I think where people have the disconnect is they don't realize that egg and poop actually use the same vent to exit the body, that there aren't separate openings like there are for humans.
This thread has taken an interesting turn while I've been gone.
At a flea market today I saw a man selling different varieties of geese. I saw a pair of geese that look like pilgrim, but they were much smaller than I would have expected. I asked them what breed they were and he stared at me...