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Juvenile
Eagle Behavior |
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Why
might the migration of a juvenile eagle be different from the migration
of an adult eagle?
Each spring, we're so busy tracking eagles as they migrate back to their nests,
that we often forget about the many birds who are too young to nest. After
all, it takes Bald Eagles somewhere between three and a half and five years
to grow in the white head and tail feathers that mark them as adults; some
of them don't actually start breeding until they are seven years old.
So what are all these immature birds doing when the adults are hard at work
raising new eagles?
On Vacation
Young eagles spend much of their time traveling. Scientists can't accurately
predict where a given nestling will wander. They can disperse in any direction,
and learn their own patterns for when and where to migrate. They do seem to
remember where they've been, and in the first couple of years many of them
find the places where they will spend most of their winters, and the place
where they'll build their permanent nest.
Playing House
In the same way that children build pretend houses with blocks, some young
Bald Eagles build pretend nests. Scientists in Saskatchewan watched some eagles
in immature plumage as they constructed stick nests. These nests were apparently
just practice ones, because they were never actually used for laying eggs or
raising babies.
Practice Makes Perfect
Bald Eagles are not good at catching fish when they first leave the nest. They
pick up dead fish along shorelines first, and then progress to picking up dead
fish floating in rivers and lakes. It may take months for an eagle to start
catching its own live fish, and much longer for it to become reliable at fishing.
So young birds must spend more time fishing to catch the same number of fish
as adults.
All in all, the first years of a Bald Eagle's life are a time of enormous learning
and exploring the world around them.
Journaling Question
- A baby robin leaves the nest when it’s only 13 days old, a hummingbird at 21 days, and an eagle at 70-84 days. Why do you suppose young eagles take so long to grow up compared to hummingbirds and robins?
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Before reading further, think of as many reasons as you can. Then see our answer in "Eagles are Big Babies."
National Science Education Standards
- The behavior of individual organisms is influenced by internal cues (such as hunger) and by external cues (such as a change in the environment).
- Many characteristics of an organism are inherited from the parents, but others result from an individual's interactions with the environment.
- Behavior is one kind of response an organism can make to an internal or environmental stimulus.
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