Do habitat characteristics determine mortality risk for bats at wind farms? Modelling susceptible species activity patterns and anticipating possible mortality events

Effects of turbine height and cut-in speed on bat and swallow fatalities at wind energy facilities

Understanding the relationship between the height of wind turbines and wildlife fatalities is important for informing and mitigating wildlife collisions as ever taller and denser arrays of wind turbines are erected across the landscape. We examined relationships between turbine height and fatalities of bats and swallows at 811 turbines in Ontario, Canada, ranging from 119 to 186 m tall. We accounted for cut-in speeds, operational mitigation, and taller turbines projecting carcasses farther from the turbine base than shorter turbines. Fatalities of hoary bats ( Lasiurus cinereus Palisot de Beauvois, 1796), silver-haired bats ( Lasionycteris noctivagans Le Conte, 1831), and big brown bats ( Eptesicus fuscus Palisot de Beauvois, 1796) increased with increased maximum blade height of turbines. In contrast, fatalities of little brown bat ( Myotis lucifugus Le Conte, 1831) and eastern red bat ( Lasiurus borealis Müller, 1776) decreased with increased turbine height. Fatalities of purple martins ( Progne subis Linnaeus, 1758) and tree swallows ( Tachycineta bicolor Vieillot, 1808) were higher at taller turbines than shorter turbines. However, fatalities of cliff swallow ( Petrochelidon pyrrhonota Vieillot, 1817) and barn swallow ( Hirundo rustica Linnaeus, 1758) were not associated with turbine height. Our results suggest that varying flight height among species may be one factor affecting collision risk.

Hazards of wind turbines on avifauna - a preliminary appraisal within the Indian context

Wind farms are substantial sources of renewable energy in India; however, their spread across the country potentially present new hazards to local and migratory birds.  This study explored the risk of electrocution and collision of birds with wind turbines close to eco-sensitive zones in India, including Bakkhali, a UNESCO World Heritage site.  Geographic information system and remote sensing technology were used.  The results indicate vulnerability of local bird species such as barn owl, Indian Scops Owl, Blue Rock Pigeon, Asian Koel, House Crow, Common Sandpiper, Common Snipe, Ruddy Shelduck, Lesser Whistling Duck, Cattle Egret, Great Egret, and Pond Herons, as well as migratory species such as Bar-headed Goose, Red-crested Pochard, and American Black Duck.  Modification of wind turbine design and location were considered determinant factors to reduce risk of bird collisions.

Is wind energy increasing the impact of socio-ecological change on Mediterranean mountain ecosystems? Insights from a modelling study relating wind power boost options with a declining species

The growing concern about future challenges of energy security and climate change has led to the expansion of renewable energy production, with a special emphasis on wind power. Despite the environmental advantages of wind power, it's important to assess the impacts caused by the presence of wind farms on wildlife, particularly on species also affected by habitat loss and degradation. In Mediterranean Europe, the skylark (Alauda arvensis) is a declining passerine that breeds in mountain habitats vulnerable to the abandonment of traditional management practices and climate change. We have created a spatially explicit agent-based model (ABM) in order to replicate the selection of territories, evaluating the effect of wind farms on the mortality rate of breeding males. We were especially interested in assessing the mortality rates related with the interplay between habitat loss due to socio-ecological change and increasing wind power using alternative strategies: adding wind turbines or substituting existing wind turbines by more powerful ones, i.e. repowering. Several known aspects related with the risk of collision of A. arvensis with wind turbines were considered, particularly regarding the male habitat selection and behaviour displayed throughout the breeding season. By simulating a sequential contraction of suitable habitat for the species, we found a substantial increase in the breeding territories superimposed to the wind farm influence zone. In these conditions males' relative mortality was predicted to suffer significant increases. For equivalent wind power, adding wind turbines produced significant increases in the males' relative mortality, whereas repowering didn't. Based on our findings we propose repowering as a defensible strategy to increase wind energy production without increasing A. arvensis collision risk. We highlight that this strategy might also benefit other vulnerable bird and bat species associated with declining habitats of mountain ridges in the Mediterranean region.

A modelling framework to predict bat activity patterns on wind farms: An outline of possible applications on mountain ridges of North Portugal

Worldwide ecological impact assessments of wind farms have gathered relevant information on bat activity patterns. Since conventional bat study methods require intensive field work, the prediction of bat activity might prove useful by anticipating activity patterns and estimating attractiveness concomitant with the wind farm location. A novel framework was developed, based on the stochastic dynamic methodology (StDM) principles, to predict bat activity on mountain ridges with wind farms. We illustrate the framework application using regional data from North Portugal by merging information from several environmental monitoring programmes associated with diverse wind energy facilities that enable integrating the multifactorial influences of meteorological conditions, land cover and geographical variables on bat activity patterns. Output from this innovative methodology can anticipate episodes of exceptional bat activity, which, if correlated with collision probability, can be used to guide wind farm management strategy such as halting wind turbines during hazardous periods. If properly calibrated with regional gradients of environmental variables from mountain ridges with windfarms, the proposed methodology can be used as a complementary tool in environmental impact assessments and ecological monitoring, using predicted bat activity to assist decision making concerning the future location of wind farms and the implementation of effective mitigation measures.

Factors associated with bat mortality at wind energy facilities in the United States

Hundreds of thousands of bats are killed annually by colliding with wind turbines in the U.S., yet little is known about factors causing variation in mortality across wind energy facilities. We conducted a quantitative synthesis of bat collision mortality with wind turbines by reviewing 218 North American studies representing 100 wind energy facilities. This data set, the largest compiled for bats to date, provides further support that collision mortality is greatest for migratory tree-roosting species (Hoary Bat [Lasiurus cinereus], Eastern Red Bat [Lasiurus borealis], Silver-haired Bat [Lasionycteris noctivagans]) and from July to October. Based on 40 U.S. studies meeting inclusion criteria and analyzed under a common statistical framework to account for methodological variation, we found support for an inverse relationship between bat mortality and percent grassland cover surrounding wind energy facilities. At a national scale, grassland cover may best reflect openness of the landscape, a factor generally associated with reduced bat activity and abundance that may also reduce turbine collisions. Further representative sampling of wind energy facilities is required to validate this broad pattern. Ecologically informed decisions regarding placement of wind energy facilities involves multiple considerations, including not only factors associated with bat mortality, but also factors associated with bird collision mortality, indirect habitat-related impacts to all species, and overall ecosystem impacts.