An In-Depth Look At Bird Feathers

Learn about bird feathers, molting, pin feathers, feather destructive behavior and more.

Good feather health is vital to your pet bird's well-being. kheinz/Pixabay

When your wardrobe starts looking a little threadbare, it’s time to replace it, right? Your pet bird does the same thing. Except, instead of walking into a store and placing down cash, your pet bird uses a wonderful mechanism to make sure its garments are always impeccable: it molts its feathers.

Our pet birds’ feathers are multi-functional, so they need to be kept in tip-top shape. Feathers keep a bird warm, and they enable it to fly to get food as well as flee from danger. Feathers also help a bird attract a mate, and they help keep chicks warm, too.  A bird’s system is geared toward keeping these multi-tasking, multi-purpose feathers in good working order.


Birds do daily grooming maintenance (“preening”) using their beak. They run the microscopic parts of their feathers through the edges of their beak, essentially re-zipping the hooks that exist on each feather strand so that the feather creates a solid surface. While doing so, they also clean off the dry, built-up debris on the feather.

Most parrot species have an uropygial gland, or “preen gland,” although Amazon parrots and hyacinth macaws do not. The uropygial gland is the only oil gland on a bird’s body, and it is found at the top of the base of the tail. Parrots spread tiny, metered amounts of this oil on their beak and then run their beak throughout the feathers, spreading the oil.

Maintenance also requires cleaning. Periodically, sometimes multiple times each day, a bird utilizes whatever nature offers it to clean its feathers. Outside, birds utilize rain, puddles or other bodies of water, dew or rain droplets on leaves, or sand to help extra oils and dirt fall off the feathers. At home, we can provide our pet birds a fine-mist spray or take them into the shower with us. Some pet birds prefer wide bowls of water or moist leaves to rub up against. All of these methods of bathing give our pet birds the ability to help keep their feathers clean.


Even the best-maintained feathers have microscopic structures that eventually wear out and the feathers will no longer hold together properly. A bird periodically (usually up to several times each year) goes through a replacement cycle, where each feather is replaced by a new one. This is called a “molt.”

The molt cycle is a vulnerable time for a bird. During this period, the bird lacks its normal amount of feathers, so the functions they perform are not optimal. In addition, the growth of new feathers requires many nutrients, including calories, amino acids, vitamins and minerals. If there are any issues of nutrition or illness during this time, the bird’s body does not have the resources to grow normal feathers. As a result the feathers grow abnormally, or the bird delays molting altogether. Because resources out in the wild often follow seasonal patterns, molt cycles generally follow times when food is more readily available to provide nutrients for the growing feathers, such as in spring.

Different Molt Patterns

Different species of birds have different molting patterns. For example, ducks and geese typically lose all their flight feathers on their wings all at once, in spring and in fall. For a short period of time, these birds lose their ability to fly, and they stay on or around water during these vulnerable times. However, they regain the feathers all at once, quickly, to obtain very good function.

Birds detect clues of seasonal cycling, such as day length change, nutrient deficiencies (or abundance) and moisture in order to properly synchronize with the best time to grow feathers. Inside our homes, pet birds do not receive all the clues their ancestors in the wild receive. Because of this, not all pet birds in our homes molt in a consistent pattern.

That being said, most of our companion parrots, over several short bursts or fewer longer bursts of time, replace each larger feather at least once, perhaps twice a year. The smaller down feathers (a bird’s “underwear” if you will) are replaced at even more frequent intervals. During this time, feathers are released from their follicles either spontaneously or during preening. Sometimes it might seem like the bird has pulled out the feather but, in this instance, the feather needed little to no tension for it to come out. By watching carefully you can see this almost effortless loss of the feather. Feathers are generally replaced in a scattered pattern, so only a few feathers come out in an area at a time, leaving minimum of protection and flight ability. Most feathers are replaced symmetrically so, in a very short time, the matching feathers on the bird’s right and left sides are lost at the same time.

Pin Feathers

After the feather is lost, the body grows a new one, just as in the case of hair. However, growing a feather is a more complicated process because it requires active, growing cells up into the emerging feather. There is a circulating blood vessel bringing nutrients up into the developing shaft of the feather. The feather tissue is very delicate at this time, so the feather is encased in a protective, cylindrical sheath that is made up of keratin (which also is in fingernails). This makes the feather appear like a pin. This pin feather can come in several tones, including one that is dark at the base, which indicates the presence of the blood supply. Therefore it is referred to as a “blood feather.”

Eventually, the blood supply starts to decrease and absorb when the tissue has fully developed. While it is doing so, the protective sheath starts to peel off in tiny pieces during the preening process. Some people think these tiny pieces look like dandruff. During this time a bird might appear to be more itchy than normal. The feather is curled up inside the sheath and unfurls as it comes off, leaving a fully functioning feather once it is all cleaned off by the bird’s preening with its beak.

The bird can reach these pin feathers with its beak to preen feathers from the “shoulders” down but typically requires other birds in its flock to clean the feathers on its head and the upper part of the back of its neck. A person can fill this role by using his or her fingertip to gently pinch and roll the white part of the sheath that is at the tip of the feather. Otherwise, the remnant of the growing feather remains until the sheath eventually falls off. Nutritional deficiencies sometimes affect how easy or difficult sheaths are removed from the pin feathers, so if you don’t know if what you’re feeling is normal, contact your veterinarian.

The new feather, still with the blood supply although protected with the sheath, is still vulnerable to injury. The sheath might be weakened due to underlying health issues, such as infectious disease or nutritional deficiencies. Enough trauma can also cause the sheath to split or break, which causes bleeding, especially on a large feather, such as those found on the wings and tails. Historically, the standard therapy was to pull a broken blood feather no matter what. Doing so, however, increases the chance of injury to the follicle that produces the feather. Recently, more veterinarians recommend not pulling these blood feathers out unless the hemorrhage is likely to affect the bird’s health. (If you are unsure as to whether a blood feather should be removed, ask your avian veterinarian.)

Stress Bars

As mentioned before, producing a feather requires much in the way of resources (energy, nutrients) from the bird’s system. If any of these requirements are disrupted, or if the sheath is injured while the feather is being formed, there will be a weakness because the growing tissue was interrupted in growing properly. This creates a transverse line perpendicular to the long axis of the feather and is called a “stress bar” or “stress line.” The stress line indicates that the growth tissue was stressed with the reduction of nutrients supplying it. A large number of these bars can be indicative of some type of health issue within the bird and should be assessed as soon as possible by your bird’s veterinarian.

The molting process can be alarming because in some species, such as budgerigars, there are many feathers seen in a short period of time. Unless there is an indication of destruction of feathers and indication of bald spots, this is normal.

Wing feathers that had been previously trimmed are replaced throughout the molt cycle, allowing the bird to regain the ability to fly. This can be gradual, or in the case of species that are particular adept at flight, such as cockatiels, this re-growth can be all at once.

Wing Feather Trims

There are many thoughts on the concept of whether a bird should have its wing feathers trimmed (and therefore being unable to fly, but able to glide to the ground). There is no clear-cut answer, and it  depends on many factors, including the bird’s home environment and its interaction with family members including adults, children and other pets. Factors such as the likelihood of doors and windows being opened and shut, and the presence of ceiling fans, toxic plants and other potential dangers in the home helps determine whether there are more benefits than drawbacks to flying.

When a young bird “fledges” (i.e., learns to fly), it is a time of neural development that is not returned to in later development stages. This is the time when all the feathers have finished their initial growth, and the bird now has the ability to fly. Allowing the bird to learn to fly sets the stage for proper body and brain development. Wing feathers should not be trimmed until the bird is proficient at “flight navigation” (flying and safely landing on the cage top, perch or playgym). After the young bird masters the art of flight, you can then gradually trim more and more feathers so the bird is more and more limited in its flight range, until the bird is no longer able to maintain sustainable flight, and starts to drift downward and glides to the floor when it launches. This is the goal of any wing feather trim, even in a more mature bird: the ability to safely glide to the ground instead of crashing down hard because of a severe wing-feather trim. Only sufficient feathers should be trimmed to cause a gentle, short downward pattern. Too much taken off, and the bird could fall and hurt itself.

Injuries caused by excessive wing feather trimming can be immediately obvious. They can include fractured beak tips; splitting of the skin overlying the keel; rupturing of the skin under the tail; broken blood feathers of the wing or tail as they hit something on the way down; or injuries to the wings or legs themselves (including bone fractures).

However, injuries do not necessarily have to be visible to be present. There can be bruising and injuries to the body that are not necessarily noticeable by you, but they definitely affect the bird. The impact of the bird’s now flightless body falling can be similar to the slamming effects of a low-speed car crash. It can leave bones and muscles sore for days. This can cause behavior abnormalities and can even affect behavior if the bird starts to associate people with the pain it is feeling.

As in all health matters, prevention is the best approach, and your bird’s nature should determine the appropriate wing feather pattern.

For example, species that have to flap harder to fly (such as African greys and Amazons), and younger birds that do not have full flight muscle development, need less removed from their wing feathers than birds that are stronger flyers. These birds, such as cockatiels, macaws and some cockatoos, often need more flight surface removed.

Custom Wing Feather Trims

The further to the outside the feathers, the more lift and thrust. The feathers closest to the body are more used in turning, stopping and fine-tuning the flight pattern. Therefore, the best feathers to remove to keep the bird from flying high and long are the outer feathers. Removing the inner feathers and allowing several to be long on the outside, is the equivalent to keeping all the acceleration but disabling the brakes and steering wheel.

This wing feather trim might be more aesthetic in appearance, but it can compromise your bird’s health.

The trim point along the axis of the feather can also vary. For example, some birds (more likely African greys and cockatoos in my experience) where the wing is folded along (its flank), react adversely to sharp trimmed points that might touch there. Therefore feathers should be trimmed far out past the point where the feathers touch the flank (a common trim I use in African greys), or very close to the wing so that the trimmed points are covered by the coverts (the shorter feathers that overly the base of the feather). I use this pattern more commonly in cockatoos. In this way, the African greys have less flight surface removed and will more gracefully glide down, and the cockatoos will have more flight surface removed. And in other birds, I typically trim right under the edge of the coverts, which creates a scalloped edge. This reduces the chance of injury to new feathers growing in, because the base of the feathers that remain support the delicate growing feather.

Feathers: It’s All About Symmetry

If the bird’s wing feathers are trimmed symmetrically, there is an even, controlled descent. If there is asymmetry then there will be careening and cartwheeling; therefore, both sides should be trimmed to the same degree. Within species, there are individual differences in regard to strength and flight ability that will change the wing feather pattern prescription. You might need to make a note during each wing feather trim as to how it was done in order to see how the bird is flying versus falling afterward. Refer back to the notes in order to plan the next wing feather trim.

How long a wing feather trim will last before your bird is flying again depends on several factors. For example, if your bird is young, it might quickly develop the flight muscles as it matures and can do more flying with the pattern that worked to keep it from flying even a few weeks before. If your bird is about to enter a molt, it will replace the wing feathers that were just trimmed and regain the ability to fly as soon as the new feathers grow sufficiently to give the flight surface. If the trim was performed after a major molt finished, it might be months up to a year before the bird can fly sufficiently enough to warrant a re-trim.

Safe Restraint

Most parrots initially will not allow their wing feathers to be trimmed unless they are restrained. With positive reinforcement techniques, most can be taught to allow their wings to be touched and their feathers trimmed. However, if the wing feathers need to be trimmed and the bird has not yet associated the wing-feather trim with something positive, it will need to be gently restrained. Since restraint, if performed incorrectly, has risks for both the handler and the bird, only a person familiar with doing so should even attempt a wing feather trim with restraint. Watch an experienced bird groomer work with your bird until you feel comfortable doing so. Growing feathers should be trimmed beyond the blood supply (where there is mature feather) and therefore each feather should be examined carefully.

After a wing feather trim, keep the bird low and close to the ground until you find out how much lift and glide the bird has, to allow time for the bird to adapt to the level of flight that exists after the clip. This will help prevent injuries and pain.

Feathers are amazing structures that are very important to a bird’s life. It is our job as caretakers of these wonderful creatures to help our birds keep their feathers in tip-top shape. This includes providing bathing opportunities, optimized nutrition and health, and appropriate trimming (or not) of the wing feathers. In doing so, we provide the stewardship our wonderful companions require.

Feather Destruction

Feather destruction (sometimes described as picking or plucking), where the bird forcefully and/or prematurely pulls out the feather or chews at it so that the base stays in the skin but the feather is partially destroyed, is different in appearance to molting. There is bare skin (whereas with molting there are generally few feathers lost in any one place, so that no skin is bared.) With feather destruction, there might even be blood at the tips of the removed feathers. If your bird is picking at or pulling out its feathers, contact your avian veterinarian as soon as possible, because there might be an underlying medical cause.

Article Categories:
Birds · Health and Care

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