title: Patterns of migrating soaring migrants indicate attraction to marine wind farms.
abstract: Monitoring of bird migration at marine wind farms has a short history, and unsurprisingly most studies have focused on the potential for collisions. Risk for population impacts may exist to soaring migrants such as raptors with K-strategic life-history characteristics. Soaring migrants display strong dependence on thermals and updrafts and an affinity to land areas and islands during their migration, a behaviour that creates corridors where raptors move across narrow straits and sounds and are attracted to islands. Several migration corridors for soaring birds overlap with the development regions for marine wind farms in NW Europe. However, no empirical data have yet been available on avoidance or attraction rates and behavioural reactions of soaring migrants to marine wind farms. Based on a post-construction monitoring study, we show that all raptor species displayed a significant attraction behaviour towards a wind farm. The modified migratory behaviour was also significantly different from the behaviour at nearby reference sites. The attraction was inversely related to distance to the wind farm and was primarily recorded during periods of adverse wind conditions. The attraction behaviour suggests that migrating raptor species are far more at risk of colliding with wind turbines at sea than hitherto assessed.
authors.affiliation: DHI, Agern Alle 5, 2960 Hørsholm, Denmark hsk@dhigroup.com.
authors.forename: Henrik
authors.identifier: 0000-0001-8835-3166
authors.initials: H
authors.lastname: Skov
authors.affiliation: BirdLife Denmark, Vesterbrogade 138-140, 1620 Copenhagen V, Denmark.
authors.forename: Mark
authors.initials: M
authors.lastname: Desholm
authors.affiliation: DHI, Agern Alle 5, 2960 Hørsholm, Denmark.
authors.forename: Stefan
authors.initials: S
authors.lastname: Heinänen
authors.affiliation: Department of Bioscience, Aarhus University, Grenåvej 12, 8410 Rønde, Denmark.
authors.forename: Johnny A
authors.initials: JA
authors.lastname: Kahlert
authors.affiliation: Vattenfall, Jupitervej 6, 6000 Kolding, Denmark.
authors.forename: Bjarke
authors.initials: B
authors.lastname: Laubek
authors.affiliation: DHI, Agern Alle 5, 2960 Hørsholm, Denmark.
authors.forename: Niels Einar
authors.initials: NE
authors.lastname: Jensen
authors.affiliation: DHI, Agern Alle 5, 2960 Hørsholm, Denmark.
authors.forename: Ramūnas
authors.initials: R
authors.lastname: Žydelis
authors.affiliation: DHI, Agern Alle 5, 2960 Hørsholm, Denmark.
authors.forename: Bo Præstegaard
authors.initials: BP
authors.lastname: Jensen
mesh_terms: D025041:Animal Migration; D000818:Animals; D003718:Denmark; D005060:Europe; D005426:Flight, Animal; D009792:Oceans and Seas; D011210:Power Plants; D020304:Raptors / Q000502:physiology*; D058998:Remote Sensing Technology; D014919:Wind
keywords: avoidance; collision; marine wind farms; migration; raptors