Effects of wind turbines on flight behaviour of wintering common eiders: implications for habitat use and collision risk

Abstract

Summary 1.Wind energy is a fast-growing renewable energy source and many offshore wind parks will be erected in shallow waters (< 40 m deep) where various coastal bird species are found. The two main issues regarding offshore wind farms and birds are disturbance and collision risk. We studied the effect of wind turbines on the flight behaviour of wintering common eiders Somateria mollissima in order to identify the properties that cause disturbance and the factors that may increase their risk of collision. 2. The study was conducted at Tunø Knob offshore wind park in the Kattegat, Denmark. We attracted birds though the use of decoys located at increasing distances from the wind park. To discriminate between the potential disturbance effect of the standing towers from that of the revolving rotor blades, wind turbines were switched on or off alternately during 10 experimental trials. 3. Common eiders reacted strongly to the presence of wind turbines. The number of flying birds was significantly related to flight corridor location and position of the decoy group. That behavioural reaction was interpreted to be a consequence of their high speed and low-manoeuvrability flight occurring within the vertical height range of the wind turbines. The number of landing birds also reacted to the position of the decoy group in relation to proximity to the turbines, with the greatest effects observed within the wind park. Such avoidance behaviour might decrease use of otherwise suitable habitat. 4. The movement and noise of rotors affected neither the number of common eiders flying within corridors nor the number of birds reacting to decoys. This suggests that the avoidance behaviour observed was caused by the presence of the structures themselves and that eiders use vision when avoiding human-made structures. 5. Synthesis and applications . This study has demonstrated that common eiders avoid flying close to or into the Tunø Knob wind park. This behaviour may result in a reduction in habitat availability within and around wind parks, and raises concerns about the possible impact of the extensive development of large-scale wind parks in shallow offshore waters, which are the main feeding areas for sea ducks and other marine birds. Our results indicate that the disturbance effect of revolving rotor blades is negligible during daylight hours but highlights the need for studies to be carried out during hours of darkness and conditions of poor visibility (e.g. fog and snow). Until more insight is gained, we recommend caution when planning wind parks in areas of high sea duck densities.

Fitting statistical distributions to sea duck count data: Implications for survey design and abundance estimation

“…Data from a variety of sources suggest that Common eiders (Somateria mollissima), Long-tailed ducks (Clangula hyemalis), and Black, Surf, and Whitewinged scoters (Melanitta nigra, M. perspicillata, and M. fusca) may be declining [36,42], and proposed offshore energy development has the potential to significantly alter their wintering habitat [13,15,25]. Waterfowl managers need accurate and precise coast-wide winter abundance indices to assess trends and set annual harvest regulations, while energy regulators need predictions of spatial variation in abundance to inform responsible site placement of offshore structures and to guide future development activities.…”

Model-Based Estimation of Collision Risks of Predatory Birds with Wind Turbines

“…Biologists have highlighted the potential consequences for bird populations, such as disturbance and displacement (Percival 2000, Drewitt and Langston 2006, Larsen and Guillemette 2007, Pearce-Higgins et al 2009). Collisions result in high mortality rates, particularly for raptors observed in the vicinity of WTs (Erickson et al 2001, Hunt 2002, Barrios and Rodriguez 2004, Smallwood and Thelander 2007, Lekuona and Ursúa 2007, de Lucas et al 2008, Krijgsveld et al 2009).…”

Effects of Renewable Energy Production and Infrastructure on Wildlife

“…On the other hand, these installations create 'no-take zones' around them and their underwater vicinity that can function as artifi cial reefs, which leads to a greater abundance of many species (Wilhelmsson et al 2010 ). But if not properly planned and managed, these installations can adversely affect marine biodiversity through habitat loss, collisions with turbines, deviation of the migratory routes, noise and electromagnetic disturbance and navigational hazards for ships (Desholm and Kahlert 2005 ;Larsen and Guillemette 2007 ;Wilhelmsson et al 2010 ).…”