Yes they do but it takes a few seasons to acclimatize and notice that they do grow more down.And I have another question that might be silly. I know that many animals grow a heavier coat in preparation for winter. Do birds grow more feathers or thicker feathers as cold weather approaches? Is there a difference between tropical birds and birds that don't migrate for the winter as far as feather growth?
All parrots like temps of between 75 and 90 degrees. More importantly is when we start to use artificial heat that we also keep the humidity up (50% or higher is optimal).
Furnaces dry out the air a lot.