About twice a year cockatiels molt. This is the same thing as shedding. They also pick at their feathers if they are stressed. You can buy molting conditioner at the store. It helps with stress and also the amount of feathers your bird molts. I just buy it at Walmart. It's like $1.25. It is in a can and looks like their food. I just mix his food with the molting conditioner. They love it!