Preening refers to a bird grooming its feathers with its beak. Every feather has tiny interlocking hooks called barbs, and preening makes all of the tiny barbs line up like a zipper. Preening makes a bird look and feel its best. While preening, birds will also pluck dead feathers and pick the sheaths off of new growing feathers. You may also see your parakeet getting oil from a gland near the base of its tail and rubbing it into his feathers. This oil helps condition feathers and make them water resistant. When a bird preens another bird, it is called allopreening.