Eagles and other birds will lose flight feathers symmetrically during molting season. However, if an eagle loses a feather on one wing through injury or accident, it will not automatically shed the same feather on the opposite wing to maintain balance.
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One such notion claimed that when an eagle loses a feather on one wing, it will automatically shed the same feather on the opposite wing to maintain balance. A quick Google search revealed that the idea was popularized on a Reddit post in 2016, and various iterations have since made their rounds on the internet.
Snopes spoke with an avian care specialist at the Alaska Raptor Center who said that it is true that eagles and other birds will lose flight feathers symmetrically during molting season. However, when an eagle loses a feather on one wing through injury or accident, it will not automatically shed the same feather on the opposite wing to maintain balance.
Molting is a natural process that occurs when a bird sheds old feathers to make room for new growth. Bald eagles, both juvenile and adults, will molt every year, shedding their specially evolved aerodynamic feathers to make way for new ones. The National Eagle Center, a Minnesota-based environmental conservation organization, wrote that bald eagles will molt the same primary flight feathers on each wing simultaneously to maintain balanced flight — and it can take up to three months to fully replace a molted feather.
But if a feather is pulled out or damaged on one wing through an accident or injury, it is unlikely that the same feather on the other side will automatically be shed. Eagle feathers are made of keratin and grow from the skin in much the same way as our fingernails, and each feather grows out of skin follicles like human hair, according to the American Eagle Foundation. Damage to the follicle takes time to repair and regrowing a healthy feather in its place can take even longer.
So, while it is true that a bald eagle will symmetrically lose flight feathers during a molt, it is inaccurate to suggest the bird will “automatically shed” a feather to maintain flight balance. That claim is simply one for the birds.
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Alaska Raptor Center – Rehabilitation. Education. Research. https://alaskaraptor.org/. Accessed 11 Mar. 2022.
Bald Eagle Biology | American Eagle Foundation. https://www.eagles.org/what-we-do/educate/learn-about-eagles/bald-eagle-biology/. Accessed 11 Mar. 2022.
Bald Eagle Fact Sheet | U.S. Fish & Wildlife Service. https://www.fws.gov/media/bald-eagle-fact-sheet-0. Accessed 11 Mar. 2022.
tbbgreen. “TIL When a Bald Eagle Loses a Feather on One Wing, It Will Lose a Feather on the Other in Order to Keep Its Balance.” R/Todayilearned, 25 Feb. 2016, www.reddit.com/r/todayilearned/comments/47ibr1/til_when_a_bald_eagle_loses_a_feather_on_one_wing/.
“When a Bald Eagle Lose a Feather on One Side, Does It Lose the Same One on the Other Side?” Quora, https://www.quora.com/When-a-bald-eagle-lose-a-feather-on-one-side-does-it-lose-the-same-one-on-the-other-side. Accessed 11 Mar. 2022.