Sounds like “stress bars” or “stress lines.” These black bars occur as feathers are developing and a bird gets either emotionally or physically stressed. Physical stress could be a health problem he or she was suffering at a time, such as an infection for example; or a significant deficiency of important nutrients (i.e. malnutrition). Emotional stress would be caused by such events such as moving into a new home or when major changes are occurring in their environment (new family member or another pet. Birds are also very sensitive and will pick up on stress that family members may feel (divorce, loss of a loved one, etc.). So this is the time to evaluate their diet and overall state of health; and – if stress is a likely cause – to keep stress at a minimum. Once the root of the problem has been rectified, the feathers will usually grow in normal during subsequent molts. Sibylle