A study carried out by UK bird charities has found that many bird species are unaffected by wind farms. Scientists with the British Trust for Ornithology (BTO) and RSPB concluded that building the turbines was more disruptive than operating them. The impact of wind farms varied between species, with red grouse numbers recovering after construction, curlews declining and not recovering, and skylarks increasing. The findings were published in the Journal of Applied Ecology. The study is the latest in a series of reports on wind farms\' interactions with birds, but differs from most in its scale. Ten species of birds were included, and 18 wind farms in upland areas of the UK were studied. Most were monitored before construction began, during construction, and again afterwards. \"There\'s certainly no indication in the species we covered in this study that collision mortality is causing a big problem, but we need to bear in mind that it didn\'t cover the bigger raptors where we know collisions tend to happen,\" said Jeremy Wilson, head of science at RSPB Scotland to the British Broadcasting Corporation (BBC). \"Where we are concerned is with two species, curlew and snipe, where we saw the density drop during construction and not recover afterwards. \"The overall picture is perhaps more positive than some of the wilder headlines have suggested; but that doesn\'t suggest there\'s no problem.\" Curlews, which have seen declines of 30-90 percent in different parts of the UK in the last couple of decades, are known to be sensitive to human disturbance. In the UK, they declined in density by about a third during wind farm construction, as did snipe, without recovering. Red grouse showed a similar decline during construction, but numbers rose again directly afterwards. Skylark numbers soared as the turbines neared completion, and remained elevated after building finished - perhaps because turning over the vegetation helps them nest or find food. Lapwings, golden plovers and dunlins showed little change. The study is unlikely to change the charities\' existing approach to onshore wind farms, which is generally to favour development because of the damage that climate change threatens to bring to wildlife worldwide, but to oppose it in areas where birds are likely to suffer.