Trotz, aber auch aufgrund ihrer großen Nutzbarkeit ist die Biodiversität weltweit stark gefährdet. Diverse Untersuchungsmethoden (Abschn. 11.1) ergaben direkten Zugriff (11.2) und anthropogene Standortveränderungen inkl. Lebensraumvernichtung und Nutzungswandel (11.3) als Hauptursachen. Großen Einfluss besitzen zudem invasive Arten (Neobiota: 11.4), denen mit Schwarzen Listen begegnet werden soll. Für manche Arten stellen auch Sport- und andere Freizeitaktivitäten Gefahren dar (11.5). Der Klimawandel (Kap. 12) spielt demgegenüber bis heute noch eine geringere Rolle. Gefährdung der Biodiversität geht auch von Verkehrswegen (11.6) sowie von „Lichtverschmutzung“ aus (11.7). Auswirkungen des direkten Zugriffs und z.T. auch der Biotopvernichtung werden durch eine Liste der ausgerotteten Vögel und Säugetiere sowie Zahlen zur Überfischung der Meere belegt. Auf anthropogene Standortvernichtung wird insbesondere am Beispiel der nordwestdeutschen Hochmoore und des allgemeinen Diversitätsverlustes der mitteleuropäischen Kulturlandschaft eingegangen (Beispiele: Rückgang von Strukturelementen in einer Schweizer Gemeinde, von Feuchtgrünland in NW-Deutschland und Niederösterreich). Die Frage, ob und inwieweit der Landwirtschaft die alleinige Verantwortung hierfür zugerechnet werden darf, wird diskutiert. Außereuropäische Beispiele für eklatanten Diversitätsverlust sind der Rückgang des tropischen Regenwaldes und der Savannen sowie der ökosystemare Einfluss des Nilbarsches im Viktoria-See.
During this rapid development of wind energy aiming to combat climate change worldwide, there is greater need to avoid, reduce, and compensate for impacts on wildlife: Through the effective use of mitigation, wind energy can continue to expand while reducing impacts. This is a first broad step into discussing and understanding mitigation strategies collectively, identifying the current state of knowledge and be a beneficial resource for practitioners and conservationists. We review the current state of published knowledge, both land-based and offshore, with a focus on wind energy–wildlife mitigation measures. We state measures and highlight their objective and discuss at which project stage it is most effective (e.g. planning, construction, and operation). Thereafter, we discuss key findings within current wind energy mitigation research, needing improved understanding into the efficacy of wildlife mitigation as well as research into the cost aspects of mitigation implementation. This paper is divided into two articles; Part 1 focuses on mitigation measures during planning, siting, and construction, while Part 2 focuses on measures during operation and decommissioning.
Capsule Collisions with offshore structures in the North Sea could account for the mortality of hundreds of thousands of nocturnally migrating birds.Aims To assess, for the first time, the circumstances of mass fatalities at an offshore structure, including the species involved, their numbers, ages, body conditions and injuries.Methods At an unmanned tall offshore research platform in the southeastern North Sea, bird corpses were collected on 160 visiting days from October 2003 to December 2007. Corpses were identified to species and kinds of injury, ages, and fat and muscle scores were determined. Nocturnal bird calls were recorded, identified to species and quantified. Local and large-scale weather parameters were also considered.Results A total of 767 birds of 34 species, mainly thrushes, European Starlings and other passerines, were found at 45 visits. Most carcasses were in good body condition and young birds were not more affected than adults. Three quarters of 563 examined individuals had collision induced injuries. Birds in poor body condition were less likely to be collision victims than those in good condition. Mass collision events at the illuminated offshore structure coincided with increasingly adverse weather conditions and an increasing call intensity of nocturnal birds.Conclusions Assuming an average of 150 dead birds per year at this single offshore structure and additionally assuming that a considerable proportion of the corpses were not found, we estimate that mortality at the 1000 + human structures in the North Sea could reach hundreds of thousands of birds. Since offshore industrialization will progress and collision numbers at offshore turbines will consequently increase considerably, we recommend reinforced measures to reduce bird strikes at offshore structures, especially in the light of substantial declines in some migrant species.
With regard to potential sites for the construction of offshore wind farms and to their possible threats for birds it is essential to enlarge the current knowledge on bird migration above the sea – especially during the night. Within a comprehensive study for the evaluation of offshore wind farms bird calls were registered automatically on a research platform in the south-eastern North Sea. The species identification of nocturnally migrating birds is almost exclusively possible only by means of their calls. Here, we present species-specific bird occurrence near an anthropogenic offshore structure in the total daily and yearly course on the basis of automatically registered calls.
From 2004 to 2007, a total of 100 species was identified. Calls from 95,318 individuals (excluding the large gulls) were used for analyses. Three quarters were passerines (predominantly thrushes), furthermore mainly waders, terns and smaller gulls were detected. 79.4% of all individuals were registered during the night. High numbers of individuals, mostly of several species occurring together, were concentrated in only a few days/nights or even hours. Bird occurrence was much higher during autumn migration than during spring migration. A maximum of 5,236 birds of different species (corresponding to 392 Ind./h) was identified in the night from 28th to 29th October 2005. The migration periods of the short-/medium distance migrants were clearly distinguishable, otherwise not those of the long-distance passerine migrants, presumably due to their much minor ambition to call. In July mainly smaller gulls and terns, in August above all terns and waders (especially Redshank) and in winter some late smaller gulls and thrushes were registered. Generally, numbers increased continually with the beginning of the night and reached a maximum before sunrise. The fewest birds were detected in the late afternoon.
Despite methodological constraints, the shown species-specific phenologies broadly match the migration times in the offshore area of the German Bight as recovered by trapping and/or by scheduled or coincidental visual observations of bird migration. Like these methods the acoustic recording cannot cover the whole occurrence of birds. Presumably, the number of birds is underestimated during fine and overestimated during adverse weather when birds reduce flight altitude. However, we assume that the birds registered acoustically on the platform reflect at least the low flying proportion of the calling species in the course of the year and in their daily variability.
The opportunity to estimate numbers of low and thereby close to an anthropogenic obstruction flying birds using calls is – with regard to the evaluation of its collision risk and the introduction of mitigation and avoidance measures (site, short-term shutdown of the construction and optimization of illumination) – not exiguous.
1992 leiteten die Autoren, Projektleiter der Fledermaus-Gruppe
Rheinfali, ein Projekt, bei dem SchOler von zwei Kantonsschulklassen zwischen April
und Oktober den Vorbeiflug von Wasserfledermausen auf Flugstrassen zwischen
BOsingen und Rheinau gleichzeitig in Wochen-Abstanden protokoliierten.
Die Resultate bestatigten und prazisierten frO here Beobachtungen, wonach sich das
Verhalten der Wasserfledermause im Lauf der Jagdsaison in fOnf deutlich erkennbare
Teil-Saisons mit charakteristischen Merkmalen unterteilen lass!: Bestandesanstieg im
April, Mai-Peak, Standard-Bestand im Juni, Jungen-Peak Ende Juli und BestandesrOck-
gang im September. In verschiedenen Teil-Saisons verhalten sich die Wasserfleder-
mause auf einer Gruppe von Flugstrassen (in der Regel handelt es sich dabei um
Flugstrassen, die aus dem gleichen Waldabschnitt zum Jagdhabitat Ober dem Rhein
fOhren) anders als die Artgenossen auf den andern Flugstrassen, so dass wir solche
Teil-Saisons weiter unterteilen k6nnen.
1m Rahmen der vorliegenden Untersuchung fanden wir keine Beziehung zwischen
Fledermaus-Verhalten und Wetter, fOhren dies aber auf den groben Beobachtungs-
raster zurOck und schlagen Beobachtungsmethoden vor, von denen wir annehmen,
dass sie die Beziehungen zwischen Wasserfledermaus-Verhalten und Umweltpara-
metern eher erkennen lassen.
Night-migrating birds often accumulate near bright man-made light on nights with low cloud cover or rain. Mass avian mortality events associated with this phenomenon have been documented for more than 150 years. Understanding the mechanism that induces the aggregation of migrants in lighted airspace could lead to a reduction in such mortality . Toward this end, we subjected nightmigrating birds flying in dense cloud cover to alternating short periods of different artificial light characteristics. Bird aggregation occurred during periods of white, blue, and green light but not in red light or flashing white light. We discuss these results with respect to visual and magnetoreception-based aggregation theories and the phenomenon of light-induced bird mortality at tall television towers in North America.
Increased urban lighting on Kauai Island has resulted in new problems for threatened and endangered procellariiform birds. Between 1978-1985, 11 767 Newell's shearwater Puffinus puffinus newelli, 38 dark-rumped petrel Pterodroma phaeopygia sandwichensis and 8 band-rumped storm petrel Oceanodroma castro cryptoleucura were attracted to bright urban lights, struck unseen objects, and fell to the ground. A salvage effort involving public cooperation and government-run "aid stations' has returned 90% of these birds to the wild. Nightly fallout of seabirds was significantly reduced during full moon, but fallout increased as the new moon approached. The heaviest fallout occurred in urban coastal areas, particularly at river mouths. Over 97% of the fallout involved fledgling birds apparently leaving their mountain nesting grounds for the first time; <1% of these birds were recovered again on subsequent nights. -from Authors
Every year in autumn, myriads of migrating birds leave their breeding areas and start the long flight towards their wintering areas, which often are thousands of kilometres away. Migration means several weeks or even months of travelling, which may include crossing ecological barrieres, like mountains, seas and deserts. The birds have to face and solve a number of physiological and ecological problems, like meeting the energy requirements of the extended flight and finding suitable refuelling areas along the route etc. A major problem, however, concerns orientation and navigation: while adult migrants are already familiar with the route and a winter quarter that allowed their survival during the previous year, the young birds migrating for the first time have to reach their population-specific wintering area that is still unknown to them.