heating options for outside aviary?

We recently transitioned our green-cheeked amazon to an outdoor aviary (his open cage is sitting inside the aviary). He seems very content and we do not see any signs of stress. The aviary has a good roof, solid back and partially solid sides. It is on a cement pad. As I reviewed previous posts about preparing for winter, it is obvious that "cold" is a relative term. We are in the San Diego area so typical nights are 40 - 50 degrees, though it can get down to freezing.

Many of the posts address heating options for a bird housed inside. My question is what, if anything, should we consider for the bird to keep him warm through fall/winter. Is he likely to get into a nest box or something similar? We have contemplated a three sided box with a perch, but not sure if it would help much or if he would even consider using it. Since he should be protected from rain by the structure of the aviary, perhaps we do not need anything and just allow him to adjust to the temperature. He is healthy and had a complete vet check with blood work just a few months ago.

We could also consider an Avitemp heat element/reflector which would have to be mounted outside the aviary (or inside a wire cage mounted inside the aviary in order to protect the bird from the hot surface); my concern with this option is that it is "always on" and may not be necessary in our relatively mild climate.

We'd appreciate your voice of experience. Thanks so much.

The main thing is all you have to provide is an area where he can be out of the weather if needed so building a partition that's covered on all 4 sides would be a good idea to do. As long as he is acclimated he should be fine but just keep an eye on him just in case.