Abstract
In order to ascertain the effects of aero-generators on breeding birds, two moorland plots in Orkney's West Mainland were censused each year between 1981 and 1989. One plot was immediately adjacent to the aero genera for site while the other acted as a control. Although the bird populations in the plots were not large enough to state categorically that the aero-generators caused no declines, their effects appear to have been minimal. The only species to have been adversely affected by the development of the site was Red-throated Diver Gavia stellata and its decline was probably the result of factors other than the operation of the aerogenerators.