Are breeding Eurasian curlew Numenius arquata displaced by wind energy developments?

Are breeding Eurasian curlew Numenius arquata displaced by wind energy developments?

Summary: In 2009 a paper by Pearce-Higgins et al (see previous BSG news and resources bulletin) concluded that operational wind farms had resulted in the displacement of a number of upland breeding bird species.  Since this time, nature conservation consultees have become concerned about displacement effects and the impacts this might have on wader populations.  Curlew, a species identified in the paper as showing a reduction in nesting density at distances of up to 800m from turbines, has been a particular concern, especially in areas (such as upland Wales) where local populations have been subject to considerable declines and are already extremely fragmented.  This has led to requests for large-scale ‘compensatory’ off site habitat management in relation to some wind farm planning applications.

Over the past few years information from monitoring and research projects has begun to emerge that brings into question the results of the paper by Pearce-Higgins et al.  We have already summarised a paper from Beinn Tharsuinn wind farm that appears to show no displacement effects for golden plover, one of the species cited in the paper (see previous BSG news and resources bulletin).  Until relatively recently, however, the public domain evidence available to question the conclusions of the study with regard to curlew was relatively limited, and had to be pieced together from a variety of sources (many of which were anecdotal).

In August 2010, Natural Research published a detailed study on curlew at operational wind farm sites.  Survey work was undertaken at five operational wind farms and in two reference areas.  The study investigated whether there was any evidence of an immediate displacement effect following construction, whether the effect was more gradual (i.e. numbers declined over several breeding seasons) and whether there was evidence of decreased nesting success close to operational turbines.

The study concluded that there was no correlation between proximity of breeding site to a turbine and nesting success.  There was no evidence of immediate displacement of curlew at four of the wind farm sites, and inconclusive results at the fifth.  No clear evidence of gradual displacement was collected, and at one wind farm curlew territories moved closer to turbine arrays over four years of operation.

The Natural Research study showed very little evidence of displacement of curlew by operational wind farms, and its results indicated that curlew was not a sensitive species in this regard.  The authors also noted that due to the overlap between their sites and the Pearce-Higgins sites, the results of the two studies appeared incompatible.  This was put down to a technicality in the interpretation of the curlew data in the Pearce-Higgins paper, and the authors concluded that there is no research at UK wind farms that provides robust evidence for displacement effects on breeding curlew.

Viewpoint: There is a growing body of evidence that suggests that wind farm developments do not result in the degree of displacement suggested by Pearce Higgins et al (2009), and that they may in fact have relatively little effect on the distribution of most upland breeding birds.  The paper on displacement of curlew by Natural Research, a recent study by Fielding and Haworth (2010) on golden plover at the Farr Wind Farm and monitoring undertaken at Beinn Tharsuinn Wind Farm all present a different slant on the question of upland bird impacts that should not be ignored. These are all credible papers, reaching reasoned conclusions based on detailed survey work.  This body of information should promote a better understanding among wind farm developers and other stakeholders of what is proportional in terms of ‘compensatory’ land management. It should also provide an incentive to release the results of monitoring studies into the public domain.

Read BSG’s technical review here: Are Curlew Displaced by Wind Energy Developments

Photograph kindly supplied by Artur Stankiewicz.  © Artur Stankiewicz


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