One should stay away from evil, as the wise have taught us. Danish scientists have recently discovered in a research on a wind farm that most birds know that they must avoid flying into the rotation diameter of wind turbine blades, and that 99.9% of pink-footed geese and cranes in the nearby area of the wind farm have exhibited an “avoidance response”.

After two years of observation at Klim Fjordeholme, scientists have mapped out the flight paths of birds through radar detection and laser binoculars, and discovered that the local pink-footed geese and cranes may perhaps coexist peacefully with the wind turbines in the area as 30,000 pink-footed goose and cranes avoided wind turbine blades during flight.

Bearing similarities to the outstanding nature reserve and wild bird sanctuary Vejlerne, the Klim Fjordeholme wind farm has an installed capacity of 67.2MW, and 22 units of 3.2MW onshore wind turbines that measure at 93m in height for each hub, where the rotation diameter and the tip of the wind turbine blades are measured at 113m and 149.5m respectively. The wind farm was completed in 2015.

According to the Environmental Impact Assessment (EIA) of Klim Fjordeholme, bird strikes between birds and wind turbines within the area of the wind farm cannot exceed 75% of mortality rate for pink-footed geese and cranes, which prompted scientists to observe the impact of wind turbines on nearby birds.

Subsequent to the completion of the wind farm in 2015, the research team began conducting two tests that lasted 1 and 3 years respectively during the period of August to May of the following year, in which they had patrolled 11 wind turbines every 3 days for any feather, traces, and casualties surrounding the wind turbines, as well as mapped out the flight paths of birds by using laser binoculars, binoculars, and radars. The research team believes that this study might be of help to systematic rangefinding and the measurement of flight altitude, and may assist in establishing 3D trajectories for each individual bird later on.

Jesper Kyed, Head of Environment and Sustainability for Vattenfall, a multinational power company that operates the wind farm, commented that the experiment has indicated that birds do indeed fly around or above the wind turbines, and the research team believes that the results are relatively positive, since there are almost no bird casualties due to collisions, and that the installation of wind turbines does not conflict with the natural environment.

However, this is merely the result of a single wind farm, and the close observation on the impact of wind farms on wild animals and birds in the future should be placed on more than 1-2 species. According to the study of the US Fish and Wildlife Service, 140-500K birds die each year in the US due to wind farms, which also impact large and endangered birds that require conservation, including golden eagles, vultures, burrow owls, red-tailed hawks, Swainson’s Hawks, and peregrine falcons. Large birds and birds of prey have a lower reproduction rate than small birds, thus the mortality rate is of essence. In addition, wind turbines also derive effects for bats, as the wind pressure produced by the blades of wind turbines will create damages to bats’ internal organs, which is one of the reasons behind the death of 888K bats year.  

 (Cover photo source: Klim Vindmøllepark Monitering af fuglekollisioner)