You wanna talk about COLD hardy? Last night when I went out to shut my coop door for the night it was 1 degree F. This morning when I went out to open the door and feed it was -9 F. I apparently didn't see one of my 15 week old white plymouth rock hens curled up in the snow last night. She came happily clucking over to me this morning after staying out side all night in -5 F - -10 F. That is what I call a tough bird. I never heat my coop and we have had several cold snaps into the negative teens. This is my first incidence of accidentally not getting all my birds in for the night in these temps. Amazing how tough they are.