In the Field

Bald Eagle Stages of Development – Bald Eagle Facts

Bald Eagle Stages of Development – Bald Eagle Facts

Did you know that our National Bird, the bald eagle, doesn’t get its trademark white head and tail until they’re five years old? The bald eagle goes through several stages of development in their first few years of life which is reflected in their plumage (feathers).  Juvenile and immature bald eagles look quite a bit different from fully mature, adult bald eagles. In fact, it’s very common for people to mistake these birds for the Golden Eagle.

golden eagle vs juvenile bald eagle
Juvenile bald eagles (right) are often confused with Golden eagles (left).

A “juvenile” eagle is one who is still under 1 ½  years of age. A bald eagle starts out with a coat of down feathers which is replaced by dark brown feathers as they grow into fledglings and prepare to leave the nest. Fledging juveniles keep this dark brown plumage with a lightly colored belly for about six months before beginning to molt and develop into another plumage.

Over the next year or so, an immature eagle’s feathers become gradually lighter in color with more white spots or “flecking” as it’s called starting to emerge. At this time, many young eagle’s beaks also start to change color as well.

juvenile bald eagle
A juvenile bald eagle swooping in to catch a meal.

At around 2 ½ years immature bald eagles can show a wide variety of color variations, with some remaining mostly dark brown with white flecking mixed into a lesser degree, and others having light brown feathers with more dominant white flecking. It’s also at this time that a bald eagle’s eyes will start to change color and will begin to lighten up.

Bobby the Bald Eagle - Children's Wildlife Book Series- by Joseph Classen

When a bald eagle is between 3 ½ to 5 years old they become what’s known as “sub-adults.” At this stage of development the white flecking and spotted feathers begin to fade out and the eagle starts getting more of a solid-colored plumage on its wings and body, while the tail and head start to slowly transform into the trademark white coloration. It’s also at this stage of development that the beak turns more yellow and the eyes continue to lighten.

sub adult bald eagle
A sub-adult bald eagle, soon to develop its trademark white head and tail.

When a bald eagle reaches 4 ½  to 5 ½ years, they become fully mature and have at last attained their signature black (actually dark brown) and white plumage, yellow beak and light yellowish eyes. Some adult eagles may still have a little bit of brown flecking in their head still, but it usually fades out completely after the fifth year. So there you have it, that’s an overview of the stages of development and plumage variations of the bald eagle. Check out the video below to see more…

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Resources (In the field experience, Avian Report, and Alaska Dept of Fish and Game)