Birds that get eaten tend to have high reproductive rates, and if predator levels drop their population gets so high they start to die from hunger or disease (which spreads faster in crowded conditions). Many predators eat an incredible number of animals - a large owl may eat several small birds every day for itself, and a multiple of that if feeding nestlings. Cats aren’t unique here.
Domestic cats can be a threat to specific populations already endangered by other factors, but usually those are ground animals. Cats being a threat to population levels of birds in most of the world just isn’t believable to me.
Birds that get eaten tend to have high reproductive rates, and if predator levels drop their population gets so high they start to die from hunger or disease (which spreads faster in crowded conditions). Many predators eat an incredible number of animals - a large owl may eat several small birds every day for itself, and a multiple of that if feeding nestlings. Cats aren’t unique here.
Domestic cats can be a threat to specific populations already endangered by other factors, but usually those are ground animals. Cats being a threat to population levels of birds in most of the world just isn’t believable to me.