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Specialist Studies


  • have collected some of the first data to show how large Eagles and Harriers use habitat around wind farms in the Western and Eastern Cape, and Lesotho;

  • were able to capture the first photographic evidence of a turbine strike of a Martial Eagle Polemaetus bellicosus at an operational wind farm in the Eastern Cape, see attached PDF (Photographic record of a Martial Eagle killed at a Jeffreys Bay wind farm); and

  • have used these data to draw up the first Eagle and Harrier Guidelines in relation to wind farms in South Africa.

Martial Eagle killed by turbine

White-tailed eagle deaths on the small island of Smøla have been reduced to zero over a 6-year period by the introduction of black blades. One blade per turbine, on 4 turbines, were painted black and compared with white blade turbines nearby
(Stokke et al, 2017, B. Iuell pers comm).

Their results showed that the black blades killed no more eagles, whilst the white blades continued to kill eagles at an average of 6 birds per year.

This innovative and clever mitigation we now hope to introduce to various wind farms in Africa to reduce the high rate of raptor deaths - see Making Green Energy Greener (below).

Video credits: Arild Magnus Soleim (Smøla wind farm Manager)

Eagle mortalities at an operational wind farm in
South Africa

As very few operational wind farms exist in South Africa there is little in the way of data for bird and bat mortalities in relation to them.


Black Harrier Guidelines for Impact Assessment, Monitoring and Mitigation (23 July 2020)

Dr RE Simmons, S Ralston-Paton, R Colyn,

Dr MS Garcia-Heras 

Birds & Bats Unlimited have been involved in the first drone experiments to test observer efficacy. 

     Satellite tracking of raptors and mitigating collision risks
  Specialist studies include:

  • the satellite-tracking of raptors and bats - to understand their foraging, breeding and migratory behaviour in relation to renewable energy farms;

  • using this data to assist Developers in placing turbines with sensitivity to vulnerable species.

A tagged raptor passes through a proposed wind farm in Lesotho. These data allow us to help Developers place turbines with sensitivity to vulnerable species.

Collision-prone bustards and raptors - power line surveys


Some collision-prone species require special survey techniques to understand where         they breed and how they are affected by power lines. We have undertaken:

  • several specialised studies of Bustards, Verreaux's Eagles and Black Harriers to determine how they are affected by power lines and proposed wind farms;

  • power line surveys to determine the mortality rate of bustards, Blue cranes and flamingoes deaths which are often under-represented in EIA studies;

  • to promote the use of diurnal and nocturnal line-markers
    and bird diverters;

  • to promote the use of staggered pylons to reduce bustard 
    collisions. We predict that by doing so bustard deaths
    could be reduced by almost 45%.

A Kori bustard found beneath power lines after a rain-storm in the Northern Cape.

From 22 operational wind farms in South Africa:

  • An average of ~4.1 fatalities occur per turbine per year; 

  • At one Eastern Cape wind farm  ~1 raptor per month is killed by turbines; 

  • 15% of these are Red Data species; 

  • Many of these fatalities could be avoided.

Green solutions to reduce fatalities include:

  •  Placing farms well away from hot-spots of activity;

  •  Placing (3-km) buffers around nests to keep turbines     well away;

  •  Surveying new areas using specialists to ensure no Red   Data species occur within the boundaries;

  •  Shut down turbines at critical (migration) times;

  •  Paint a blade black to increase visibility to eagles;

  •  For vultures: reduce animal carcasses on site, and attract birds away with vulture restaurants [new!];

  • For associated power lines, stagger the pylons to reduce bustard collisions [new!].

Stokke et al. 2017. Visual mitigation measures to reduce bird collisions –experimental tests at the Smøla wind-power plant, Norway.  Unpubl presentation of Norwegian Institute for Nature Research. Norway.

All bird fatalities on Smøla reduced by 71% (and eagle fatalities reduced by 100%) at turbines with a painted blade relative to unpainted turbines.

46,000 Bustards alone are killed on power lines each year. We promote the use of staggered pylons, line-markers and bird diverters.

Northern Cape, South Africa: Dr Rob Simmons illustrates the morphology of a Black Harrier Circus maurus chick in an interview with HomeBrew Productions for"The Secret Life of the Circler".

Staggered pylons. By using staggered pylons we predict that bustard deaths could be decreased by about 45%. This will be tested in Namibia in the coming years on a 400kV power line that will run over 350km.

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