Hello; There is indeed in a natural setting a balance established between predators and prey. I guess an argument can be made that a human neighborhood is not a natural setting for what it is worth. I do think there are at least estimates as to the damage caused by pet cats but I do not have those numbers at hand. I guess my gripe is more about the well fed pet being allowed to roam and kill. I get such is in the nature of cats but will draw a distinction about including these pets into the mix of an areas "normal" predator prey relationships. As you say it is not the cat's fault but more the cat's owner at fault.without having real numbers to hand of the local populations of the animals that cats routinely bring home, then no one can really say, with any degree of accuracy, if they are killing these animals and placing them in real danger or whether the cats are actually just keeping the numbers in check which is what nature intended, to a degree.
I ride a bicycle for exercise along a busy highway. I see road kill quite often. Skunks, deer, possom, racoon, dogs, cats and even birds. I guess the birds have not evolved yet to fly a bit higher over a road. I suppose if our vehicles are around long enough those that fly too low will be selected against and those who fly higher will be selected for.
My impression for some time has been that house cats are an overall negative for local wildlife. Again I cannot provide evidence for such . My believing it is true does not make it so.
Hello; Yes the human set the stage but the cat did the deed.but in reality it was the lighthouse keeper who caused the ground nesting birds demise, by introducing what can only be described as an invasive species to the island mix.