My take on the whole 'where are all the zombies' is that for part of it i'm sure some have starved and died off, but i think the main reason is that Ink has gathered them into his army. I'm also betting that they have been on the move, but where will they show up?? The colony, ft Irwin, Boulder?? If they go to Boulder they have some desert and the mountains to cross...plus i think they would have been spotted by the flights between ft Irwin. Ft Irwin, idk, maybe, but ive noticed that there does always seem to be zombies around the colony.