This month, the American Wind Wildlife Institute (AWWI) released its latest analysis of bird fatalities with the focus on small passerines (commonly referred to as songbirds). (masterresource.org)
They also researched cats (and several other human - related causes of bird mortality) and while it's challenging to arrive at accurate figures, they estimate cats, both pet and feral, cause somewhere between 100 and 350 million bird fatalities per year. (catsandbirds.ca)
Bird fatalities caused by wind turbines are DWARFED by a factor of 1000 when compared to those caused by stationary structures (skyscrapers!). (instituteforenergyresearch.org)