Wednesday, April 28, 2010

The immature bald eagle, such as seen here, is sometimes mistaken for a golden eagle. However, young bald eagles have more white mottled into their coloration overall. The golden eagle is more solid in color, and it has a beak that is more blue-black, with a nearly black tip.

Eagles molt in patches, taking almost half a year to replace feathers, starting with the head and working downward. Not all feathers are replaced in a given molt. Until the bald eagle is mature, the replacement feathers are of different colors. As adults, the belly and back are dark, while the head is pure white. The distinct juvenile pattern, signaling that a bird is not ready to breed, may reduce aggression from territorial adults.

As juvenile bald eagles mature, their head and tail feathers gradually turn white; simultaneously the eyes and beak gradually turn yellow. Complete transformation to maturity is achieved sometime in the fifth year.

After fledging, young eagles stay near the nest for six to nine weeks practicing their ability to fly and hunt. The parents cannot tell juveniles how to hunt, they have to learn by watching the parents and practicing. During this time, they seem to spend more time looking at prey than they do actually attacking it.
Until the first winter after they fledge, young eagles near the nest are often still fed by their parents, but have little other contact with them. Although a young eagle has the instincts to hunt, it lacks the skills. Eventually, they learn to soar and spot prey. If food is scarce during the winter, it could die.

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