Birds naturally lose and replace their feathers regularly. Since feathers are naturally recurring, like human hair, they usually grow back after being pulled out. In some cases, however, underlying skin structures are so damaged by plucking that feathers won't return.
What the Pluck?
Plucking is when a bird intentionally pulls feathers out. Birds sometimes pluck their cagemates' feathers. When they do it to each other, it's usually a sign of aggression. When they do it to themselves, rooting out the cause can be more complicated. This behavior is usually chalked up to stress or boredom, but plucking can also result from skin irritation and infectious or metabolic disease. Parasite infestation is a prime culprit, as are yeast, bacterial infections and poor nutrition. It's important to seek veterinary attention from an experienced avian vet if your parrot has any unusual feather loss.
Could It Be Something Else?
Sometimes parrots lose feathers spontaneously due to disease. Hypothyroidism and psittacine circovirus are two possible causes. In addition, all birds naturally molt. This is when all of a bird's feathers fall out in a symmetrical pattern, then grow back in. Seeing your first molt can be shocking for a novice bird owner, but rest assured it's a natural, regularly occurring process and doesn't mean your temporarily un-feathered friend is sick. Wild birds and those housed outdoors naturally molt once or twice a year. Timing is more complex and less predictable in pet birds. Until you're familiar with molts, confirm them with your bird's vet.
Feathers grow from follicles in your bird's skin. Their movement is voluntary and controlled by muscles and ligaments attached to vanes underneath the skin. When a feather falls or is pulled out, a new feather grows from the same follicle. Newly emerging feathers are hair-like and covered in a hard sheath. They're called pin feathers because the sheath is rather pointy and resembles a pin. They're also called blood feathers because they contain blood vessels that supply oxygen and nutrients to the growing tissue. If your bird breaks a blood feather, it will bleed. Most birds remove broken blood feathers on their own, but if yours doesn't, you will have to intervene and pluck the remaining feather to prevent dangerous loss of blood. When the feathers mature, the blood vessels atrophy and die, and the bird rubs or pulls the sheath off, allowing the mature feather to emerge.
Your parrot's plucked feathers may not grow back if he's inflicted significant damage to the follicles by repeated plucking. The feathers are imbedded in living tissue, and pulling them out before they're ready to fall out can damage this tissue. This happens when portions of the follicle itself adhere to the plucked feather, or when tissue is damaged from bleeding and clotting inside the follicle.
Angela Libal began writing professionally in 2005. She has published several books, specializing in zoology and animal husbandry. Libal holds a degree in behavioral science: animal science from Moorpark College, a Bachelor of Arts from Sarah Lawrence College and is a graduate student in cryptozoology.