Do cockatiels tail feathers grow back in?

It takes about 4-6 weeks for a feather to completely grow back. However, the amount of time depends on the overall health of the bird. It also depends if the feather has been broken off or if it has completely come out. A broken feather never grows back but needs to be shed by the bird during a moult before it regrows. When the flight feathers are clipped it will depend on how long before its next moult as to the time the feathers take to regrow. If the bird has just moulted and is clipped then it will be a few months as opposed to a bird that is clipped just prior to moulting.