(The majority of the report is in Norwegian. However, there is an abstract in English.)
The objective of the present study was to develop a decision-relevant, large-scale screening tool for areas that may be suitable for the establishment of offshore wind power plants. The surveyed area ranged from the Swedish border in the south (North Sea/Skagerrak) to the northern tip of Andøya (Norwegian Sea).
Marine wind farms are a relatively new element in European waters, and at present there have been few investigations carried out to study their short- and long-term environmental effects. While there have been several studies to identify environmental impacts of wind farms in other countries, there is currently only one such study in Norway, on the island of Smøla. So far, four mechanisms have been emphasized with regard to the impact of wind farms on birds: 1) mortality resulting from collisions with wind turbines (tower and wings), 2) avoidance due to interference from installations in operation and from the activity associated with the construction of the windfarm; 3) loss and change of habitat, through habitat degradation and fragmentation, and 4) barrier effects, which may increase the flight distance and increase the birds' energy demands.
In this report, we have chosen to use a methodology that was developed to evaluate seabird vulnerability to marine wind farms in German waters. This method provides a species-specific vulnerability index based on nine factors: flight maneuverability, flight altitude, percentage of time flying, nocturnal flight activity, sensitivity towards disturbance by ship/helicopter traffic, flexibility in habitat use, biogeographical population size, adult survival rate and conservation status. Combined with a measure of density or relative proportion of the relevant species in an area, a wind farm sensitivity index (WSI) is created. The WSI can be summed for all species found in the area at different times of the year to give a total WSI for seabirds. The existing data for seabirds in winter and in the breeding season was of sufficient quality to be used for this method. For the species where less data was available (e.g. geese, waders, white-tailed eagle and the Eurasian eagle-owl) we have chosen to illustrate potential conflicts by means of maps of the major functional areas. The results are presented in maps, where the WSI is given for 10x10 km squares.
The results of the study showed a clear difference in WSI between areas and seasons. For the seabirds it was shown that especially the large breeding colonies in Vesterålen, Røst and Runde were areas with high WSI. In Vesterålen, the gannets and some of the puffin colonies resulted in a high WSI, while on Røst auks and for Runde gannets and gulls resulted in high WSI-values. Further south it was mainly gulls and terns that caused high WSI-values on the coast of Vest- Agder and between Jæren and Karmøy. The results for the breeding season were as expected, as other studies have previously pointed to these sites as valuable areas.
There were some similarities between important localities in summer and winter, for example between Jæren and Vesterålen. But during the winter season, areas such as Lista, Nordøyerne and Gossen (Møre and Romsdal), Smøla, Froan, Ørlandet, Frost, Vikna and Vega also showed a high vulnerability. For the white-tailed sea eagle especially the islands of Smøla, Hitra and Frøya, as well as the area from Bodø to Steigen were very important. For the Eurasian eagle-owl the coast of Helgeland and the areas surrounding Karmøy in Rogaland were most important. For waders and geese the focus was on important resting and moulting sites. Such sites for geese and eiders are distributed across the study area, with the most important and largest areas being the coast of central Norway and northwards. For waders a number of important resting areas are spread over the entire study area, but with a concentration of localities along the coast of Møre and Romsdal and Rogaland, especially along the coast of Jæren.
In our study, the analysis of vulnerability is done for separate areas in relation to the presence of birds. However, in the case of extensive development of large numbers of wind farms in close proximity to one another, different and stronger responses can be expected from both individuals and populations of birds than what has until now been documented for smaller offshore wind power plants. During the future development of wind power plants, both off- and on shore, it will be important to not only consider each wind power plant in isolation, but to focus on what their total or cumulative environmental effects will be.
It should be noted that our analysis is for guidance only. It is suitable for large-scale evaluations of the vulnerability of areas. To assess the suitability of specific areas for the development of wind power plants, it is, in addition to this report, necessary to study local occurrences of birds and identify important functional areas for seabirds. The basis for the index should also be assessed and reviewed continuously, so that the latest knowledge about the effects of wind farms can be incorporated in later analysis.
Norwegian Title: Offshore vindenergianlegg - sjøfugl, havørn, hubro og vadere - En screening av potensielle konfliktområder