It's hard not to worry when your parakeet is sulking in the corner and the bottom of his cage is filled with feathers. He could just be molting, but it could also be the sign of another problem.
What Is Normal?
Parakeets molt for the first time when they're between 3 and 4 months old, and then about once a year after that. Unlike a lot of other types of birds, your parakeet won't wait for a certain time of year to molt, so it's not unusual if it happens at an odd time of year, like the middle of winter. Your parakeet should molt evenly, losing about the same amount of feathers on each side and shouldn't have any bald spots. It is normal for him to act a little crabby or sick during molting because it takes so much energy, but he should continue to eat, drink and preen himself.
It is not normal for your parakeet to molt more than once a year or to be constantly losing feathers. If this is happening, he is probably not truly molting. Artificial lighting can sometimes confuse your bird's body into molting when it shouldn't. The more likely culprit though is a virus. There are several viruses that can cause abnormal molting in parakeets. Have your parakeet checked by a veterinarian who can test for viruses if he is molting more than once a year.
Bald patches are not part of molting. A bird who is losing a lot of feathers, leaving behind bald spots needs to be checked for the cause. Illness, parasites, boredom, malnutrition and dry conditions can all lead to bald spots. He is probably pulling out his own feathers. It's best to have your parakeet examined by a vet if he has any bald spots. He may just meed more exercise, better food or more water for baths, but he could also be ill.
While it's normal for pin feathers, which can look odd, to appear during molting, the final feathers should appear normal. Pin feathers often look like dark black dots and can make the other feathers appear ruffled. If the full feathers look strange though, such as unusual lines, ragged edges or twisted shapes, there is something going on besides molting. Stress and poor nutrition can cause unusual feathers, so can disease. If you notice unusual feathers that are not pin feathers, contact your veterinarian.