1. SNH and the BWEA have prepared draft guidance (Scottish Natural Heritage 2000a, b) on assessing the impacts of a wind farm on ornithological interests, which outlines the three potential risks which wind farms present to birds:
(i) displacement through indirect loss of habitat if birds avoid the wind farm area and its surrounding area due to turbine operation and maintenance/ visitor disturbance. Displacement can include barrier effects in which birds are deterred from using normal routes to feeing or roosting grounds;
(ii) death through collision or interaction with turbine blades;
(iii) direct habitat loss through construction of wind farm infrastructure.
An assessment of a potential wind farm's effect on the bird interest of a site should thoroughly consider each of these three potential risks for each bird species which uses the site.
2. For each of these three risks, knowledge of bird distribution and activity is necessary in order to quantify the risk. The purpose of this guidance is to advise on the field survey methods which should be used to enable these risks to be assessed.
3. This guidance is written for developers and their ecological consultants, and also for SNH Area staff and those within the consenting authorities who are required to consider documents relating to ornithology submitted as part of a wind farm application.