Door/entrance question

[oskizzle]

I have been building a quail pen similar to this, and am curious how big I need to make the door/entrance for quail to get through? I'm looking for a height/width. My goal is to maximize protection/warmth in the wood enclosed area as we get cold winters in the midwest, so I want something that is big enough for bob white and/or coturnix quail to get through, yet minimize the amount of wind that will blow in.

Thanks for the help!

 

[oskizzle]

I inadvertently put this in the wrong section, should be under quail - my apologies.