Through the vibrant Karoo sunset a pair of Crowned Eagles glides along the crest of a table top ridge. One stalls and hovers for the briefest moments before both dive into the valley below.
Amanda and I are busy conducting a walk transect as part of our winter iteration of an avifaunal survey on a proposed wind farm near Cookhouse in the Eastern Cape, South Africa. While we speculate whether the pair of eagles were returning to their overnight roost spot or conducting a co-operative hunt for juvenile baboons climbing the krans, we both voice our concern over the impending transformation of the South African landscape as the second phase of wind farms is poised to bristle with numerous arrays of mega turbines.
Together as a husband and wife team we have conducted avifaunal surveys for the past 3 and half years in four provinces from the Sutherland plateau of Northern Cape, through the Garden Route, skirting the coastal plains of the eastern Cape and up to the escarpment of the Amatola mountain range.
In July of 2014, the farm known as the Jefferies Bay Wind Farm was officially connected to the Eskom power utility grid, the first of many large wind farms in the country. We had worked on the farm in the proposal stage and located a Martial Eagle nest tucked away in a hidden kloof. The nest was massive, hinting at an antiquity of more than a decade, and was constructed in the crown of a giant Outeniqua Yellowwood.
An avian species which is sensitive to habitat disturbance, we now hoped that our data would allow the environmental consultants to propose a plausible mitigation protocol that would secure the survival of these magnificent eagles and the other priority species on the site.
Proposed wind farms in South Africa have been located in the prime wind zones of the country, namely the Eastern Cape near Humansdorp and further north near Cookhouse and in the Northern Cape between Maitjesfontein and Sutherland. These three zones all have strong steady wind and have the added bonus of being close to large electrical sub stations which make it easy to feed into the national power grid.
While the avifaunal survey protocols have been compiled to emulate methodologies employed in Europe and North America, the uniqueness of the bird species in the prime areas for South African wind farms may require that mitigation protocols be adapted and new ones developed to ensure that sensitive priority species are not displaced or even killed once development is compete.
Unlike Europe where priority species are mostly flocks of migratory species that run the gauntlet of many nations across two hemispheres, local South African priority species are predominantly resident territorial species. Of special concern to us are the raptors. Their anatomy is one of the primary concerns that make them susceptible to the threat of wind turbines. As hunters, while on the wing, their skull structure has evolved so that their eyes face down allowing them to effectively search for prey below. This potentially predisposes them to not seeing any obstacle forward of their flight path, especially an obstacle that is a moving turbine blade. In addition, their height of gliding while searching for prey places them in the ‘strike zone’ of the turbine blades. Both these factors are a potential threat as they may be too focused while looking down to see the blades turning.
‘But surely they will see the blades and avoid them?’ We are often asked in social groups. One would hope that that is the case, but two factors need to be considered from the bird’s perspective.
Firstly, most of the hunting species in the region glide on air currents created by the landscape resulting in narrow zones of ridge and slope soaring. Unfortunately, this same wind on the edge of ridges is best suited for the turbines which create a conflict of interest between an area of food resource and energy resource.
Secondly, at optimum revolutions, the tips of the turbines move at between 200 and 300Km/h depending on design, a speed that may prove difficult for a bird to avoid while it is intently focused on hunting down prey. Indeed, vultures in Kenya have been simply sliced in half when they miscalculate their flight path through an array of turbines.
Packing up at sunset for the day we gaze at the hypnotic rotations of 66 turbines spouting from the skyline east of Cookhouse and reflect on the pristine landscapes we have walked through in the Roggeveld with the delicately balanced natural population of raptors. Or of the landscape determined flights of Cape Vultures near Elliot with no less than four colonies within a 40km radius into which a brace of wind farms has been proposed for the very epicentre of their flight paths. Should these projects proceed, we can only hope that safe flight paths are left undeveloped to secure their safety.
We can only hope as the country enters the second phase of wind farms in South Africa that developers have instigated bird strike mitigation procedures that remove all threats to the amazing and fragile bird life that we are blessed with.
In a few months we will learn how effective mitigation is as we begin post construction avifaunal surveys.