Bald Eagle

Bald Eagle

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Bald Eagle Migration Update: February 12, 2003

Today's Report Includes:


New Eagle Now Online! Peter Nye’s Journal
Eagle V31
with Peter Nye and Kathy Michell
Photo: Gene Weinstein
Meet Eagle V31, who was captured last Wednesday and now sports a new satellite back-pack. Catching eagles isn’t easy! Peter Nye’s day began at 1:58 am. He had to put the rocket net and bait in place before dawn. His goal was to catch an adult eagle that will migrate north to Canada this spring to nest. But by 8 am, he had attracted at least 12 eagles; some were immature birds (not old enough to nest), and others were adult eagles whose leg-bands identified them as U.S.-nesting eagles. Add to that the challenge of blasting a rocket net around the right bird without harming the others! At last Nye and his assistant, Kathy Michell, managed to capture Eagle V31, an adult male. But will this eagle migrate to Canada in the spring? "I'm as anxious to find out as you are!" says Nye.

Reading Peter Nye’s journal is second best to spending the day in the field with him. There’s so much to learn!

Challenge Question #3:
"If you knew nothing about bald eagles, how many new facts about eagles could you find in Peter Nye’s story? Include your list of facts with your answer."

(To respond to this question, please follow the instructions below.)

Photos of the capture process from a previous year.
Eagles at deer carcass
Rocket net
Deployed! Was an eagle captured?

First Winter Range Map and Satellite Data

What do you suppose "winter range" means? In our February 19th update we'll discuss the term. Meanwhile, think about that while you plot the latest satellite data from each eagle on your map (or print and analyze our map).

Link to Latest Data:


Why Count Manatees, Monarchs and Eagles in January?
Discussion of Challenge Question #1

Last week we posed Challenge Question #1: "Explain why you think January is the best time to count manatees, monarchs and bald eagles. (Clue: The annual surveys take place in January for all of these species for the same reason.)"

"I think January is the best time to count manatees, monarchs, and bald eagles because they're all in one place and not really moving around much before migration," replied Megan of St. Wendelin High School.

Exactly! The reason, in a single word, is COLD. Cold causes manatees, monarchs and bald eagles to congregate (group together). This makes counting them much easier for biologists! It's interesting to compare and contrast the reasons each species congregates:

  • Manatees are very sensitive to cold. Biologists try to schedule their surveys for the coldest days, when the manatees gather at their favorite warm water spots (such as Blue Springs State Park).
  • Monarch butterflies from across eastern North America gather in one tiny region of Mexico for the winter. They form their tightest aggregations in January. Biologists count the butterflies when they’re packed together tightly, and too cold to fly.
  • Bald eagles congregate in areas where food is available, especially around open water where they can find fish and waterfowl. ("Open water" refers to those portions of lakes, rivers, and streams that are not covered with ice.) Peter Nye trapped Eagle V31 in such an area, which is why a dozen other eagles came to the bait.

The Importance of Conserving Winter Habitat
During the summer in the northern hemisphere, mild conditions are found across huge portions of North America. But in the winter, the cold climate forces many animals to migrate to warmer places in the south. There, they must share limited habitat with many individuals. This is why protecting winter habitat is especially important. Acre for acre, its loss can have an impact on many more individuals.
Why Migrate? Discussion of Challenge Question #2
Challenge Question #2 asked one of the most baffling questions about migration: "If eagles migrate south for the winter, why do they bother to go back north? Why don't they just stay in the south?"

Congratulations to Mike, Chris, Lisette and Kriten of Iselen Middle School in New Jersey for trying this very difficult question. They knew the answer must be related to food, and understood that food would be available in the north.

"Eagles only migrate when they need food… When they go back to the North, there will be more food for them. The cycle then repeats itself."

Peter Nye thinks about it this way:

If the eagles all decided to stay where they wintered, things would get pretty crowded in a hurry! So even though there is food available in New York in the summer--and some eagles do stay--others migrate north. The eagles that migrate north will take advantage of a rich, though temporary, food resource. Only during summer months is food abundant in the far north, and readily available to bald eagles. When fall and winter come, they must migrate south to survive.

How do the eagles know to go north in the spring? Peter Nye explains:

"Bald eagles have an inborn tradition to their general area of fledging, called 'fidelity,' which draws them back there. This instinct has probably evolved over thousands of years. The rationale behind nest-site fidelity is that since eagles were successfully born in a certain area, the chances of their success at nesting in the same general area are probably pretty high."


Teacher Tip: Building Students’ Vocabulary With Journey North
Reading Writing Selection
New!
Reading and Writing Connections

Vocabulary is essential to comprehension. Students need to apply strategies before, during, and after reading to understand texts. Journey North provides a wealth of informational texts to help students learn about words in meaningful contexts. Use the following ideas to help students build and extend vocabulary skills during your Journey North studies.
Instructional Strategy Spotlight: "Lead Preview"
Prior to reading a selection, share just the first paragraph with the class. From the title and this "Lead Preview," students write questions and predictions to set a purpose for reading.
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 #3
3. In the body of EACH message, answer ONE of the questions above.

The Next Bald Eagle Migration Update Will Be Posted on February 19, 2003

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