Bald eagles (Haliaeetus leucocephalus) are not born with their distinctive white heads and tails. Instead, they undergo a series of plumage changes as they mature, which can take up to five years. While bald eagles are not actually bald, their name derives from an older meaning of the word, “white-headed”.

Plumage Changes in Bald Eagles

In their first year, bald eagles have a dark brown plumage, with white flecking on the underside of their wings, axillaries, and belly. Their beak and cere (the fleshy area at the base of the beak) are blackish. By the end of their first 1.5 years, the beak begins to turn yellow, but this process can be variable, with some birds retaining their dark beaks well into their second year.

During their second and third years, bald eagles undergo more significant plumage changes. In their second year, the belly becomes mostly whitish, while the head and breast remain dark, giving the bird a hooded look. In their third year, the head begins to whiten, and the belly darkens, often becoming predominantly white with brown flecks. The face, crown, nape, and throat also whiten, sometimes creating a faux osprey face. The beak and eye color also change during this period, transitioning from dark to yellow.

Acquiring the Adult Plumage

Image source: Pexels by Frank Cone

By the time bald eagles reach their fourth year, they have acquired their adult plumage, which is characterized by a white head and tail, and a dark brown body. However, not all bald eagles acquire this plumage at the same age. While approximately 25% of bald eagles acquire the adult plumage at 4.5 years, all or 100% of them acquire the pure white head and tail adult plumage by 5.5 years. Some birds may take up to eight years to acquire a pure white head and neck, but most do it in 5.5 years.

Differences Between Male and Female Bald Eagles

It is worth noting that bald eagles are not actually bald; the name derives from an older meaning of the word, “white-headed”. The adult bald eagle is mainly brown with a white head and tail, and both male and female adults have the same plumage, with the only difference being the size. Female bald eagles are 25% larger than males.

Conclusion

In conclusion, while bald eagles are not born with their distinctive white heads and tails, they undergo a series of plumage changes as they mature, which can take up to five years. By observing the plumage, beak, and eye color, it is possible to estimate the age of a bald eagle with a reasonable degree of accuracy. Bald eagles are not actually bald, and both male and female adults have the same plumage, with the only difference being the size.

References:
– Reddit post on bald eagles’ plumage changes
– How to identify bald eagles
– Wikipedia article on bald eagles
– Aging and identifying juvenile and sub-adult bald eagles