How small can chickens squish?

[hrmalexandra]

Hi, I've seen a lot of advice on how predators can squish up and get IN a run or coop, but I'm curious how small a chicken can squish up to get OUT. One of mine may have pulled a disappearing act today and I want to know how to chicken-proof a day run in the future!

 

[Leah-yes I know I'm crazy]

I have a sebright that is half mouse. She can squish through a 1" vent hole. I have no idea how she gets out. I have my neighbor convinced she isn't even a chicken...just some wild bird that hangs around for the cheap corn.
I use tent stakes every 12" along the bottoms of temporary runs because no matter how level you think your yard is when it comes to keeping wire tight it is not. Added to that, for chicken wire to work it has to be secured on all edges because it does have a lot of stretch to it, especially diagonally (like the bias of fabric).

 

[hrmalexandra]

Really wish I knew all this last night ....