In one sentence, describe what the following article is about:

Birds are typically very clean creatures and they spend a lot of time cleaning, preening, and grooming their feathers. This is natural self-care behavior that is important for birds to do.  While preening, birds straighten out their feathers by pulling them through their beaks. This allows them to pull out dislodged feathers, clean out pests and debris, and spread preening oil across their feathers. Preening oil is produced from a gland near a bird's tail and the bird spreads it around to all of its feathers. This oil helps protect the feathers. If your bird has stopped preening, has ruffled feathers, and looks shabby, you should have it looked at by a veterinarian. This could indicate that it is not well. Bathing is an important part of feather maintenance for birds. If your bird stops bathing itself, that is a sign that it is no longer taking care of itself. This could signal depression, body pain, or lack of mobility. Your bird may simply take a quick bath in its water dish once in a while, so you may not catch it every time. However, you may notice water splashed all over the place in your bird's cage. This is a good indicator that your bird has taken a bath. Wing flapping can signal a lot of things, but one reason that birds do it is simply for the exercise. Birds in captivity still want to keep their wings in working condition, so flapping them around keeps the muscles conditioned to some degree. Your bird may also do this to get your attention or simply because it is happy.

Summary:
Look for preening behavior. Make sure your bird is bathing. Look for vigorous wing flapping.