Here's what the BBC says about it:
"A
study published in 2009 looking at the US and Europe estimated that wind farms were responsible for about 0.3 bird deaths for every 1GWh of electricity generated, compared with 5.2 deaths per 1GWh caused by fossil-fuelled power stations.
It said this would equate to the deaths, every year, in the US, of about 7,000 birds caused by wind turbines, 300,000 by nuclear plants and 14.5 million by power plants using fossil fuels.
It's a fairly old study so this may have increased with the growth of wind power in the US or decreased with better understanding of how to mitigate the risks.
Another
study in 2012 came to a similar conclusion, finding that fossil-fuel powered plants killed birds during mining, through onsite collision, electrocution with plant equipment and poisoning.
Whatever the exact number, and how it compares with fatalities at fossil fuel plants, it's generally considered that any harm to birds could be mitigated by locating wind farms away from major migration routes and feeding, breeding and roosting spots.
The UK-based Royal Society for the Protection of Birds (RSPB) says that if this is done, wind farms will have "minimal impacts".
It says that there is a far greater long-term threat to birds and other wildlife - climate change. And it recognises the role of renewable energy in tackling this.
According to the LSE's Research Institute on Climate Change and the Environment, "the benefits for wildlife of mitigating climate change are considered by conservation charities... to outweigh the risks, provided that the right planning safeguards are put in place, including careful site selection".
It also points out that the number of birds killed by wind turbines pales in comparison to those killed by cats or traffic - although wind turbines are more likely than cats or traffic to affect rarer, more endangered birds."
https://www.bbc.com/news/science-environment-48936941
