New research led by Aonghais Cook of the BTO has tested a variety of analytical tools, or models, to assess the likely population-level consequences of the impacts arising from any individual wind farm development. These include tools predicting the likelihood of a given outcome (e.g. the probability of a 25% decline) and those that compare scenarios with and without the development. The results demonstrate that conclusions about the significance of any population-level consequences differ according to the initial assumptions made about a seabird species’ survival, breeding success and population trend. The effect of these assumptions is particularly noticeable for approaches that predict the likelihood of a given outcome. In a world where our knowledge of wildlife populations is often imperfect, this may lead to situations where conclusions about the significance of any population-level impacts are driven by how knowledgeable we are about the population concerned, rather than by the magnitude of any impact.

This research suggests that future assessments should compare the outputs of models considering scenarios for wildlife with and without any wind farm development. However, given that our knowledge of the population concerned can influence our conclusions, it is important that all assumptions used in the modelling are clearly stated. Judgement of whether any population-level consequences can be deemed acceptable should then be made with reference to our knowledge of the species concerned and its local, regional, national and international populations, ensuring that decisions about offshore wind farm development are made in the best possible way for wildlife.

Part of this work was funded by the Joint Nature Conservation Committee, Natural England and Scottish Natural Heritage. The remainder was funded by the British Trust for Ornithology.