ORJIP Bird Collision and Avoidance Study


Title: ORJIP Bird Collision and Avoidance Study
Publication Date:
April 01, 2018
Pages: 248
Sponsoring Organization:

Document Access

Website: External Link
Attachment: Access File
(22 MB)


Skov, H.; Heinänen, S.; Norman, T.; Ward, R.; Méndez-Roldán, S.; Ellis, I. (2018). ORJIP Bird Collision and Avoidance Study. Report by Offshore Renewables Joint Industry Programme (ORJIP). pp 248.

The ORJIP BCA study, 2014 - 2017, has been designed to improve the evidence base for seabird avoidance behaviour and collisions around offshore wind farms, with the aim of informing impact assessment and supporting consenting applications for the offshore wind industry.


Driven by ambitious renewable energy targets and reduced costs, the offshore wind industry has experienced a significant growth over the last 20 years, particularly in Europe, where the majority of installed capacity can be found.


The consenting process of offshore wind projects requires the identification, prediction and evaluation of the environmental effects of those proposed projects. In this context, the risk of birds colliding with turbine blades during operation is potentially one of the most significant environmental impacts predicted. In order to quantify bird collision risk, collision risk models (CRM) are used and parametrised with technical specifications of the turbines, bird densities, morphology and flight behaviour of existing bird populations present on site. The CRM e.g. the Band model (Band 2012), provides an estimate of the potential number of bird collisions likely to occur at a proposed wind farm assuming that birds take no action to avoid colliding with the wind turbines. In order to obtain realistic risk estimates, the collision risk modelling is subsequently corrected to take account of behavioural responses of birds to the presence of wind farms (i.e. avoidance). However, there is considerable uncertainty over the scale of such impacts due to the relatively few offshore monitoring studies so far undertaken, that have gathered empirical evidence.


As the number of offshore wind farm projects increases, it is widely recognised that in order to minimise consenting risks for future project applications, further robust evidence on the avoidance behaviour of seabirds is required to inform CRM and environmental impact assessments.


This study has centred its work around four main phases:

  1. Development of a bird monitoring system, that allows detecting and tracking bird movements at the species level in and around an operational offshore wind farm, including testing and validation of video monitoring coupled with radar technology under different weather and visibility conditions.
  2. Monitoring of bird behaviour at Thanet Offshore Wind Farm, deploying a multiple sensor monitoring system partly operated by experienced seabird observers (laser rangefinders and radar equipment), and partly automated through the collection of video evidence, with a focus on five target species: Northern Gannet, Black-legged Kittiwake and three species of large gulls (Lesser Black-backed Gull, Herring Gull, Great Black-backed Gull).
  3. Development of an appropriate methodology for data analysis to quantify empirical avoidance behaviour termed as empirical avoidance rates (EARs), based on existing research and equipment / data limitations.
  4. Formulation of recommendations on the use of empirical evidence gathered by this study in support of collision risk assessments in offshore wind planning applications.

This report presents the final publication of the study and presents findings associated with these four phases.

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