and there is this whole thing about birds having a wings.
i am the owner of an indoor cat and i am all for keeping cats indoors because of how many dead cats i see on the roads in my relatively densely populated urban area. if i won the lottery or something and i would be moving into a house with a garden, i would be scared to let the cat out because of the danger to her, not the birds.
it may very well be, but what most people don't realize is that the natural life of wild animals is not a disney fairy tale. their life expectancy is a lot shorter than that of the household pets and their death is often nothing to envy.