Scottish Marine and Freshwater Science Volume 5 Number 13: Population consequences of displacement from proposed offshore wind energy developments for seabirds breeding at Scottish SPAs

1 Project scope

Offshore wind developments have the potential to impact on the daily energy and time budgets of seabirds by displacing birds from habitats that are essential for key life history behaviours such as foraging, maintenance and courtship (Larsen & Guillemette 2007). There is particular concern that wind farm developments which are located on favoured foraging habitats may force birds to forage at greater densities in suboptimal habitats. The impact of displacement is predicted to be particularly important for breeding seabirds that, as central place foragers, are constrained to obtain their food within a certain distance of the breeding colony (Daunt et al. 2002; Enstipp et al 2006). Changes in time and energy budgets resulting from displacement from renewable energy developments have the potential to impact on the body condition, and hence survival prospects, of breeding adults. Such changes may also reduce breeding success if provisioning rate declines result in offspring starvation, or if the extended time required for foraging results in temporary unattendance of eggs or young, which increases the likelihood of mortality from predation or exposure.

The best current evidence on displacement is for non-breeding individuals available from wind farm developments outside the UK, and results have been inconsistent with varying levels of displacement behaviour recorded among locations and species (Petersen et al. 2006, 2011; Fox et al 2006; Leopold et al. 2011; Vanerman et al. 2011, 2012; Leonhard et al. 2013). Furthermore, there is a paucity of information on the behaviour of breeding seabirds in response to wind farms, yet there is expected to be greater constraints on breeding individuals. In recognition of these substantial uncertainties and important knowledge gaps, Marine Scotland have commissioned this project with the aim of developing time and energy expenditure models to estimate population consequences of displacement from proposed offshore wind energy developments for key species of seabirds breeding at Scottish SPAs and to apply these models to the Forth/Tay offshore wind farm development area.

The steering group identified five seabird species for which displacement modelling was required in support of HRA/ AA for Forth/Tay developments:

• black-legged kittiwakes Rissa tridactyla
• common guillemot Uria aalge
• razorbill Alca torda
• Atlantic puffin Fratercula arctica
• northern gannet Morus bassanus

The steering group agreed that the following SPAs close to the Forth/Tay region should be considered in this report:

• Buchan Ness to Collieston Coast SPA
• Fowsheugh SPA
• Forth Islands SPA
• St Abb's Head to Fastcastle SPA

The group also agreed that four proposed wind farms should be considered:

• Neart na Goithe
• Inch Cape
• Round 3 Alpha
• Round 3 Bravo

and that cumulative effects of all four wind farms should also be estimated. A map of the study area can be found in Figure 1:1.

The project involved initially running a set of exploratory simulations on all species except gannet (because of time constraints and because this species was of least concern) in which a large number of scenarios were considered but a small sample of birds was used in order to prevent the computational cost becoming probative. These exploratory results were used to derive a smaller number of scenarios of greatest interest, and simulations from these scenarios using much larger samples of birds were then used to generate the final results.

Figure 1:1: Map of study area showing SPAs and proposed wind farms.