Bald Eagle

Bald Eagle

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Bald and Golden Eagle Migration Update: April 2, 2003

Today's Report Includes:

Latest Migration Map and Data
Use the data below to make your own migration map, or print and analyze our map:

Link to Latest Data:

Field Notes from Biologist Peter Nye
What a busy few days up there in the skies for our eagles! Makes you wonder, if there are hundreds of eagles--more likely thousands of eagles--flying way up there on certain days such as the last few, you'd think they'd need an air traffic controller! Here's the status of each eagle:
  • No doubt about this one--Bald Eagle E47 is clearly well on her way...
  • I was beginning to think Bald Eagle V31, the male bald we caught this winter, was one of our own New York nesting birds. Notice how "clustered" his fixes have been on the map? He was showing no signs of movement until he suddenly "hit the road" after March 26th in a big northeast move...No more worries about V31 nesting in New York!! Where do you suppose he’s headed?
  • Bald Eagle E49 started moving again around the 26th also. Were there good southerly breezes around that time?
  • Bald Eagle E50 is still hanging around, which is not surprising given his departure dates last two springs...
  • I’m still concerned that something is up with Bald Eagle E63, or his transmitter. I'd definitely expect movement north from his northern Chesapeake Bay location by now, and I haven't gotten a good signal since March 18th.
  • Golden Eagle A20 has started to move!
  • And Wow.Golden Eagle A00 is really trucking along now! Very interesting that it seems to be heading north east, toward Labrador, where our other golden eagles have gone. The 3 separate fixes for him on Sunday, March 30th are separated by less than 6 hours--but look at the progress! He did a lot of traveling on Sunday, maybe to beat the weather? A front came through here on Monday, with rain starting in the morning and wet snow in the afternoon. Maybe he was trying to get ahead of it on Sunday?

Here are the times of the 3 fixes, which the satellite gives in Greenwich Mean Time. Can you determine the local time? (For help, see example below.)

Fix #1: 13:38, Fix #2: 16:52, Fix #3: 19:07


Weather Forecast By a Bird? Challenge Question #14
Pete Nye says Golden Eagle A00 might have traveled on Sunday to try to get ahead of the coming storm.

Challenge Question #14
"Do you think it might be possible for an eagle to forecast the weather? If so, how?"

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

How Far and Fast Did He Fly?
Discussion of Challenge Question #11

"How far did Golden Eagle A00 move in the 1 hour and 37 minutes between his first two readings on March 19? On average, how many miles per hour did he travel?"

Brett went the distance for the first part of the answer: "A00 traveled 33 miles or 52 kilometers," he measured.

Next, to calculate flying speed in miles per hour, you need to divide the miles by the hours. Because you have 1 hour and 37 minutes, the first step is to put the minutes into hours. The 37 minutes are 37/60ths of an hour, or .61 hours, for a total of 1.61 hours. Dividing 33 miles by 1.61 hours = 20.49 miles per hour, for his average speed.

What Time Did A00 Travel?|
Discussion of Challenge Question #12

"Golden Eagle A00's first reading on March 19 was at 15:02 GMT, the second was at 16:39 GMT. What time was the eagle migrating (local time)? Give the two times the satellite caught A00 while his trip was underway, in local time."

Seventh graders Heather, Shana, Danielle, Ben and Dominick of Iselin Middle School, who live in the same time zone as the eagles, came up with the answer:

"Since we live 5 time zones from GMT we subtracted 5 from 15:02. The first local time for us was 10:02AM. The second time was 11:39AM. We subtracted 5 from 16:39."

Tip for Teachers: Visualizing the 24-hour Clock
Not only does the satellite give readings in GMT, it also uses the 24-hour clock. If this is confusing, here’s a helpful tip from Texas teacher, Jo Leland.
Turkey Dinner & Trophic Levels
Discussion of Challenge Question #10

When Biologist Scott Van Arsdale captured Golden Eagle A00, the eagle had been preying on a flock of over 100 turkeys. The turkeys, in turn, were feeding on grain picked out of the manure that the farmers had spread on the fields. Challenge Question #10 asked, "Starting with the sun, name the food at each tropic level that finally ended with turkey dinner for golden eagles on the dairy farm."

First some terminology: Ecologists call the path of food consumption a "food chain." Each level of consumption in a food chain is called a trophic level. (The word "trophic" comes from a Greek word meaning "to nourish.") To find an animal's place in the food chain, count the number of energy-transfer steps from the sun to the animal.

However, the food chain involving turkey dinner for our golden eagles is tricky. To solve the problem, you need to look carefully at the ENERGY in this system. Even though the cows ate the grain, some of the grain was not digested. It traveled right out of the cow into manure, and no energy was transferred. Energy-transfer wise, finding grain in manure is no different than finding grain on the ground. Therefore, the food chain looks like this:

Sun > grass (as grain in cow manure) > turkey > golden eagle

Try This! The Food Chain that Nature Built
The House That Jack Built
by Simms Tayback
Read the book "The House That Jack Built" to set your creative thoughts in motion. Next imagine a food chain, and illustrate each step. Finally, write a rhyme patterned after "The House That Jack Built" to show the chain of events that connects the trophic levels of your food chain.

Here is a sample food chain you can use (but it’s even better to come up with your own!)

  • The sun shone on a field and the grass grew.
  • A deer dined on the grass that the sun grew.
  • A mosquito bit the deer that dined on the grass that the sun grew.
  • A hummingbird ate the mosquito that bit the deer that dined on the grass that the sun grew.
  • A crow killed the hummingbird that ate the mosquito that bit the deer that dined on the grass that the sun grew.
  • A falcon swallowed the crow that killed the hummingbird that ate the mosquito that bit the deer that dined on the grass that the sun grew.
  • A cougar conquered the falcon that swallowed the crow that killed the hummingbird that ate the mosquito that bit the deer that dined on the grass that the sun grew.
  • The cougar died and a...

Niche of the Eagle's Favorite Fish?
Discussion of Challenge Question #13

We asked you to, "Explain what Peter Nye means when he says, 'The species (of fish) involved are not as important as the niche they occupy.' In your answer define the term 'niche'."

Sammi, of Mrs. Erdmann's class in Sutherland, Iowa, answered, "Niche, in my words, means bald eagles don't care about the species of fish as much as where they are."

Sammi’s got the idea! As long as the fish’s niche involves swimming near the surface where an eagle can capture it, the eagle doesn’t care what kind of fish it eats. In the words of an ecologist, a "niche" is defined as: "The role an organism plays in a community. How an organism interacts with the environment and other organisms." More simply put, an organism's habitat is its home, and its niche is its job.

Drawing a Tree’s Niche and Its Place in a Food Chain
One student’s answer helped us to think more carefully about the difference between an animal’s niche and its place in a food chain:

“A niche is a place in the environment or a spot in the food chain.”

Let's explore the difference: A food chain follows energy through a system. It begins with plants obtaining energy from the sun and involves predator/prey interactions. But organisms interact in ways other than to eat one another! And they also interact with the physical environment. Draw a tree and the interactions listed below to illustrate the tree’s niche. Only some of the interactions are part of the food chain. Put a star to show which ones:

  • A tree’s limb provides a nest for a bird.
  • A tree’s bark houses an insect during winter.
  • A woodpecker drums through a tree’s wood and captures an insect.
  • A tree’s roots absorb water from the soil.
  • A tree’s leaves gather sun and grow, through photosynthesis.
  • A tree’s leaves provide shade for a plant growing beneath it.
  • A tree’s leaves add humidity to the air, through transpiration.
  • A tree’s fallen leaves are eaten by a worm.
  • A tree’s branches serve as a highway for squirrels.
  • A tree’s highest branch is a perch for a hawk to sit and watch for prey.
  • A tree’s flowers are pollinated by the wind.
  • A tree’s seeds are eaten by a squirrel.
  • Add more ideas of your own!

How to Respond to Today's Challenge Question:

1. Address an e-mail message to:
2. In the Subject Line of your message write: Challenge Question #14
3. In the body of your message, answer the question above.

The Next Bald Eagle Migration Update Will Be Posted on April 9, 2003.


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