Is it necessary to cover a bird's cage with a blanket or towel at bedtime?
It depends on the situation. In my experience, I've met birds that prefer to remain uncovered during bedtime, as well as birds that simply couldn't sleep without their "security blankets".
On average, birds need about 12 hours of good, quality sleep each night to remain in peak condition. Much like people, their rest periods can be disturbed by noise and bright light. For this reason, many owners choose to cover their birds at night.
If noise and light are not a problem, try leaving your bird uncovered for a few nights to gauge his reactions. If the bird appears to like being uncovered at night, then it is fine to leave it that way. If, however, the bird appears sluggish or begins to exhibit bad behavior, the best thing to do is keep him covered at night to ensure that he gets a good night's rest.
As long as a dark, quiet, and somewhat secluded area is provided for a bird to sleep in, most will thrive without being covered at night. Remember, however, that sleep is vital to a bird's well-being. If you are in doubt about your pet's reaction to being uncovered, play it safe and resume covering the cage at night.