Wind Energy and Wildlife Interactions

Sheringham Shoal Offshore Wind Farm (OWF), comprised of 88 3.6 MW turbines, was built within foraging range of Sandwich Tern Thalasseus sandvicensis breeding at a European designated site. Boat-based surveys (n = 43) were used to investigate changes in tern abundance within the site and within 0–2 and 2–4 km buffer areas before and throughout the construction of the OWF, over a study period between 2009 and 2012. Visual tracking of individual birds (n = 840) was also undertaken to document any changes in behaviour. This study is amongst the few to detail the response of a breeding seabird to the construction of an OWF. Navigational buoys in the 0–2 km buffer were used extensively by resting and socialising birds, especially early in the breeding season. Visual tracking illustrated avoidance of areas of construction activity and birds surprisingly kept their distance from installed monopiles. Avoidance was strengthened during turbine assembly, with around 30% fewer birds entering the wind farm, relative to the pre-construction baseline. Flight lines of birds that entered the site were generally along the centre of rows between turbines. A focus on transit flight meant that feeding activity was lower in the site than the buffer areas. As the site remained permeable to terns flying to and from foraging grounds further offshore, the overall abundance within the site was not significantly reduced. Although a number of the responses observed were unforeseen by Environmental Impact Assessment, the overall conclusion of only minor adverse effects was upheld. Analysis of further data from the operational site is now planned.

Collisions of birds with wind turbines are a focal point when discussing the implications of renewable energies on nature conservation. The project “Prognosis and assessment of collision risks of birds at wind turbines in northern Germany” (PROGRESS) focused on the extent and consequences of bird mortality at wind turbines.

Collision victims were searched in five search efforts from spring 2012 to spring 2014 (three spring and two autumn field searches of 12 weeks). 46 different wind farms were examined. The total searched transect length amounted to 7672 km. With a total of 291 birds found, an average of one bird was found every 27 km. Common bird species with habitat use (feeding and staging) of the wind farm area prevail the list of fatalities found. Birds of prey did not dominate the list. Nocturnal broad front migratory songbirds (especially thrush species) were hardly represented among the fatalities. The total number of fatalities was estimated incorporating search efficiency and carcass removal experiments.

An extrapolation of the results for the entire project area leads to an annual mortality of around 8500 Common buzzards, 11,300 Wood pigeons and 13,000 Mallards. Based on the breeding population in the project area this translates to 0.5% of Wood pigeons, 5.0% of Mallards and 7% of Common buzzards (assuming 50% floaters).

Results of vantage point watches indicate that the species-specific collision risk with wind turbines largely differs between species as a result of clear behavioural differences.

For the vast majority of wind farms the numbers of collision victims predicted by the Band-model were clearly below the number of collision victims estimated from carcass searches. The suitability of the Band-model for the evaluation of an anticipated collision risk for a planned wind farm at an ‘average’ onshore site is limited.

Four modelled populations of Common buzzard in northern Germany are predicted to decline when incorporating the median estimates of additional mortality derived from fatality estimates.

Statutory species protection conflicts might not always be adequately solvable for an individual project. Therefore, overarching solutions are required to accompany the further expansion of wind farms, which ensure that this does not lead to a severe decline of certain bird species that are particularly affected by collisions. Specifically, the following strategies need to be addressed:

For this study, a methodology was developed for assessing impacts of wind energy generation on populations of birds and bats at regional to national scales. The approach combines existing methods in applied ecology for prioritizing species in terms of their potential risk from wind energy facilities and estimating impacts of fatalities on population status and trend caused by collisions with wind energy infrastructure. Methods include a qualitative prioritization approach, demographic models, and potential biological removal. The approach can be used to prioritize species in need of more thorough study as well as to identify species with minimal risk. However, the components of this methodology require simplifying assumptions and the data required may be unavailable or of poor quality for some species. These issues should be carefully considered before using the methodology. The approach will increase in value as more data become available and will broaden the understanding of anthropogenic sources of mortality on bird and bat populations.

The number of wind power facilities (wind farms) has rapidly increased in Germany, with a number of these constructed in forested areas. As most bat species use forests to forage and roost, concerns have been raised in relation to the potentially higher collision risk with wind turbines in forests than in open landscapes. In addition, the standard curtailment algorithms used in open landscapes might not be appropriate in forests. An ample acoustic dataset derived from 193 nacelle height surveys of 130 individual turbines was used to investigate whether bat activity, phenology or species composition differ between forests and open landscapes. The data showed no significant differences between bats in forests and open landscape habitats, but revealed strong regional differences. Overall bat activity increases towards the east of Germany, which is mirrored by an increase of the dominant group of Nyctaloids, whereas the activity of common pipistrelles increases towards the south. These findings suggest that acoustic surveys must be interpreted on a regional and species-specific level. In summary, wind farms within forested areas do not seem not to inherently show higher bat activity at nacelle height, suggesting no increased collision risk for bats in general. However, future studies assessing bat activity at the lowest point of the rotor instead of at nacelle height are urgently needed, as well as studies that include additional variables such as proximity to bat roosts or the age of a forest.

Numerous field studies have assessed bird mortality rates in wind farms. However, results from different studies are often hard to compare due to differences in methodology. This makes it very difficult to draw conclusions and to use the results in the planning phase of new wind farms (e.g. how to mitigate impacts). In this study, it was attempted to assess how bird mortality rates are affected by (1) the location of the wind farm, (2) the spatial layout of the turbines, (3) the surrounding terrain and (4) the presence of other obstacles such as powerlines. This study involved the monitoring of 91 turbines in two contrasting wind farms in the Netherlands for five years. It used the same standardized search methodology, including experimental trials for carcass removal and search efficiency. The sites differ in location (coastal vs. inland), spatial layout, turbine dimensions, land use, bird community and flight intensity of birds. In addition, at one site powerlines were constructed halfway through the monitoring program. Any fatalities from these powerlines were also monitored in a separate monitoring program. This enabled a comparison of any differences in mortality rates or species composition between the turbine and powerline fatalities. The results show a major impact of turbine location on the number of bird fatalities, both within the same wind farm and between wind farms. Mortality rates at the coastal wind farm were three to five times higher than at the inland wind farm. By far the highest mortality rates were found at turbines close to high-tide roosts and at points where (during spring migration) migrating birds leave the coastline to cross the sea towards Germany or Scandinavia. At these turbines, mortality rates could rise up to several hundred of birds per turbine per year. When expressed in fatalities per ha, overall fatality rates of the powerlines were three times higher than of the turbines in the same area. This may be due to low visibility of the powerlines compared to wind turbines. Comparison of turbine versus powerline fatalities also showed major differences in species composition, with powerline fatalities mostly consisting of passerines and waterfowl, and turbine fatalities being dominated by gulls. As several new wind farms are planned to be realized in the coming years, the results of this study can be used in spatial planning to both assess and mitigate potential impacts.

Wind energy is considered a clean energy source, but produces negative impacts regarding avian mortality. The Barão de São João wind farm in Portugal’s Sagres region is part of an important migratory flyway, crossed by 5000 individuals of 30 soaring bird species every autumn. The wind farm’s licensing was conditioned to the implementation of rigorous mitigation procedures, namely a Radar Assisted Shutdown on Demand (RASOD) protocol to reduce the probability of bird casualties. A security perimeter with observers was aided by a radar system, detecting soaring birds approaching the wind farm. Turbines were to be turned-off when pre-defined criteria of intense migration or presence of threatened species were met. Turbine shutdown was operated by the wind farm staff after a request from the monitoring team (MT), or directly by the MT. Of the soaring birds crossing the wind farm, 55% were recorded at altitudes associated with high collision risk. However, due to RASOD, no soaring birds died from collisions during five consecutive autumns. The average annual shutdown period decreased continuously after the first year (105 h) reaching only 15 h when the MT was given direct access to shut down operations through SCADA (the remote system to monitor and control wind turbines). Shutdown period corresponded only to 0.2–1.2% of the equivalent hours in a year’s wind farm activity. The use of radar, direct access to SCADA and cumulative experience by the MT improved the procedure’s efficiency, allowing better judgments on the application of shutdown orders. Our results indicate that RASOD may be an essential tool in reconciling wind energy production with the conservation of soaring birds.

Alarmingly high numbers of bats are being killed at wind turbines worldwide, raising concerns about the cumulative effects of bat mortality on bat populations. Mitigation measures to effectively reduce bat mortality at wind turbines while maximising energy production are of paramount importance. Operational mitigation (i.e. feathering wind turbine rotors at times of high collision risk for bats) is currently the only strategy that has been shown to substantially reduce bat mortality. This study presents a model based approach for developing curtailment algorithms that account for differences in bat activity over the year and night-time and are specific to the activity level at a certain wind turbine. The results show that easily measurable variables (wind speed, month, time of night) can predict times of higher bat activity with a high temporal resolution. A recently published collision model that was developed based on an excessive carcass search study is then applied to predict bat collision rate based on the modelled bat activity. Using the ratio of wind energy revenue and collision rate, 10 min intervals were weighted, so that turbines are stopped when collision rate is high and loss in revenue is low. A threshold of two dead bats per year and turbine resulted in a mean loss in annual revenue of 1.4%. The presented approach of acoustic monitoring at the nacelle and turbine specific curtailment has become the standard method to mitigate collision risk of bats at wind turbines in Germany.

Underwater noise caused by pile-driving during the installation of offshore foundations is potentially harmful to marine life. In Germany, the regulation authority BSH set the following protection values: Sound Exposure Level SEL = 160 dB and Peak Level L_Peak = 190 dB for Harbor Porpoises that must be complied with at a distance of 750 m to the construction site in order to avoid temporal threshold shifts. The experience over the last years shows that underwater sound produced during pile-driving, depending on many parameters and measurements, shows values of up to 180 dB_SEL and up to 205 dB_{L Peak} in a distance of 750 m. Therefore, Noise Mitigation Systems (NMS) are required to significantly minimize the underwater sound. Since 2011, NMS must be applied during all noisy offshore construction work in Germany. The Institute of Technical and Applied Physics GmbH (itap) was involved in many offshore wind farm (OWF) projects with pile-driving activities (>1000 pile installations without and with different NMS). Based on these underwater noise measurements, the tested NMS were evaluated. In this paper, a general overview of existing and tested NMS including tested system variations is provided and the measured data and influencing factors on the resulting noise reduction are discussed. Additionally, combinations of two or more NMS are measured during the construction phase, if monopiles with diameters of up to 8 m are installed. It is demonstrated what level of effect one or more NMS have on the emitted noise. However, it is shown that it is possible to install monopiles with a diameter of >6 m with noise levels below 160 dB_SEL at a distance of 750 m, if combinations of suitable NMS are used. Nevertheless, any kind of noise mitigation will have a significant influence on the ‘disturbed’ or treated area from pile-driving noise for marine mammals. The question of whether a state-of-the-art measure to reduce pile-driving noise exists will be explored, based on measured data and experiences with NMS under real offshore conditions.

Industrial wind power expanded rapidly since the earliest projects, and with this rapid expansion came understanding of wind power’s impacts on wildlife and how to measure and predict those impacts. Many of the earliest wind turbines began exceeding their operational lifespans >10 years ago, spawning plans for repowering with modern turbines. All wind turbines eventually wear out. Repowering can replace old turbines that have deteriorated to capacity factors as low as 4–12% with new wind turbines with capacity factors of 30–38%, and possibly sometimes better. At the same rated capacity, a repowered project can double and triple the energy generated from the project while reducing avian fatality rates by 60–90% when the new turbines are carefully sited. On the other hand, the grading needed for wider roads and larger pads can harm terrestrial biota, and can alter the ways that birds fly over the landscape. Larger turbines are usually mounted on taller towers, so the rotor-swept plane reaches higher into the sky and can kill species of birds and bats that were previously at lower risk. Slower cut-in speeds might increase bat fatalities, and faster cut-out speeds might increase bird fatalities. Repowering poses special problems to fatality monitoring and to estimating changes in collision rates. Differences in collision rate estimates before and after repowering can be due to climate or population cycles, changes in monitoring methods, and changes in wind turbine efficiency. Fatality monitoring could be more effective when it is (1) long-term, including when the older project was operating at peak efficiency, (2) executed experimentally, such as in a before-after, control-impact design, (3) largely consistent in methodology and otherwise adjusted for inconsistencies, and (4) sufficiently sampling the projects’ installed capacity. Another challenge is overcoming public and regulator impatience over documented wildlife fatalities. Fatality monitoring before repowering necessarily reveals project impacts. Repowering can reduce those impacts, but this message needs to be delivered effectively to a public that might be skeptical after seeing the earlier impacts and will want to see trustworthy fatality predictions going forward. Accurately predicting impacts at repowered projects can be challenging because the often-used utilization survey has fared poorly at predicting impacts, and because flight patterns can shift in the face of larger wind turbines and an altered landscape.

Thrace, in northeastern Greece, is a crucial habitat of European value for the survival of the continent’s birds of prey, and it is also designated as a priority area for the development of wind farms. Consequently, it is a valuable case study for identifying the conditions under which common ground can be found. A proactive planning system grounded on sound research and analysis and robust environmental impact assessments will direct wind farm development to the most suitable locations. It will also reduce the negative impacts of wind farms and reduce the time and resources required for the approval of individual projects, while improving the reputation of the wind energy sector.

The European Union’s Birds and Habitats Directives and Marine Strategy Framework Directive demand that the proponent describes and assesses the potential cumulative effects on wildlife in environmental impact assessment reports for proposed actions. Based upon the DPSIR (Driving forces, Pressures, States, Impacts, Responses) approach (European Environment Agency 1999), a 6-step framework for undertaking a cumulative impacts assessment was developed to address this requirement:The first application of this approach was carried out for the initiative of the Dutch Social Economic Council, the Energy Agreement for Sustainable Growth (2013). The agreement proposed an offshore wind capacity of 4500 MW by 2030 for the Dutch part of the North Sea. The application of this cumulative impacts assessment framework showed that effective mitigation measures are required to achieve this agreement without endangering protected species and habitats, in line with European Union (EU) nature and environmental legislation. Mitigation measures can be implemented through conditions on permits for offshore wind farm projects, which include restrictions on the maximum underwater noise levels during construction, the minimum capacity of individual wind turbines, and measures to reduce bird and bat collisions and fatalities during seasons of major migration.

The impacts of wind turbines on birds have been discussed in Germany for almost 25 years now. The current practices in the planning process for wind farms can be characterized as a mixture of scientifically based knowledge and precautionary assumptions. The basic principle of mitigating the impacts of wind farms on certain species of high conservation concern is to maintain a sufficient distance between wind turbines and breeding sites or important roosting areas. This paper uses examples of certain species of concern to illustrate the current knowledge and practice of mitigating impacts on birds in Germany. The results demonstrate that, in some cases, the impact is not as severe as originally assumed and that micrositing of turbines can be a powerful tool to minimize possible effects. In view of the growing number of wind turbines operating in Germany, the adequate assessment of cumulative impacts is a key issue. In addition, there is growing pressure to improve and demonstrate the effectiveness of mitigation measures. Future research should be focused on long-term effects and on population-level impacts.

Concurrent with the development of wind energy, research activity on wind energy generation and wildlife has evolved significantly during the last decade. This chapter presents an overview of remaining key knowledge gaps, consequent future research directions and their significance for management and planning for wind energy generation. The impacts of wind farms on wildlife are generally site-, species- and season-specific and related management strategies and practices may differ considerably between countries. These differences acknowledge the need to consider potential wildlife impacts for each wind farm project. Still, the ecological mechanisms guiding species’ responses and potential vulnerability to wind farms can be expected to be fundamental in nature. A more cohesive understanding of the causes, patterns, mechanisms, and consequences of animal movement decisions will thereby facilitate successful mitigation of impacts. This requires planning approaches that implement the mitigation hierarchy effectively to reduce risks to species of concern. At larger geographical scales, population-level and cumulative impacts of multiple wind farms (and other anthropogenic activity) need to be addressed. This requires longitudinal and multiple-site studies to identify species-specific traits that influence risk of mortality, notably from collision with wind turbines, disturbance or barrier effects. In addition, appropriate pre- and post-construction monitoring techniques must be utilized. Predictive modelling to forecast risk, while tackling spatio-temporal variability, can guide the mitigation of wildlife impacts at wind farms.

As the need for clean low carbon renewable energy increases worldwide, wind energy is becoming established in many nations and is under consideration in many more. Technologies that make land-based and offshore wind feasible, and resource characterizations of available wind, have been developed to facilitate the advancement of the wind industry. However, there is a continuing need to also evaluate and better understand the legal and social acceptability associated with potential effects on the environment. Uncertainty about potential environmental effects continues to complicate and slow permitting (consenting) processes in many nations. Research and monitoring of wildlife interactions with wind turbines, towers, and transmission lines has been underway for decades. However, the results of those studies are not always readily available to all parties, complicating analyses of trends and inflection points in effects analyses. Sharing of available information on environmental effects of land-based and offshore wind energy development has the potential to inform siting and permitting/consenting processes. WREN Hub is an online knowledge management system that seeks to collect, curate, and disseminate scientific information on potential effects of wind energy development. WREN Hub acts as a platform to bring together the wind energy community, providing a collaborative space and an unbiased information source for researchers, regulators, developers, and key stakeholders to pursue accurate predictions of potential effects of wind energy on wildlife, habitats, and ecosystem processes. In doing so, WREN Hub ensures that key scientific uncertainties are identified, tagged for strategic research inquiry, and translated into effective collaborative projects.