Killing the Mouse

I once laid my whole newborn rat litter side by side (all 15 of them) And each one had it's head resting on it's neighbors back. Very cute. Wish I got a pic.

Thank you both very much for your input. I was definitely trying to figure out the most humane way to kill off these little guys, since I'm not trying to get rid of them to be mean or because I dislike them but because they are food. I'm not really worried about wild animals coming into the carport after them, as Buddha is generally patrolling along the fence there from the late afternoon until it's time to come in for the night and very little gets past him -- as an opossum found out last week. At what approximate point do they outgrow the hypoxia resistance? Our pink rats are destined to become ball python snacks, but I want to wait until they're hoppers or so before putting them down.