Bald Eagle

Bald Eagle

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Bald Eagle Migration Update: February 19, 2002

Today's Report Includes:


Field Notes from Eagle Eye Nye

Hi Kids,
Here's the latest migration map and data from the eagles!
Link to Latest Data:

If you had my job, what would you say you've learned so far about eagle behavior?

  • Which eagle has moved the most?
  • Which has moved the least?
  • Do you think the eagles will begin to migrate soon?
  • Will they all take off at the same time?

Keep an Eye on Eagle E63
E63 on Capture Day
with Amy Rabuck and Kathy Michell

Have you noticed that one of the eagles isn't anywhere near New York? We captured Eagle E63 in southeastern New York last spring on March 1st. At the time he was at one of our state's largest overwintering areas. We tracked him north last spring and had a very interesting surprise this fall. He hardly even stopped in southern New York on his way south, and went all the way to the Chesapeake Bay! So it seems likely he was a Chesapeake winterer on his way back north when we caught him last spring. Time will tell what he does this spring. Do you think he'll leave earlier than the New York eagles, since he's further south where it's warmer? His pattern certainly seems unique; I haven't noted any of our wintering birds going down to the Chesapeake Bay area before.

Until next time,

Eagle Eye Nye
New York State Dept. Environmental Conservation
Delmar, NY
Discussion of Challenge Question #1
Lessons Learned from Over-wintering Eagles
In our last update we asked "Based on information from his study of over-wintering eagles, what important steps are being taken for eagle conservation in New York?"

Here are Peter Nye's comments: "The data provided by these Hudson River eagles has given us tremendous information about what are the most important habitats to them here in NY. Based on this study, we have prepared "critical habitat" maps of areas along the Hudson River, which we are already using to help manage the land for bald eagles to see to it that their most important habitats are not destroyed or over-used by people. That is exactly why we conduct such research and how we use it."

Did Vermont students see Nye's Eagle E49?

Ms. Thurber's students in Ferrisburgh, Vermont knew: "In New York, people are using the information about where eagles live to decide what to do with the land. The people are going to try and keep a place for eagles to live."

They also had a surprise when they looked at the migration map. One of Peter Nye's Eagles, Eagle E49, was right near their school in January. "We wonder if the eagles we have seen are the ones that have the backpack on!" they said.
You're the Scientist: Challenge Question #3
As we learned last week, Peter Nye looked closely at the eagles' behavior to find out what habitat they were using.

How hard is this to do? Divide your class into 7 groups so each group can chose their own eagle. Use the data we've provided so far and make a "winter range map" for your eagle. (Or copies of our map to analyze.) How far and how often do the eagles move? What body of water might each eagle be using for food? How are the eagles' ranges similar to one another, and how are they different? Your job is to define each bald eagle's home range or "winter range." (See definitions below.) Try to write the best verbal description you can. When your class has analyzed the behavior of each eagle, compare your results and then answer this question:

Challenge Question #3
"Based on one month's data, which eagle seems to have the smallest home range? What body of water do you think the eagle is using?"

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

Home on the Winter Range: Some Definitions
Here are some definitions that should help with your work today:

Home Range: The area an animal occupies in the course of its normal daily activities.

Winter Range: The area an animal occupies in the course of its normal daily activities during the winter months. (The winter range is simply a seasonal variation of the home range.)

Territory: The portion of the home range that an animal defends against intruders. (The intruders may be of the same or of a different species.)
Human Home Range: Challenge Question #4
To put these eagles' movements into perspective, compare them to your own travels. What is your home range? Describe the area that you occupy in the course of your normal daily activities. Is your winter range different from your summer range? If so, think of the reasons why.

Challenge Question #4
"How does an eagle's winter range compare to your own? How much of your home range do you consider to be your territory?"

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

Discussion of Challenge Question #2
Eating on the Road
Eagles eating deer carcass which Nye uses to attract eagles for satellite backpacks.

"How can eagles eat road-kill and other carrion without getting sick? What adaptations might eagles have that make such food safe for them?"

Garrett and Dustin, also from Ferrisburgh Central School in Ferrisburgh, Vermont, said they think, "The eagle must have a very good digestive system. The eagle might have saliva that would kill the germs. There are other animals that are scavengers, and they do not get sick from eating carrion. Scavengers might have more digestive juices than other animals. This would let them eat meat that was already dead."

Great thinking! Eagles swallow big chunks of fish and sometimes dead mammals or birds, bones and all. To digest them and to prevent sharp, jagged bone edges from piercing their intestines, eagle stomachs produce extremely strong acids. These acids also destroy most bacteria, so when eagles are scavenging on dead fish and other animals, they won't get sick. Interestingly, although eagles eat roadkill, they DON'T have an adaptation that another scavenger, the vulture, has--a naked head. Perhaps since eagles take most carrion in winter--when the dead animals are frozen and not likely to be covered with maggots--eagles don't need featherless heads the way vultures do.

Bald Eagle Adaptations from Head to Toe
This spring we're looking closely at eagles, from head to toe. Each week, we'll pose a Challenge Question related to the next week's featured adaptation. Remember: There's always a WHY behind WHAT you see. So whenever you see an unusual behavior or body part, ask yourself WHY...

Are you ready for this week's adaptation?

The Tail--Challenge Question #5
An eagle's tail is designed for flight, but also for its fishing and scavenging lifestyle.

Photos USFWS

Challenge Question #5
"Why do you think the eagle's tail:

    • Is sturdy and short?
    • But is also long enough to _____?
    • Can widen like a fan when the bird is in flight?
    • Turns white when the eagle is 4-6 years of age?"

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

Ask the Expert Opens February 22
Does your class have questions for the Expert? Beginning this Friday, your questions will be accepted for Bald Eagle Expert Peter Nye. Submit them any time in the next 2 weeks BEFORE the March 8, 2002 deadline at 5 p.m. (Eastern Time).


How to Respond to Today's Challenge Questions:

IMPORTANT: Answer only ONE question in each e-mail message.

1. Address an e-mail message to: jn-challenge-eagle@learner.org
2. In the Subject Line of your message write: Challenge Question # 3 (#4 or #5).
3. In the body of EACH message, answer ONE of the questions above.

The Next Bald Eagle Migration Update Will Be Posted on March 5, 2002

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