Overpreening is so common in parakeets that the practice is identified by the initials FDB -- "feather damaging behavior." When this behavior is concentrated around the neck, it can be a sign of extreme stress in parakeets. According to BirdChannel.com, more than half of pet parakeets exhibit some form of overpreening behavior.
Parakeets are sensitive animals who form strong emotional bonds with their owners and mates. They tend to react strongly to stressors such as loneliness and isolation. This can be especially acute when parakeets' hormones are raging as they go through adolescence. Purdue University scientists found that cage positioning factors heavily in a bird's stress levels. They found that birds whose cages allowed views of doors through which people entered and left were more likely to pluck their own feathers.
Parakeets, like all parrots, have delicate systems that require balanced nutrition. Parakeets should get a good mix of fresh fruits and vegetables, along with a quality dry mix. Artificial colors or fillers in some commercial food pellets can lead to malnutrition in parakeets. When a parakeet's nutrition suffers, he often will resort to plucking his feathers and chewing on them. Neck feathers are usually easy to reach, so he may start there.
Parakeets are intelligent critters who, like understimulated children, can become bored easily. If your parakeet does not have enough activities to keep her occupied, she may find entertainment by destroying things within reach, and that includes her own feathers. Do not let her spend too much time in her cage, particularly if it's a small cage. Make sure she has plenty of toys of her own. Parakeets love to play games, so make sure to play with her.
All parakeets are sun lovers. In the wild, they inhabit sun-soaked forest canopies. Consequently, birds kept in dark areas that lack abundant light can become depressed and start plucking their feathers. This is related to malnutrition, as parakeets get vitamin D from sunlight, and a lack of vitamin D in a parakeet diet has been directly linked to feather plucking. Often, feather plucking stops when birds are moved to more sunny or well-lighted areas.
Parakeets are prone to certain illnesses, including aspergillosis, a respiratory disease triggered when birds inhale certain strains of aspergillus mold. When a bird destroys his feathers in an irregular pattern on the throat or chest, he might be picking feathers that rest over the locations of infected air sacs. If you suspect a respiratory problem with your parakeet, take him to the veterinarian right away.