Seabirds: strategic ornithological compensatory measures: review

2 Introduction

The Scottish Government has set out goals to reduce carbon emissions across the Scottish economy over the coming decades, with a net zero emissions target by 2045. A key part of the Government’s strategy for decarbonising the economy is by supporting the development of sustainable offshore energy production. In the medium term it is anticipated that as much as 11 GW of offshore wind farm (OWF) capacity could be delivered by 2030 (Scottish Government, 2020b), which would also contribute towards the UK Government’s target of 50 GW of total installed capacity by 2030 (outlined in the British Energy Security Strategy) (UK Government, 2022). The ScotWind leasing round led to lease option agreements for 20 potential OWFs (17 in the initial announcement in January 2022 and a further three sites announced in August 2022) totalling a potential capacity of 27.6 GW. A further 13 OWFs with a total potential capacity of 5.5 GW have been offered initial agreements for leases by Crown Estate Scotland (Crown Estate Scotland, 2023) under the Sectoral Marine Plan for Innovation and Targeted Oil and Gas (INTOG) Decarbonisation (Scottish Government, 2022b).

The Habitats Regulation Appraisal (HRA) for the Sectoral Marine Plan for Offshore Wind Energy, which underpins the ScotWind leasing round, was unable to conclude that there would be No Adverse Effect on Site Integrity (NAEOSI). This uncertainty stems from the current understanding around the potential scale of in combination impacts on protected seabird populations (i.e. those originating from Special Protection Areas; SPAs) and the need for precaution given the level of uncertainty on the scale of impact (Scottish Government, 2019). The plan-level Appropriate Assessment was able to conclude NAEOSI, but only with a number of mitigation measures applied, including the need for project-level HRA. The plan is currently undergoing a review as part of the iterative plan review process, which includes the consideration of outcomes from the ScotWind and INTOG leasing rounds.

It is now anticipated that it is likely that it will not be possible to conclude NAEOSI for some future OWFs in Scottish Waters, and thus, if these developments are to proceed, it would be following the derogation procedure under Article 6(4) of the Habitats Directive. This process has already been implemented for proposed OWFs in English Waters, with Hornsea Project Three and Norfolk Boreas being the first developments to follow this approach. For a development to be consented with a derogation under Article 6(4), three sequential legal tests must be met, the third of which is whether necessary compensatory measures can be secured to offset the assessed impacts for the proposed development.

This third test requires that Scottish Ministers (or the Secretary of State, depending on the applicable legislation) ensure that any necessary compensatory measures are taken for the protection of the overall coherence of the UK site network (NatureScot, 2024). The general principles to be considered are outlined in the European Commission guidance (European Commission, 2021) (which are transposed into UK guidance (DEFRA, 2021)):

• that compensatory measures deliver for the ecological functions affected by the plan or project;
• that measures are put into place, are fully operational and effective before the damage occurs;
• that the delivery of effective compensation should be verified through adequate monitoring.

To have confidence of these, it is necessary to demonstrate the ecological feasibility of proposed measures which, when simplified, equates to providing a conservation benefit to the impacted SPA feature species that ideally outweighs the assessed impact. Ensuring that appropriate compensatory measures can be put into place ahead of the proposed impact requires confidence in the feasibility of the technical, legal, and financial provisions for implementation. Once measures are put into place then there is a requirement to demonstrate that they are indeed delivering the intended benefit through monitoring.

Compensatory measures for seabirds are some forms of activity or management intervention which may offset the impacts to protected seabirds of one or more OWFs. The term ‘compensatory measure’ is a broad term which could include e.g. a suite of coordinated actions, but must be measures that deliver a compensatory response, i.e. counteracting a given population level impact. For this report we use a more specific term ‘conservation action’ when considering candidate options that if assessed to be suitable could be implemented as compensatory measures. This distinction follows international conservation terminology (Salafsky et al., 2008), conservation actions denoting specific management interventions undertaken with the aim of delivering a gain and/or recovery of a habitat or population. Consequently, conservation actions have potential to be used as compensatory measures subject to meeting various tests, both relating to efficacy and other factors such as additionality. Because compensatory measures can be used as a more general term referring to either a single or a potential suite or category of conservation actions, hereafter, we will refer to a conservation action when referring to a specific management effort.

As such, considering compensation options for seabirds starts with understanding threats and pressures acting on seabird populations and the potential conservation actions to either reduce existing pressures on populations (e.g. fisheries bycatch reduction) or by improving existing conditions in some way (e.g. restoration of habitat). The primary threats and most beneficial conservation actions for seabird populations are relatively well understood (for recent reviews see Dias et al. (2019), Johnston et al. (2021), and Young and VanderWerf (2023)), however understanding which conservation actions may be effective compensatory measures, and for which specific colonies, populations, or species, is less straightforward.

To date, compensatory measures for OWFs have occurred on a project-by-project basis, however it is recognised that at least, in some instances, compensatory measures may be best delivered strategically (e.g. see reforms progressed as part of the Offshore Wind Environmental Improvement Package in the UK Energy Act). This is termed ‘strategic compensation’ (see Glossary and common acronyms for definition of this and other terms). By delivering compensation strategically, the impacts of multiple OWFs (e.g. those under the same sectoral marine plan) can be effectively compensated through coordinated and larger scale conservation actions which may provide greater conservation benefits by fitting with the large spatial scales that seabirds operate at (Oppel et al., 2018). Strategic delivery, usually involving government bodies, also allows for certain types of conservation actions to be delivered that are not in the control of developers (e.g. those requiring a government policy or regulatory response to implement). The purpose of this project is to improve the evidence base around potential strategic compensatory measures for seabird populations. Strategic compensatory measures are here defined broadly to be any compensatory measures that apply to at least two OWFs or are delivered at plan-level.

In the past few years there have been several studies reviewing potential compensatory measures in in the context of Britain and Ireland, both for impacts from OWF and from climate change, e.g. Furness (2021), Pearce-Higgins et al. (2021), and McGregor et al. (2022). However, there remains considerable uncertainty around the feasibility of many of these compensatory measures, both in terms of whether they would be effective (i.e. by delivering meaningful scales of compensation) and in the practicality of implementing them. This project is focussed on better understanding the feasibility of compensatory measures for seabirds in a Scottish context.

2.1 Structure and approach to project

The project is structured into two work packages (WP), which together look at the overall feasibility of a list of compensatory measures collated by the Marine Directorate (Table 4). The first WP evaluates ecological feasibility (WP1) while the second evaluates practical feasibility (WP2). Each WP is sub-divided into several linked component steps (Figure 2).

2.1.1 Ecological feasibility (WP1)

The objective of the first WP (WP1) was to assess the ecological feasibility of the candidate compensatory measures (Table 4). Here, we define ecological feasibility as a combination of the likelihood that a measure is beneficial, i.e. bringing about a population-level benefit to the target seabird species (e.g. an increase in productivity or survival) and the size of effect found across studies (for details see section 3.1.2.2 below).

Some of the proposed compensatory measures (as described in Table 4) correspond directly to a single conservation action (i.e. management intervention). Others represent a suite of possible conservation actions, or their associated conservation actions are undefined or unclear. Therefore, we first identified the conservation actions associated with each compensatory measure. For those measures where conservation actions were clear, we conducted one or more systematic literature reviews (see section 3.1.1) to find, collate and analyse relevant evidence. We then used a qualitative approach to assess their ecological feasibility. This involved assigning scores to each measure on a common continuous scale, enabling the comparison of their relative ecological feasibility (i.e. not just a binary outcome). We also estimated our level of confidence in these scores.

In cases where compensatory measures were broader and unclear, representing a suite of potential conservation actions (defined or undefined), we conducted a scoping review to identify the conservation actions that are likely to provide the most benefit. Additionally, we undertook a targeted review on bycatch mitigation with the aim of summarising the key findings of a recent review to put this in the context of strategic compensation.

Table 4. The original list of compensatory measures collated by Scottish Government, and the associated seabird species that each measure may benefit. Focal species are highlighted in bold, and measures are numbered for convenience. It was also noted that synergies across compensatory measures and delivery may also be considered. The table footnotes are retained (edited) from the original table.

This table can be viewed in Excel format.

2.1.2 Practical feasibility (WP2)

The objective of the second WP (WP2) was to assess the practical feasibility of those conservation actions that were most ecologically feasible. For each conservation action, an implementation plan was developed, outlining the necessary steps required to put an action in place. This section also evaluates the scale and degree of benefit of each action on focal species and other possible benefitting species. Additionally, it provides recommendations for required monitoring efforts to assess progress and the ultimate success of the conservation action and lists potential issues and possible solutions that must be considered prior to implementation.

In this section we also drew on wider RSPB expertise^[1] in practical conservation, asking relevant staff (e.g. site managers, scientists, engagement officers) to provide recommendations and comments on the drafts of the practical feasibility chapters. This allowed us to draw on real world examples where conservation actions have previously been implemented and to use expert assessment on whether it could prove effective on focal species. RSPB policy and planning colleagues were also contacted to gain insights into potential technical, political, or legal barriers.