(in North America) and if we hadn't hunted and driven away the bobcats lynx and ocelots that would have killed those bird for food (along with the weasels stoat

(in North America) and if we hadn't hunted and driven away the bobcats lynx and ocelots that would have killed those bird for food (along with the weasels stoats ferrets ermine mink foxes and other predators) how many birds would they have killed?