It's not just that small garden birds are very common, in general they've co-evolved with predators similar to cats and have adapted to deal with that (for exam

It's not just that small garden birds are very common, in general they've co-evolved with predators similar to cats and have adapted to deal with that (for example by nesting at height, having large broods, etc). There's some exceptions, mostly when cats get introduced to islands with few similar natural predators, but as a general rule it's probably not the most pressing problem. Large birds like eagles reproduce slowly and don't have the instincts to avoid wind turbines which in theory makes wind farms a serious threat to those species.