Eagles, like all other birds, molt. They molt four times before reaching adulthood.
Eagles go through a molting experience with their feathers, which occurs symmetrically.
Eagles undergo a symmetrical molting process with their feathers. If a primary feather molts on the left-wing, the same feather molts on the right wing concurrently. This can help maintain flying equilibrium.
The molting process is still a mystery. However, before sexual maturity, which occurs at the age of 5, young eagles go through four distinct plumages before reaching sexual maturity and attaining their adult plumage, which is the fifth plumage type.
The duration of a molt can be influenced by a range of biological and welfare factors (such as food availability, the density of other eagles, and others), and not all molts are complete.
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What is molting, and what are the uses?
Molting is the process of feather shedding and renewal. During the molt, the bird’s reproductive function is completely shut down, and the body supplies of nutrients are replenished.
The production of new feathers or coats (a trait shared by most animals) is a natural process designed by nature to preserve the birds’ ability to flee from predators and provide additional protection against harsh weather conditions.
Adult birds undergo molting once a year under natural conditions, although some individuals might experience it twice in one year and just once every two years in others.
Feathers are phenomenal, intricate, and gorgeous structures. They, like hair or fur on mammals, serve a variety of critical functions.
Feathers act as an insulator, regulating body temperature and shielding birds from the environment (cold, heat, and water).
They are a huge part of aerodynamics and flight. They are employed for concealment, courtship display, territorial protests, and to signify sexual dimorphism in a variety of species.
Molting serves two purposes: it replaces old or injured feathers, and it creates distinct plumage that can be used to determine a bird’s sex, age, and season, as many birds have distinct hot and cold weather `plumages.
In addition, since most birds molt once or twice a year, each molt is either a partial molt or a complete molt.
For partial molt, only a portion of the feathers are replaced during that cycle, and the remainder will be replaced the next year.
A complete molt occurs when every feather is replaced throughout a single cycle.
Related: Here is an article I wrote on why eagles fly so high
At what age do eagles molt?
Eagles start undergoing the molting process and color changes from the first year of their life.
The silky down feathers the birds hatch with are replaced gradually with stronger feathers good for a flight when they can fly for the first time at about 12 weeks of age.
They eventually molt and replace all their feathers each year after that. During their juvenile years, between 1 and 3 years of age, their feathers are predominantly brown.
By 4-5 years, when they reach sexual maturity, white feathers replace the brown head and tail feathers.
Eagles go through five significant molts or plumage changes. It begins at 11-14 weeks (that is ½ year), which is the Juvenal Plumage.
Then the basic plumage occurs at 1½ years (Basic I), 2½ years (Basic II), and 3½ Year (Basic III), which is primarily from the head plumage and iris, beak, and core color.
Lastly, the definitive happens in the 4½ year (Basic IV) and all 5½ years (Basic V).
Eagles only change their plumage once a year, and both sexes have similar feathering. Juvenal plumage is the initial layer of real contour feathers formed in the nest, followed by basic plumages in succeeding years.
Molts, which begin in spring and last in late fall, is used to acquire basic plumages preserved until the following winter.
What happens when eagles molt?
Eagles replace their flight feathers in small batches to avoid starving while waiting for replacements.
Additionally, they molt symmetrically, shedding identical feathers on either side to keep their flying balanced.
Molting is a gradual process, and it may take several weeks to restore all feathers.
Due to this gradual symmetrical molt, only a tiny flight limitation remains during the six-month molting period.
How often do eagles lose their feathers?
Eagles shed their flying feathers almost every year once they get their full “adult” plumage.
However, because they have flight feathers and rely on them to forage for food, they do not lose them all at once.
Instead, eagles symmetrically lose feathers, one on the right and one on the left. In this manner, they are not rendered helpless and unable to maintain body temperature or fly in quest of food.
It is a progressive, ongoing process. Eagles normally replace their primary flight feathers once a year.
After that, they will symmetrically shed their flight feathers (the same feather on each wing).
After then, it may take up to three months to completely replace a molted flight feather.
They continuously molt their contour feathers (outer body feathers) and downy feathers (insulator feathers) and will normally replace all of their feathers over two years.
Also check out this article I wrote on eagles flying at night
What time of the year do eagles molt
Adult birds molt in stages during the spring, summer, and fall, whereas flying feathers molt only during July, August, and September.
Do eagles lay eggs while molting
Eagles do not lay eggs while molting. At approximately 4 to 5 years of age, an eagle reaches sexual maturity and is ready to reproduce.
Bald eagles, for example, have a completely white head and tail, which indicates sexual maturity.
Golden eagles also develop adult plumage between the ages of 4-5 years, when they reach sexual maturity and typically begin reproducing.
How can you tell if an eagle is molting?
It’s tough to detect when an eagle is molting due to the gradual nature of the process.
Additionally, they molt symmetrically, making it impossible to determine which feather on their bodies is missing. Also, eagles have little affinity for humans.
Just like every other bird in this world, eagles do molt. They go through 5 important primary processes till they achieve adult plumage.
After that, they molt every year to replace their worn-out feathers. Eagles’ mooting is a natural process, although they can also go through forced molting.