The value of seabird foraging ranges as a tool to investigate potential interactions with offshore wind farms

One of the key emerging pressures facing seabird populations is the development of offshore wind farms (OWFs). Estimates of seabird foraging ranges have been widely used to assess the potential of birds from specific colonies to interact with planned OWFs, and to apportion any predicted impacts to breeding populations. Ideally, these foraging range data would be site-specific estimates, collected from the colonies of interest using tracking devices within a timeframe of relevance to the planning process. However, logistical constraints linked to site accessibility, the availability of tags and suitably trained personnel to deploy them and the need to avoid deleterious tag effects mean that this is not always possible. Consequently, many assessments rely on previously published estimates of seabird foraging ranges. The rapid development of tracking technology means that there has been a substantial increase in both the number of individual birds and the number of seabird breeding colonies from which tracking data originate, increasing uncertainty as to whether assessments are based on the best available evidence. To address this, we carried out a systematic literature review of tracking studies for 27 species. By accounting for recently published data, we are able to generate more robust estimates of foraging ranges for many of these species. In some cases, these were more than double previous estimates. We investigate the potential for birds to interact with 41 new wind farms planned for UK waters. Whilst the collection of site-specific data to inform assessments for future OWFs is desirable, generic values, such as those presented here, are likely to play an important role for the foreseeable future. We discuss the limitations and issues to consider when using generic foraging ranges, and highlight the importance of having access to consolidated up-to-date information within the decision-making process.