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Our Backyard Birds:
Why and When Birds Molt
I know what you’re thinking, “Dang, that is one ugly bird!”. No, it’s not a Frankenstein bird or a diseased zombie bird. It’s simply a cardinal going through a stage of life. Don’t be alarmed, it’s not contagious.
With a little research, I came up with some interesting facts about this strange behavior in birds. Here's what I learned.
Birds' feathers undergo noticeable changes during the year, with colorful feathers becoming temporarily dull after the breeding season is over. However, when the next breeding season arrives, the vibrant feathers return and the dull plumage is gone without a trace. This process is known as molting, and it is a natural part of a bird's life cycle that is painless and harmless. But why and when do birds molt, and how often does it happen?
Let's start with feathers. They have a strong and durable structure while remaining lightweight and flexible. Birds naturally replace their worn-out feathers by regrowing new ones, a process that often goes unnoticed. Each feather has a specific purpose, and they are used for various things such as flight and keeping birds warm. Flight feathers on the wings and tails are longer and stiffer, providing lift and steering. Body feathers, including down and contour feathers, help birds regulate their temperature.
Why do birds molt?
Birds need to replace their feathers when they become weak, worn, or damaged due to flying, injury, or abrasion. The process of shedding older, weaker, and damaged feathers and replacing them with new, stronger ones is called molting. This helps birds fly more efficiently and stay warm and dry in winter. Male birds of certain species molt before the breeding season to acquire a more vibrant set of feathers that helps them attract a mate. Strong feathers are crucial not only for flight but also for a bird's overall survival and reproduction. After their purpose is fulfilled, brightly colored feathers are shed and replaced with less conspicuous ones, allowing birds to blend into their surroundings and increase their chances of survival.
When do birds molt?
It is important to note that the timing of molting in birds varies depending on the species. Molting occurs during the development of a bird, from the fledgling stage to the juvenile stage, until it reaches adulthood. The process of developing adult plumage can take some time, especially for certain species which may undergo multiple molts before achieving their final adult plumage.
Swallows, hummingbirds, and thrushes are some of the bird species that undergo a complete molt once a year. During this process, they replace all of their feathers with a new and healthy set. Other birds, such as American goldfinches, buntings, and warblers, change their distinctive plumage during the breeding season, but later shift to a more drab appearance. These birds complete one full molt cycle and one partial molt every year. Although females of these species do not have such a stark difference in plumage, they still undergo a partial molt ahead of the next breeding season.
Certain bird species undergo two complete molts each year, particularly those that inhabit and breed in areas with dense vegetation. Due to the constant wear and tear on their feathers, they require more frequent refreshing compared to other species. Examples of such birds include wrens and bobolinks.
Molting is a natural process in birds where they shed their old feathers to make way for new ones to grow. It is not a painful process as the feathers being shed are already dead and fall off naturally. However, a bird may feel some slight discomfort while the new feathers are developing. These new "pin" feathers initially have a blood supply flowing to them while they are growing, which can make them sensitive to touch.
Bird molting is usually a gradual process for cardinals and blue jays, where feathers are replaced with new ones that look similar. However, there are some instances where the molt is more noticeable. Some birds experience a pattern of baldness during their molt, where they lose all the feathers on their heads at once. This is a normal occurrence and does not indicate any issues with the birds.
I hope you’ve enjoyed learning why and when birds molt. If this is your first time visiting my website or reading one of my blog posts, welcome, and thank you for joining us. Please subscribe here so you can receive updates on the next blog posts on Backyard Birding. You will also receive occasional discounts and newsletters. Remember to follow the Nature First and Leave No Trace principles and always strive to leave places better than you found them. Please share this blog post with your friends and family who have a love for birds, bird photography, or backyard birding.