Wind farm consequences

WITH climate change and population growth, a global energy crisis looms.

Alternative sources of power must be developed, fast. Harnessing waves and tidal flows is difficult. Roof panels have a role but solar energy on a large scale may only be possible in sunnier climes.

Wind farms have their critics but the windmill is the most promising alternative technology. Ireland is one of the windiest countries; if this resource can be tapped successfully, it’s here. In 2020, forecasts suggest, 20% of Europe’s energy will come from wind. This will increase to 30% by 2030. Estimates for the use of wind energy worldwide vary from 5% to 29%. Turbines can be located at sea but land ones make more economic sense. Inevitably, wind farms will be a feature of upland everywhere.

This is a clean, relatively pollution-free, source of energy. There is a downside. Output depends on wind levels and these fluctuate unpredictably. Turbines are noisy. Located where the wind is strongest, they tend to be visually intrusive. They also threaten birds. “Some birds are particularly sensitive to wind-farm development, largely due to collisions or disturbance displacement,” said American researchers Drewitt and Langston in a recent paper.

But quantifying mortality and the extent of disruption to birds is difficult. Are some species more vulnerable than others? Are migrants wandering into an area more at risk than residents? Do waders grouse and small songbirds suffer equally when sharing their habitat with windmills? The Royal Society for the Protection of Birds and Scottish Nature decided to find out. The results of research commissioned by them appears in the current issue of the Journal of Applied Ecology. There are findings which might favour each side of the wind farm debate.

With the number of planning applications increasing, the paper by James Pearce-Higgins, Leigh Stephen, Andy Douse and Rowena Langston will, no doubt, be quoted at oral hearings here.

Beginning in 2007, the researchers monitored bird numbers at 18 upland locations in Scotland and England. Sites with windmills were compared with similar ones without them. Each wind farm had at least five turbines. The research focused on ten bird species. “Some poorly-sited wind farms have resulted in sufficient deaths to have at least a local population-level effect on raptors,” say the authors.

However, birds of prey are thin on the ground; sample sizes weren’t big enough for them to be included in the research. Three wader species, curlew snipe and golden plover, featured.

The scientists sought to answer three questions. How detrimental to birds are wind farms during the construction phase? What problems arise when the mills start turning? Are the size of turbines, their spacing or the overall power output of a wind farm, important?

The results were intriguing. In general, the greatest impacts on birds were felt during the construction, rather than in the operational, phase of a farm. The effects on some breeding waders were particularly severe. The numbers of curlew and snipe fell when construction began and they failed to recover when building had ceased. Red grouse left the vicinity when windmills were being installed but returned within a year of the wind farms becoming operational.

Not all species were adversely affected; the numbers of stonechats and skylarks went up while windmills were being constructed. Building work clears ground vegetation and disturbs the soil, making food items available, perhaps. The height or power of turbines does not seem to matter as far as the impact on birds is concerned.

However, the decline in curlew numbers increased with turbine density.

The authors recommend that construction of wind farms should take place outside the breeding seasons of waders such as curlew and snipe, advice which is particularly relevant to this country, given recent declines in our breeding curlew population.

* ‘Greater impacts of wind farms on bird populations during construction than subsequent operation: results of a multi-site and multi-species analysis’. Journal of Applied Ecology. Vol 49.


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