Monitoring reports provided by specialists from each site allowed the organisation access to information regarding bird passage rates, abundance, and fatality rates. The specialists, explained Ralston, did transect walk, transect drive, focal point surveys and vantage point surveys in collecting a comprehensive set of data before each wind farm was operational, and did the same after but included fatality searches as well, looking for carcasses beneath the wind turbines.
Constraints in the Birdlife SA review were that it did not have access to the raw data, making comparative analysis challenging, and the survey methods were only partly standardised, she noted. The study period was also only limited to one year of operational phase monitoring, with a couple of interim monitoring reports thereafter.
Statistical analysis of the data showed that in South Africa, on average, four birds per turbine per year are killed - less than the number killed by cats, yes, but, as Ralston pointed out, species matter.
"We looked at which are the species that are being affected - which are the species being found beneath the turbines - and we found about 36% of those found beneath the turbines were raptors, which is concerning because raptors are apex predators and play really important roles in our ecosystems and many of them are threatened," explained Ralston.
According to Ralston, all the wind farms in the study reported at least one fatality of a bird species threatened with extinction.
The top 20 species assessed as likely to be vulnerable to the impacts of wind energy compared to the observed impacts
"The numbers at this stage are relatively low and, certainly compared to other threats, wind energy is a miniscule threat, but something like a Black Harrier - we've had two [kills] during the study period and subsequently three more - there are less than 1000 breeding pairs left. If we are to have wind energy built within their habitat without any controls, it's potentially a major threat within the future."
Operational phase mitigation
While the study remains ongoing, Birdlife SA is using the results obtained so far in strategic environmental assessments and site screenings to ensure wind farms are sited appropriately. In terms of wind farms that are already operational, Birdlife SA aims to engage with stakeholders to promote operational phase mitigation, and to look into technology-based solutions.
"These are issues that are beyond borders - they're not issues that SA faces alone, and to address the issues, we also need to go beyond our silos, we need to work with engineers, we need to work with wind farm developers.
"We also need to remember the big picture - wind energy might threaten some of our species, but so does climate change. In fact, between 24-50% of our bird species are threatened by climate change. There are moves afoot internationally and the Convention of the Conservation of Migratory Species has established a task force to try and facilitate global cooperation to address some of these challenges, so the truth is this is an issue that's getting global recognition," said Ralston.