Bald eagles' heads turn white as part of their transition to adult plumage, which occurs gradually over several years. Key points in this transition are:
- At about 3 to 3.5 years old, bald eagles (called sub-adults) begin developing white feathers on their head and tail, but these areas are still mixed with brown flecking. Some dark patches near the eyes and on the tail usually remain.
- By about 4 to 4.5 years, the head is mostly white with some dark feathers, and the tail starts to become white with less banding.
- Around 5 to 5.5 years, bald eagles typically acquire the pure white head and tail adult plumage. Some may take up to 6 years or a bit longer to completely lose any dark flecking and get the fully white head.
- Once the adult plumage is acquired, it is kept for life.
Thus, bald eagles' heads turn white primarily between ages 4 and 5.5 years, with full adult white head feathers usually present by about 5.5 years old. This white-feathered head distinguishes adult bald eagles from juveniles and sub-adults who have darker and mixed coloration on their heads and tails.
