Author: | Wildlife
1. Birds most at risk from wind turbines have been shown to be birds of prey and waterfowl. Passerines are at slightly lesser risk but are still impacted.
References: Desholm, M. 2009, Journal of Environmental Management, 90, 2672-2679; Madson & Boertman, 2008, Landscape Ecology, 23, 1007-1011
2. It is not just a simple matter of wind turbines killing birds by collisions because they migrate across the site or nest close to developments. What also matters is the presence of turbines, especially in arrays, located between the roosting, nesting or foraging sites of birds because the turbines form a ‘barrier’ the birds cannot or will not cross.
Reference: Ferrer et al., 2012. Journal of Applied Ecology, 49, 38-46.
3. Flying over or diverting around wind farms to reach foraging or roosting sites has high energy costs for birds, as the higher or further they fly the greater metabolic demand this imposes on them. This can be critical during the winter when food is scarce and the air temperature is low.
Reference: Sugimoto et al., 2011. Ornithological Science, 10, 61-71.
4. Grassland birds, such as lapwing that forage on the ground, are mainly impacted by turbines because the turbines prevent or deter their movement between forage and roost sites.
Reference: Pruett, et al., 2009. Bioscience, 59, 257-262.
5. An 11-year study of bird mortality in relation to wind farm developments at coastal regions in Northumbria found that between 16 and 21 birds were killed per turbine per year, mainly by collision. Affected species tended to be guillemots, kittiwakes, gulls and pigeons.
Reference: Newton & Little, 2009, Bird Studies, 56, 158-167.
6. Mortality of raptors from turbines has been found not to correlate with bird abundance. Rather mortality depends on turbine height and elevation above sea level. The taller or higher the turbine the greater the mortality rate.
Reference: De Lucas et al., 2008. Journal of Applied Ecology, 45, 1695-1703.
7. Male birds tend to be killed more frequently by turbines than females because they spend more time foraging. However, chicks suffer and may die indirectly because they depend on food foraged by males to supplement that obtained by females.
Reference: Stienen et al., 2008. Condor, 110, 154-157.
8. Some wildlife species, including birds and squirrels, have been shown to suffer stress (as indicated by high alertness behaviour and alarm calling) in the vicinity of wind turbines compared to animals under control (no turbine) conditions. It is well known that prolonged (chronic) exposure to stress reduces fecundity, immunity, growth and longevity in many animal species.
Reference: Kikuchi, 2008. Journal for Nature Conservation, 16, 44-55.
9. Poor correlation exists between pre–wind farm development risk assessments and actual post construction recorded deaths. Deaths are often underestimated because carcases attract scavenging birds. These, in turn, are then struck by the blades and die, thus pushing up the overall death count.
Reference: Smallwood et al., 2010. Journal of Wildlife Management, 74, 1089-1097.
10. Assessment of bird or bat mortality by counting carcases is also unreliable if other scavengers (eg foxes) remove corpses from the area, especially at night, before counting is undertaken. Therefore recorded mortality rates due to collision are probably less than the real death toll.
Reference: Korner-Nievergelt et al., 2011, Wildlife Biology, 17, 350-363.
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