An interesting new piece of research throws fresh light on the issue of the impact of wind farms on bird populations in their vicinity. Carried out for Scottish Heritage and published in the Journal of Applied Ecology, the study is mainly focussed on 10 species of birds from upland habitats in European settings.
Its application to Australia is obviously subject to many caveats due to the different species and ecosystems. However the main finding is that mortality due to collisions with turbines is not a major factor, although some bird populations decline during construction and not all return to the same level during the operational phase.
In other words, disturbance is a much bigger factor than collision and some birds may simply choose to nest in other available habitat after a windfarm is established. The extent to which wind farms cause general population declines, which would therefore be of a wider conservation concern, has to date been largely untested.
The study used monitoring data collected by wind farms located on unenclosed upland habitats. This data was analysed to test whether breeding densities of upland birds were reduced as a result of wind farm construction or during wind farm operation and compared to reference sites.
Data was available for ten species, although none were raptors. The key impacts were on the densities of three of these species, red grouse, snipe and curlew (of these only the Eurasian Curlew is found in Australia and it is a rare visitor)
The study found that all three species declined on wind farms during construction. Red grouse densities recovered after construction, but snipe and curlew densities did not. Post-construction curlew densities on wind farms were also significantly lower than reference sites. Conversely, densities of skylark and stonechat increased on wind farms during construction.
There was little evidence for consistent post-construction population declines in any species, suggesting for the first time that wind farm construction can have greater impacts upon birds than wind farm operation.
The study also concluded these impacts were largely unaffected by technical specifications (turbine height, number or total generating power) and therefore are widely applicable.
The research includes a review of other studies of individual wind farm sites, finding evidence that some birds are particularly sensitive to wind farm developments, largely through collision with turbines or disturbance displacement. Some poorly sited wind farms have resulted in sufficient deaths to have at least a local population-level effect on raptors and seabirds.
The displacement of birds away from turbines can result in individuals abandoning otherwise suitable habitat, generally over distances of 100–200 metres, although the effects vary considerably between sites, species and season/stage of the annual cycle.
This study concludes that regulatory authorities and developers should particularly consider the likely impacts of wind farms on large waders. Greater weight should be given to the effects of construction on wildlife in impact assessments than at present. Mitigation measures during construction, including restricting construction activity to non-breeding periods, should be considered and tested as a means to reduce these negative effects.
This seems sensible advice for wind farm proponents in Australia. It is worth moving the environmental assessment discussion on from the rather empty debate about the evidence of birds being killed by collision with turbine blades to consider the broader ecological impacts – with the strong suggestion these mainly occur during construction and not during operation.
Andrew Herington is a Melbourne freelance writer.