When they are tired, they switch positions with another bird. We have a cardinal that has lost every feather on its head. There can be two reasons that you have a cardinal that is bald. Your cardinal could be a young birds with feathers still developing. Another reason could be that your cardinal has feather mites that eat the feathers and cause the bird to go bald.
Birds are unable to preen themselves on the head which allows for mites to exist there.
Your cardinal soon will molt-in a new set of feathers and no longer will be bald. Amy Until 1834, the Black-capped chickadee was not realized as a separate species from the Carolina Chickadee. The Carolina chickadee prefer foothills and valley. The Black-capped chickadee are found at higher elevations. To tell the difference between these two birds look at the wings.