We all know that turbines and soaring birds don’t mix. So what is being done to help our avian nomads as they pass these whirring legions marching across the Estrecho Natural Park, one of the most important raptor migration bottlenecks in the world? We report on the Compensatory Measures Project, just one strand of the immensely important work carried out by our conservation partners, Fundación Migres.
As we round the corner of the coast road, in the hills high above Tarifa, most of our tour groups let out a gasp of awe at the stunning views of Morocco. This is often closely followed by a gasp of shock, as their gaze falls on the imposing ranks of wind turbines lining some of the coastal hillsides.
At just nine miles wide, here the Strait of Gibraltar is at its narrowest point between Europe and Africa, making it the chosen crossing point for over 300 million migratory birds, journeying between these continents twice a year.
A humungous sixty percent of Europe’s raptor population passes through here, as well as virtually its entire population of White Storks. Swifts also cross here in staggering numbers, with more than 400,000 passing through the area during peak times. This migratory spectacle is one of the most uplifting, life-affirming natural events we have ever seen, and simply has to be experienced to be believed.
With some 350 different species recorded, the list of birds in the area is extensive. At migration times there are Honey Buzzards, Western Ospreys, Red-rumped and Barn Swallows, Sand and House Martins, Pallid, Common and Alpine Swifts, Common and Great Spotted Cuckoos, races of Yellow Wagtail, Western Bonelli’s Warblers, Common and Iberian Chiffchaffs, Golden Orioles and Turtle Doves amongst many others.
At any time of year, birds in the area include Crag Martins, Blue Rock Thrushes, Crested and Thekla Larks, Lesser Kestrels, Tawny, Little and sometimes Eagle Owls. A wide range of nesting raptors, including Bonelli’s Eagles, Short-toed Eagles, Common Kestrels and Peregrine Falcons are common in the area. Around Tarifa there are colonies of Griffon and Egyptian vultures, the most southerly in the Iberian peninsula, with 70+ pairs of Griffon Vultures and six pairs of Egyptian Vultures breeding in 2017.
So how did these feathered millions end up running the gauntlet of the wind farms, adding to the perils they already face?
Back in 1993, when the area was still military land, the original two windfarms were commissioned, approved and built. The 20 MW Planta Eólica del Sur (PESUR) project and the 10 MW Energía Eólica del Estrecho (EEE) farm totalled 269 turbines. They were straight away mired in controversy, with local conservation groups and independent experts presenting evidence in 1994 of high avian death tolls(1). The corpses of 13 different species were allegedly found at the wind farms, either killed on impact or by electrocution on power cables, including an Eagle Owl, White Storks and Lesser Kestrels.
A random corpse count of Griffon Vultures stood at around 30, with some apparently decapitated by the blades. Counter-claims at the time by the wind company’s managing directors suggested that the yearly death count was never higher than twelve birds in total, and others presented figures as low as two birds.
In some cases it was alleged that no real impact study regarding the birds was ever carried out. It was even alleged that, while risk assessments were carried out based on presence of resident birds, the experts simply ‘forgot’ to account for the hundreds of thousands of migrating soaring birds that pass through twice a year!
Spain had (and still has) an ambitious plan for alternative energy generation, and the Tarifa area was to be its spearhead. Development of a proposed 2000+ turbines in the area were to provide a sizeable chunk of Spain’s 20% renewable energy target by 2020.
One can only imagine what it would have been like to be a fly on the wall in the many meetings that must have taken place, leading up to the declaration of the area as a Natural Park in 2003. With the area now protected, and acknowledged as an Important Bird Area by Birdlife International, extensive study and intensive mitigation work would be needed to reduce the negative effects of existing farms and prevent the creation of new ones in high-risk areas.
Enter Fundación Migres. This private non-profit organisation had been monitoring the area’s extraordinary migration event with daily counts during peak times since 1997.
In 2003, the companies whose memberships form the Tarifa Wind Power Association (AET) signed agreements with Fundación Migres to work on the Compensatory Measures Project for La Janda Windfarms, dramatically expanding their remit.
During the seventeen year project, their task was to find ways to reduce bird mortality in the windfarms, find out the effect of the farms on local raptor populations, and establish recovery programmes for more affected species, as well as raising awareness locally about environmental conservation and renewable energy.
The high-quality, independent science they have generated since their inception has added considerably to the world’s knowledge on wind farms and their effects on birds. It is helping develop better protocols for Environmental Impact Assessments (EIA) and mitigation measures to reduce turbine collisions.
Their work has generated both disturbing and promising results. A three-year study of 20 operational wind farms took place between 2005 and 2008, as the 323 turbines gradually came online(2). Over the study period, the research team found 596 dead birds – a devastating 1.33 birds per turbine per year, which is among the highest rates of wind farm mortality ever published. 36% of the dead were raptors and included 23 Common Kestrels, 13 Lesser Kestrels and 16 Short-toed Eagles.
By far the worst affected bird was the Griffon Vulture, with 138 found dead during the course of the study. Other studies suggest that most birds of prey can detect and actively avoid turbines without too much problem(3), but alas for the Griffon Vulture, for all its aerial prowess, agility is not one of its strong points. The bird relies on air currents and thermals to travel and has relatively weak flight, making evasive manoeuvres difficult.
All of these high-mortality wind farms had had EIAs carried out according to accepted methodology, had been accepted as low-risk areas, and had been licensed according to the law. The way raptors use the air currents and topography of an area is complex. It seemed site-scale EIAs based on bird abundance did not account for this, so could not adequately predict the threat level of proposed turbines.
However, interestingly, the study also found that the vast majority of these deaths could be attributed to a very small number of turbines. A new study was undertaken(4) – what if, by controlling function of these high-risk turbines, bird mortality could be reduced?
During 2006, body counts on 13 windfarms with 296 turbines had illustrated that most of the deaths were being caused by just ten turbines, distributed amongst six windfarms.
During 2008–2009, the team implemented a selective stopping program – when Vultures were observed near these deadliest turbines they were simply turned off till the threat had passed. Encouragingly, the Vulture mortality rate was reduced by 50% with only these ten turbines involved. The consequent reduction in total energy production for the wind farms was just 0.07% per year, a small price to pay.
This successful strategy was expanded to other high-risk turbines. When a high number of raptors are passing through, or individual birds are in danger – especially Griffon Vultures or the Critically Endangered Egyptian Vulture – the turbines are simply turned off.
With Migres-trained wind farm ‘watchmen’ on high alert, the whole shutdown process – from spotting a risk, to phoning it in, to stopping the relevant turbine – takes less than two minutes. The annual mortality – previously exceeding 200 vultures – has been reduced by 60% across the whole area(4). The accidents happen mostly during the autumn migration period when young birds – both resident and from all over Europe – are passing through the area. Though this is still a horrible price to pay for clean energy, this level of loss is at least thought to be sustainable from a population size point of view.
The process is far from perfect. A locally-breeding Egyptian Vulture was killed by a turbine last year, and two the year before. A drifting radio-tagged Lesser Spotted Eagle also hit a turbine, but seemingly recovered its wits and moved on, after sitting dazed in one spot for two days. We ourselves have been devastated to witness a majestic Honey Buzzard, hanging on an air current, lose control for just a brief second and get sucked backwards into the blades. And this is without even touching on the as yet unmitigated effects the turbines have on bats and other wildlife.
The end of the windfarm cooperation project in 2020 is fast approaching, putting the future of the turbine-stopping measures in doubt. With funding for Fundación Migres in decline, also at stake is one of the greatest sustained efforts for monitoring migratory birds in Europe, not to mention the invaluable research they generate.
It can be hard to believe that wind farm development was ever given the go-ahead in such a key area for the birds of the East Atlantic flyway. But it’s important not to forget the bigger picture. Many more birds are killed by traffic, power lines, radio and television towers, glass windows, and due to human activities such as poisoning and illegal shooting, not to mention habitat destruction.
Badly located as they are, the ever-spinning blades of the Straits supply around 20% of Andalusia’s power. Like all locally-damaging ‘renewable energy’ sources, they are there because of our insatiable appetite for consumption – of fossil fuels, of meat, of stuff we just don’t need. As the planet warms, ecosystems are disrupted and the Sahara creeps ever larger. For the millions of avian nomads that pass the turbines unharmed, the biggest peril is whether they still have breeding and wintering habitat to go to.
(1) Watts-Hosmer (1994) Bird deaths prompt rethink on windfarming in Spain. Windpower Monthly
(2) De Lucas et al (2012) Weak relationship between risk assessment studies and recorded mortality in wind farms. Journal of Applied Ecology
(3) De Lucas et al (2004) The effects of a wind farm on birds in a migration point: the Strait of Gibraltar. Biodiversity and Conservation
(4) De Lucas et al (2012) Griffon vulture mortality at wind farms in southern Spain: Distribution of fatalities and active mitigation measures. Biological Conservation