AUTHOR=Trinder Mark , O’Brien Susan H. , Deimel Joseph 

TITLE=A new method for quantifying redistribution of seabirds within operational offshore wind farms finds no evidence of within-wind farm displacement

JOURNAL=Frontiers in Marine Science

VOLUME=Volume 11 - 2024

YEAR=2024

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2024.1235061

DOI=10.3389/fmars.2024.1235061

ISSN=2296-7745

ABSTRACT=The climate crisis is driving a rapid increase in size and number of offshore wind farms to reduce carbon emissions from electricity generation. However, there are concerns about the potential impact of offshore wind farms on the marine environment. Seabirds are considered to be at risk of being displaced from preferred foraging habitat, by construction and operation of offshore wind farms. Seabird distributions are highly variable through time and space so discerning changes in distribution caused by an offshore wind farm from other environmental variables is challenging. We present a new method that controls for temporal variation by examining the location of individual seabirds relative to turbines. Mean seabird densities at different distances from individual turbines (0-400m) were calculated from data collected on a total of 12 digital aerial surveys of the Beatrice Offshore Wind Farm (UK), in May-August in 2019 and 2021. The mean densities of common guillemot (Uria aalge), razorbill (Alca torda), Atlantic puffin (Fratercula arctica) and black-legged kittiwake (Rissa tridactyla) did not differ significantly from those expected by chance (i.e. no displacement effect was detected). There was a slight tendency for guillemot and razorbill, when sat on the water, to be at higher densities  near turbines than expected, suggestive of possible attraction to turbines, while flying birds tended to be at lower densities near turbines than expected, suggestive of possible avoidance. Kittiwake tended to show neither avoidance nor attraction to turbines. Puffins sat on the water were recorded in densities similar to those expected. Overall, no effect of turbine rotor speed was found, with birds no more likely to avoid turbines operating at higher rotor speeds. The results of the turbine relocation analysis gave a more consistent and more easily interpreted assessment of displacement/avoidance behaviour than the typical approaches of comparing abundance and seabird distribution through time (e.g. before-after studies). We strongly encourage application of this new approach to post-construction spatial distribution data from other offshore wind farms, to build the evidence base on the effects of offshore wind farms on seabirds.