In your climate you certainly don't NEED to insulate for typical chickens , but you wouldn't regret it either. If you're kind of 'on the fence' about it, you might consider leaving the walls open inside and just waiting til some cheap or free materials come your way and doing the job then.
If you only insulate one thing, make it the ceiling or walls, not the floor -- the bedding you put on the floor is *already* serving as a decent amount of insulation and it's cheap to use more, and relatively little heat loss or condensation problem happens at floor level anyhow. Walls and ceiling are much more important to insulate.
If your ceiling is exposed metal or plastic on the inside then you will definitely ought to insulate it, to avoid intractable condensation/frost/humidity problems in wintertime. Even if it is plywood, if your ventilation for wintertime is a bit iffy, your air quality may benefit from insulating there.
Good luck, have fun,
Pat
Good luck, have fun,
Pat