Overwintering button quail outdoors in the north?

[Denninmi]

Anybody keeping them outdoors in northern climates during the winter months? How much supplemental heat do you provide, what heat source?

Just wondering if it is necessary to heat an entire enclosure/pen, or can you just provide a heated space or two, such as a couple of heated shelter boxes, that they can move into as needed and sleep in?

I decided I don't like indoor button quail -- too much work keeping them all clean and fed. I put them outside last week and they are happier and so am I.

So, in the fall, I'm either going to do some kind of heated pens, or just give them away other than perhaps one or two pairs.