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Bald Eagle Migration Update: May 7, 2002
Today's Report Includes:
- Latest News and Migration Map
- Divided Duties: How Eagles Share Their Nesting Chores: Link to Lesson
- Challenge Question #21
- Eagles, Fish and the Food Chain: Discussion of Challenge Question #18
- Safer Diet for Loons than Eagles: Discussion of Challenge Question #19
- If You Were an Eagle: Discussion of Challenge Question #20
- Year-End Evaluation: Please Share Your Thoughts!
Latest News and Migration Map
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Highlights This Week:
- All of our Bald Eagles are now on territory. Even E63 has settled down in the same region that he occupied last summer.
- Golden Eagle A20, however, is still on the move. Our final migration update will be posted next week. We'll have to enlarge our map if he keeps heading north!
Divided Duties: How Eagles Share Their Nesting Chores
What's taking place on the nesting grounds? In order to have Bald Eagles in the future, Bald Eagles living today have to reproduce. This involves a LOT of critical steps, and scientists are still trying to figure out a lot of the details. Here is a list of some of the chores the parents must do in order to raise their babies:
- select territory
- defend territory against other eagles
- build or repair nest
- chase away predators
- lay eggs
- incubate eggs
- turn eggs
- cover eggs before leaving them alone
- catch lots of fish for nestlings
- feed young at nest
- sit on nest to brood young
- shade babies from hot sun
- feed and protect young if they fall from nest
- encourage young to fly
- teach young to fish (and/or supplement with food)
Whew! That's a lot of work! Fortunately, an eagle pair shares a lot of the responsibilities. To learn more about how and when they go about performing these chores over a nesting cycle, see our
Then see if you can assign a pair of eagles their chores with this
When you're done with the Chore Chart, think about the ways a pair of eagles divides their nesting chores. How is this different from the ways a pair of hummingbirds divides the same duties? Then answer
Challenge Question #21:
"Male and female eagles are almost identical in appearance, but male and female hummingbirds are very different. Is this related to the ways a pair of eagles or hummingbirds divide their nesting chores? Explain."
(To respond to this question, please follow the instructions below.)
Eagles, Fish and Food Chain: Discussion of Challenge Question #18
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Last time we asked, "Do you think a small, medium or large fish would potentially contain more toxins? Explain why."
A large fish has the most toxins per gram. This is for two reasons. First, the larger the fish, the larger a percentage of its body is fat. Fat is the part of the body that stores the most toxins. Also, the larger the fish, the older it is. This means that its body has been accumulating toxins over a longer lifetime.
We humans can read fish consumption guidelines to learn how much fish is safe to eat. Unfortunately, eagles are functionally illiterate, so they can't read this!
Safer Diet for Loons than Eagles: Discussion of Challenge Question #19
We asked, "Why do you think loons, who eat small and medium-sized fish, have had fewer problems with environmental contaminants than have eagles, who eat large fish?"
There are actually two reasons for this. First, as we said above, large fish have more toxins. But also, loons
virtually always eat live, healthy fish. Bald Eagles are scavengers, who eat dead fish. Some of these fish may
have died because they had such a heavy load of environmental contaminants. Also, eagles feed on dead and dying
ducks and loons, some of which may have died from lead poisoning or other toxins. And some of the dead deer that
eagles scavenge on during hunting season may have bullets or lead shot in their bodies that is eaten by the eagles.
If You Were an Eagle: Discussion of Challenge Question #20
We asked, ?If you ate 5-10% of your body weight, how many pounds of fish would you need to eat each day??
The answer to this depends on how much you weigh! For example, if you weigh 80 pounds, you'd need to eat 4 -
8 pounds of fish each day. If you weigh 100 pounds, you'd need to eat 5 - 10 pounds of fish each day. If you weigh
120 pounds, you'd need to eat 6 - 12 pounds of fish each day.
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Journey North |
How to Respond to Today's Challenge Question:
1. Address an e-mail message to: jn-challenge-eagle@learner.org
2. In the Subject Line of your message write: Challenge Question #21.
3. In the body of EACH message, give your answer to ONE of the questions above.
The Next Bald Eagle Migration Update Will Be Posted on May 14, 2002
Copyright 2002 Journey North. All Rights Reserved.
Please send all questions, comments, and suggestions to our feedback form
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