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| European legislation requires Strategic Environmental Assessments (SEAs) of national offshore
wind farm (OWF) programmes and Environmental Impact Assessments (EIAs) for individual
projects likely to affect birds. SEAs require extensive mapping of waterbird densities to
define breeding and feeding areas of importance and sensitivity. Use of extensive large scale
weather, military, and air traffic control surveillance radar is recommended, to define areas,
routes and behaviour of migrating birds, and to determine avian migration corridors in three
dimensions. EIAs for individual OWFs should define the key avian species present; as well
as assess the hazards presented to birds in terms of avoidance behaviour, habitat change and
collision risk. Such measures, however, are less helpful in assessing cumulative impacts.
Using aerial survey, physical habitat loss, modification, or gain and effective habitat loss
through avoidance behaviour can be measured using bird densities as a proxy measure of
habitat availability. The energetic consequences of avoidance responses and habitat change
should be modelled to estimate fitness costs and predict impacts at the population level. Our
present ability to model collision risk remains poor due to lack of data on species-specific
avoidance responses. There is therefore an urgent need to gather data on avoidance responses;
energetic consequences of habitat modification and avoidance flights and demographic
sensitivity of key species, most affected by OWFs. This analysis stresses the importance of
common data collection protocols, sharing of information and experience, and accessibility
of results at the international level to better improve our predictive abilities. | |
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