Visual fields, foraging and collision vulnerability in gulls (Laridae)
Ibis (2025), 167, 386–396. doi:10.1111/ibi.13360
Jennifer C. Cantlay, Graham R. Martin, School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, UK
Steven J. Portugal, The Natural History Museum, Tring, and Department of Zoology, University of Oxford, UK
Visual field configurations can render some species more vulnerable to collisions with human artefacts that extend into open airspace, such as power lines and wind turbines. Visual fields have three main components: the monocular fields describe the extent of the world seen by each eye, the binocular field describes the region where the monocular fields overlap, and the blind area describes the region in which no vision is provided. Among birds, the topography of the binocular field, and the extent and position of the blind area, show considerable interspecific variation. We determined visual fields in three species of gulls (European Herring Gulls Larus argentatus, Lesser Black-backed Gulls Larus fuscus, Black-legged Kittiwakes Rissa tridactyla), and found that they show the key characteristics associated with visually guided foraging. However, the binocular field does not extend through the full height of the frontal field. This results in a blind sector, which can project in the direction of flight when gulls pitch their heads sufficiently far forwards to visually search the surface below. This could render gulls vulnerable to collisions with anthropogenic structures (power lines, wind turbines) that extend into the open airspace.
Bird Displacement by Wind Turbines: Assessing Current Knowledge and Recommendations for Future Studies
Birds 2021, 2, 460–475. doi:10.3390/birds2040034
Ana Teresa Marques and Joana Bernardino, Centro de Investigação em Biodiversidade e Recursos Genéticos (CIBIO), InBIO Laboratório Associado, Universidade do Porto, Vairão, CIBIO, InBIO Laboratório Associado, Instituto Superior de Agronomia, Universidade de Lisboa, Lisboa, and BIOPOLIS Program in Genomics, Biodiversity and Land Planning, CIBIO, Vairão, Portugal
Helena Batalha, School of Biological Sciences, University of East Anglia, Norwich, UK
Wind turbines can affect bird populations by causing mortality when birds collide with turbine blades or displacement when the individuals move permanently to other areas. While mortality is well documented, displacement has only been studied more extensively in the last decade, and it is important to summarise the current knowledge and research trends. The literature on this topic has increased in the past decade but is concentrated in Europe and United States, despite the fact that the wind industry has worldwide coverage. Open habitats—such as agricultural fields and grasslands—were the most represented and Accipitriformes, Galliformes, Charadriiformes, Anseriformes and Passeriformes were the most frequently studied taxa. Displacement was recorded in 40.6% of the trials, and Gaviiformes, Anseriformes, Suliformes, Accipitriformes and Falconiformes were the most affected groups.
The visual fields of Common Guillemots Uria aalge and Atlantic Puffins Fratercula arctica: foraging, vigilance and collision vulnerability
Ibis (2015), 157, 798–807
Graham R. Martin, School of Biosciences, University of Birmingham, Edgbaston, Birmingham, UK
Sarah Wanless, Centre for Ecology & Hydrology, Bush Estate, Penicuik, Midlothian, UK
Amphibious marine bird species are vulnerable to collisions with man-made objects both above and below water, particularly wind- and wave-driven turbines. Certain groups of birds when in ight are particularly vulnerable to collisions with power lines and turbines due to constraints on their visual fields (Martin 2011, Martin et al. 2012). The visual fields of Puffins and Guillemots would suggest that they do not have particular vulnerability when in ight because the vertical length of their binocular areas mean that they can always maintain visual coverage of the world ahead. This is unlike the situation in vultures whose binocular fields are vertically small and positioned such that when looking downwards in foraging, the birds fail to see ahead. Underwater, however, the much reduced visual fields of these auks could well render them vulnerable to underwater obstacles.
Collision risk and micro-avoidance rates of birds with wind turbines in Flanders
Bird Study (2014) 61, 220 230. doi:10.1080/00063657.2014.894492
Joris Everaert, Research Institute for Nature and Forest, Brussels, Belgium
Capsule: Local factors can lead to strong variation in mortality rate and collision risk that obscures possible effects of turbine size in wind farms.
Aims: The impact of bird collisions was studied at eight land-based wind farm sites with a total of 66 small to large turbines in order to assess the mortality rate and collision risk.
Results: Mortality rate was 21 birds per turbine per year on average. Most fatalities were local common species (e.g. gulls) but rarer species were also found (e.g. terns, raptors and waders). Collision risk of gulls was 0.05% and 0.08% on average for birds, respectively, flying at turbine and rotor height through the wind farms (0.09% and 0.14% maximum). Large gulls had a significant higher collision risk than small gulls at rotor height. Mortality rate and collision risk were not significantly related to turbine size. The results were integrated in a widely used collision risk model to obtain information of micro-avoidance, i.e. the proportion of birds that fly through the wind farm but avoid passing through the rotor swept area of the turbines. For gulls, this micro-avoidance was 96.1% and 96.3% on average for birds, respectively, flying at turbine and rotor height through the wind farms.
Conclusion: The results indicate that local factors can lead to strong variation in mortality rate and collision risk that obscures possible effects of turbine size in wind farms.
Bird mortality at a wind-energy facility near a wetland of international importance
The Condor 115(4):700–711 (2013)
Steven M. Grodsky, Christopher S. Jennelle, and David Drake
Department of Forest and Wildlife Ecology, University of Wisconsin, Madison
Wildlife Research Station, Iowa Department of Natural Resources, Boone
Birds are killed and displaced at wind facilities, so increased understanding of the drivers of mortality and displacement will assist planners considering the future placement and use of wind facilities. Our objectives were to assess the effect on birds of a wind facility in southeastern Wisconsin by (1) recording the species composition of recovered bird carcasses, (2) estimating mortality rates, and (3) identifying variables correlated with fatalities. We found 20 bird carcasses during scheduled searches. On this basis, we estimated that over two springs and two autumns of study from 2008 to 2010, 607 birds (0.026 per turbine per day, 0.017 per megawatt per day) were killed over 277 days of searching at this facility containing 86 turbines. Nocturnally migrating passerines accounted for 50% of the birds found killed. We found a significant negative relationship between bird fatalities and northward movement of birds through the wind facility. Despite the close proximity of Horicon Marsh National Wildlife Refuge, a wetland of international importance, we found no relationship between distance to Horicon Marsh and bird fatalities.
Mortalidad de Aves en un Complejo de Energía Eólica cerca de un Humedal de Importancia Internacional
Las turbinas de viento brindan una fuente de energía renovable que atienden la demanda humana creciente y compensan los costos del uso de los combustibles fósiles y de la generación de energía nuclear. Las aves mueren y son desplazadas en los complejos eólicos, por lo que un mayor entendimiento de las causas de mortalidad y desplazamiento ayudará a los planificadores a considerar el emplazamiento y uso de los complejos eólicos. Nuestros objetivos fueron evaluar el efecto sobre las aves de un complejo eólico en el sudeste de Wisconsin mediante (1) el registro de la composición de especies de los cadáveres encontrados de aves, (2) la estimación de las tasas de mortalidad y (3) la identificación de variables correlacionadas con las muertes. Encontramos 20 cadáveres de aves durante las búsquedas programadas. En base a esto, estimamos que a lo largo de dos primaveras y dos otoños de estudio desde 2008 a 2010, 607 aves (0.026 por turbina por día, 0.017 por megavatio por día) murieron a lo largo de 277 días de búsqueda en este complejo que contiene 86 turbinas. Las aves migratorias nocturnas representaron 50% de las aves muertas encontradas. Encontramos una relación negativa significativa entre las muertes de aves y el movimiento de las aves hacia el norte a través del complejo eólico. A pesar de la proximidad del Refugio Nacional de Vida Silvestre Horicon Marsh, un humedal de importancia internacional, no encontramos una relación entre la distancia a Horicon Marsh y las aves muertas.
Impacts of wind farms on swans and geese: A review
Wildfowl (2012) 62: 37–72
Eileen C. Rees, Wildfowl & Wetlands Trust, Martin Mere, Burscough, near Ormskirk, Lancashire, UK
This review considers data published on the effects of offshore and onshore windfarms on swans and geese and finds that the information available is patchy. Of 72 swans or geese reported as collision victims at 46 wind farms, most (39 birds) were reported at 23 wind farms in Germany where such data are collated. Post-construction monitoring was undertaken for 1 year at 67% of 33 sites, making it difficult to test for cumulative effects or annual variation in collision rates. Site use by the birds was measured at only nine of 46 wind farms where collisions by swans and geese were monitored or recorded. Displacement distances of feeding birds at wintering sites ranged from 100–600 m, but preliminary evidence suggested that large-scale displacement also occurs, with fewer swans and geese returning to areas after wind farms were installed. Eight studies of flight behaviour all reported changes in flight-lines for swans or geese initially seen heading towards the turbines, at distances ranging from a few hundred metres to 5 km; 50–100% of individuals/groups avoided entering the area between turbines, but in some cases the sample sizes were small.
Impact of wind turbines on birds: a case study from Gujarat, India
Scientific Journal of Environmental Sciences (2012) 1(1) 9-20
S. Ramesh Kumar, A. Mohamed Samsoor Ali, P.R. Arun
Division of Environmental Impact Assessment, Sálim Ali Centre for Ornithology and Natural History, Anaikatty, Tamil Nadu, India
Based on recent reports from certain parts of the world, there is a growing concern on the environmental impacts of wind turbines on birds. The present field study was conducted to evaluate these impacts in an Indian context. We have been studying the birds from a wind farm in Kutch District, Gujarat, India since September 2011 and our preliminary results of the past one year study is presented here. During the study span, 139 bird species were recorded which include eight near-threatened species as per IUCN Red list. Totally six bird fatalities were recorded as a result of collisions with the wind turbines. Preliminary findings of this study confirm the possible impact of wind turbines on birds in Kutch region.
Barriers to movement: Modelling energetic costs of avoiding marine wind farms amongst breeding seabirds
Marine Pollution Bulletin 60 (2010) 1085–1091. doi:10.1016/j.marpolbul.2010.01.016
Elizabeth A. Masden, Daniel T. Haydon, Boyd Orr Centre for Population and Ecosystem Health, University of Glasgow, Scotland, UK
Anthony D. Fox, Department of Wildlife Ecology and Biodiversity, National Environmental Research Institute, University of Aarhus, Rønde, Denmark
Robert W. Furness, Department of Ecology and Evolutionary Biology, University of Glasgow, Scotland, UK
Proposals for wind farms in areas of known importance for breeding seabirds highlight the need to understand the impacts of these structures. Using an energetic modelling approach, we examine the effects of wind farms as barriers to movement on seabirds of differing morphology. Additional costs, expressed in relation to typical daily energetic expenditures, were highest per unit flight for seabirds with high wing loadings, such as cormorants.
Impact of terrestrial wind farms on diurnal raptors: Developing a spatial vulnerability index and potential vulnerability maps
Ardeola 57(1), 2010, 41-53
José C. Noguera, Dpto. Ecoloxíae Bioloxía Animal, Edificio de Ciencias Experimentales, Universidad de Vigo (Pontevedra), Spain
Irene Pérez, División de Ecología, Dpto. de Biología Alicada, Universidad Miguel Hernández, Elche (Alicante),Spain
Eduardo Mínguez, Parque Natural Serra Gelada y su Entorno Litoral, Benidorm (Alicante), Spain
Using an RSI [raptor sensitivity index] and relative habitat use estimation, an SVI [spatial vulnerability index] was calculated and a potential vulnerability map was produced for the Boquerón mountain range in the Valencia region. Golden eagle Aquila chrysaetos, short-toed eagle Circaetus gallicus and booted eagle Hieraaetus pennatus, together with other species such as griffon vulture Gyps fulvus were the more sensitive species to wind farm. The SVI distinguished zones in which either the elimination or change of position of turbines might reduce the impact of future wind farms.
Impacto de campos eólicos terrestres sobre rapaces diurnas: Desarrollo de un índice de vulnerabilidad espacial y mapas de vulnerabilidad potencial
Mediante el empleo del RSI [sensibilidad para aves rapaces] y la estimación del uso relativo del hábitat, se calculo el SVI [vulnerabilidad espacial] y se construyó un mapa de vulnerabilidad potencial para la sierra del Boquerón, en la provincia de Valencia. El águila real Aquila chrysaetos, culebrera europea Circaetus gallicus y aguililla calzada Hieraaetus pennatus, junto con otras especies como el buitre leonado Gyps fulvus, fueron las especies mas sensibles frente a la futura instalación de campos eólicos. El SVI distinguió zonas en las que tanto la eliminación como el cambio de posición de turbinas podrían reducir el impacto de los futuros parques eólicos.
What is the impact of wind farms on birds? A case study in southern Spain
Biodiversity and Conservation. Published online: 05 July 2009. doi:10.1007/s10531-009-9677-4
M.A. Farfán, J.M. Vargas, Biogea Consultores, Málaga, Spain
J. Duarte, R. Real, Departamento de Biología Animal, Facultad de Ciencias, Universidad de Málaga, Spain
Wind farms represent a new source of impact and disturbance for birds that adds to the long list of disturbance factors caused by human activity, such as power lines, radio and television towers, highways, glass windows, the practice of poisoning, illegal hunting and overexploitation. Due to the precarious situation of several bird species and their decline, any additional cause of mortality may be significant and should give rise to increased attention and research. The aim of the present work is to analyse the effect of the “Sierra de Aguas” wind farm on bird density and abundance, flight behaviour, and bird mortality. Mortality rates did not increase due to the presence of the wind turbines. However, raptors used the space around the wind farm with lower frequency than prior to its existence, which represented a displacement of the home range of these species.
Barriers to movement: Impacts of wind farms on migrating birds
ICES Journal of Marine Science, 66: 746–753 (2009)
Elizabeth A. Masden, Daniel T. Haydon, and Robert W. Furness, Department of Ecology and Evolutionary Biology, University of Glasgow, Scotland, UK
Anthony D. Fox and Mark Desholm, Department of Wildlife Ecology and Biodiversity, National Environmental Research Institute, University of Aarhus, Rønde, Denmark
Rhys Bullman, Scottish Natural Heritage, The Beta Centre, Innovation Park, University of Stirling, Scotland, UK
Wind farms, both operational and in planning, can be expected to impact negatively on wildlife populations, particularly birds. We propose a novel approach to assess the impacts through the energetic costs of avoidance behaviour for a long-distance, migratory seaduck. Flight trajectories were recorded using surveillance radar at a Danish offshore wind farm with emphasis placed on the 200 000+ migrating common eiders that pass through the area annually. Minimum distance to wind farm and curvature of trajectories were compared pre- and post-construction. Additional costs of the avoidance response were estimated using an avian energetic model. The curvature of eider trajectories was greatest post-construction and within 500 m of the wind farm, with a median curvature significantly greater than pre-construction, suggesting that the birds adjusted their flight paths in the presence of the wind farm. Additional distance travelled as a consequence of the wind farm’s presence was ca. 500 m and trivial compared with the total costs of a migration episode of 1400 km. However, construction of further wind farms along the migration route could have cumulative effects on the population, especially when considered in combination with other human actions.
Poor evidence-base for assessment of windfarm impacts on birds
Environmental Conservation 34 (1): 1–11 (2007). doi:10.1017/S0376892907003554
Gavin B. Stewart, Andrew S. Pullin and Christopher F. Coles
Centre for Evidence-Based Conservation, School of Biosciences, University of Birmingham, Edgbaston, UK
A concern raised against widespread windfarm development is that it may negatively impact bird populations as a result of bird collision with turbines, habitat loss and disturbance. Although the synthesized data suggest a significant negative impact of windfarms on bird abundance, there is considerable variation in the impact of individual windfarm sites on individual bird species, and it is unclear if the negative impact is a decline in population abundance or a decline in use owing to avoidance. Anseriformes experienced greater declines in abundance than other taxa, followed by Charadriiformes, Falconiformes and Accipitriformes, and Passeriformes. Time since windfarms commenced operation also had a significant impact on bird abundance, with longer operating times resulting in greater declines in abundance than short operating times. Other variables, including turbine number and turbine power either had very weak but statistically significant effects or did not have a significant effect on bird abundance. Windfarms may have significant biological impacts, especially over longer time scales, but the evidence-base is poor, with many studies being methodologically weak, and more long-term impact assessments are required. There is clear evidence that Anseriformes (wildfowl) and Charadriiformes (waders) experience declines in abundance, suggesting that a precautionary approach should be adopted to windfarm development near aggregations of these taxa in offshore and coastal locations.
See also:
- Effects of wind-energy facilities on breeding grassland bird distributions
- Understanding bird collisions at wind farms: An updated review on the causes and possible mitigation strategies
- An analysis of displacement from wind turbines in a wintering grassland bird community
- Visual fields, foraging and collision vulnerability in Gyps vultures
- Distribution of breeding birds around upland wind farms
- Behavioural and environmental correlates of soaring-bird mortality at on-shore wind turbines