Where do birds (mostly garden birds) die?

Just wondered, you see so many garden birds e.g. sparrows, blackbirds, starling, wood pigeons, and you know they don't live for that long, but you never seem to find them dead in bushes or alley ways or behind fences etc etc (well, maybe the odd one every year or so dead on the floor, but not enough to cover how many must be dying on a regular basis)...