 |
|
||||
|
Bald Eagle Migration Update: April 9, 2003
Today's Report Includes:
- This Week's Migration Map and Data
- Try This! Do You See What the Scientist Does?
- Field Notes from Biologist Peter Nye
- What's the Weather Like in Labrador? Challenge Questions #15 and #16
- Weather Forecast By a Bird? Discussion of Challenge Question #14
- Birds and the Built-in Barometer
- Try This! Watching Barometric Pressure and the Weather
- Reading Strategy Spotlight: Paraphrase/Retell
This Week's Migration Map and Data
Link to Latest Data:
Try This! Do You See What the Scientist Does?
Before reading Peter Nye's comments below, about each eagle's progress, look at the migration map and describe what you see. (For simplicity, print last week's map and compare it to this week's.) How do Peter Nye's notes compare to your own observations?
Field Notes from Biologist Peter Nye
Hey all,
Lots of progress to report this week!
- Adult female Bald Eagle E47 appears to be home! Prior to the fix on April 4th, our last fix on her was on March 25th when she was still in transit. Then, apparently, her PTT kicked in to its "on-cycle" only once every 10 days. Hence by the April 4th fix--viola--she'd already made it home!
- Looks like our new adult male Bald Eagle V31 has decided he likes it up there along the White River in Vermont. He's been hanging there a week now...Do you think he'll stay there. Or travel some more?
- Unfortunately, it looks like battery voltage on Bald Eagle E49 is dropping and maybe the transmitter is (excuse the expression) Petering out. No usable signals on her since March 29th. (We've marked the map to show where her nest site was last year so you can see where she's probably headed.)
- Adult male Bald Eagle E50 is still hanging in here...Last year he took off sometime between April 14th and 16th, and headed straight to Labrador. What day will he take off this year? How long will his travels take? Stay tuned!
- A big northeast jump for Golden Eagle A20 on April 2nd and another big move on the 5th. Where was A20 last year at this time? How do the two spring migrations compare?
 |
 |
| Last Spring | This Spring |
- And now the one you've all been waiting for! Adult Golden Eagle A00 was still trucking north and east on April 1st and 4th. Then dropped back to the southwest a bit on April 6th. Searching maybe? Where will this eagle land?
Until next week,
Eagleye Nye
What's the Weather Like in Labrador?
Challenge Questions #15 and #16
 |
NOAA
Satellites and Information |
Challenge Question #15:
"According to the map, what were the snow and ice conditions like in Labrador on Monday, April 7?"Challenge Question #16:
"What are typical high and low temperatures in April in Labrador? (When you respond, please tell us where you found temperature information.)"
(To respond to these questions, please follow the instructions below.)
Weather Forecast By a Bird?
Discussion of Challenge Question #14
Last week, Pete Nye said Golden Eagle A00 might have traveled on Sunday to try to get ahead of Monday's coming storm. Challenge Question #14 asked, "Do you think it might be possible for an eagle to forecast the weather? If so, how?"
Congratulations to Michelle of St. Wendelin School for suspecting eagles have a weather station on board: "They may be able to sense changes in barometric pressure so they know when weather fronts move in."
Birds and the Built-in Barometer
Scientists have long noticed that birds feed intensely as air pressure falls. They apparently have an inborn barometer that is extraordinarily sensitive. This is a handy adaptation for all birds, even non-migrants, because storms usually are associated with falling pressure, and birds have a hard time getting food during a storm. The sooner they can predict a storm before it hits, the more time they have to prepare.
Recognizing air pressure is also handy because birds often migrate along frontal systems, and changing air pressure is one of the first signs that a front is coming. Just as low pressure indicates storms, high pressure systems typically have clear skies. Thus, sensing if air pressure is rising or falling would enable a bird to anticipate changes in weather.
Scientists also have known for a long time that migrating birds fly at different altitudes than non-migrating birds, and maintain this altitude even on moon-less nights when they can't see the ground at all. How do they maintain a particular altitude? Many scientists suspect that this is also due to their ability to "feel" air pressure. Studies have shown that birds are extremely sensitive to small changes in air pressure, comparable to differences of only 5 to 10 meters in altitude. (Atmospheric pressure is lower at higher altitudes. If measuring with a barometer, pressure is lower by 1 cm for every 100 meters of altitude.)
How do birds judge air pressure? Scientists don't know!! They do have a couple of guesses. One is that birds may be able to detect it through their inner ear. We detect large changes in air pressure in our own inner ear when we make a fast change in altitude--that's when our ears "pop." Another guess is that the birds detect air pressure somehow though the huge air sacs that connect to their lungs and fill much of the space inside their bodies.
Try This! Watching Barometric Pressure and the Weather
1) Watch how barometric pressure changes with the weather. Record the barometric pressure over a period of at least 3-4 days. (Take a reading regularly, as often as 3-4 times during the school day. Ideally students could also be assigned to keep these records during off-school hours for these 3-4 days.) Tip: Keep your eye on the weather map! Try to time this activity when a storm is approaching.
2) After observing how pressure changes over time, study weather maps and track high & low pressure systems, and their associated wind directions and fronts. Try to do this for a week or two, to see the patterns.
3) How could you build a tool to help you measure air pressure? Discuss how a barometer might be designed--or actually build one! (A Web search will result in links to many samples and instructions.)
Reading Strategy Spotlight: Paraphrase/Retell
 |
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 #15 (or
#16).
3. In the body of EACH message, answer ONE of the questions above.
The
Next Bald Eagle Migration Update Will Be Posted on April 16, 2003
Copyright 2003 Journey North. All
Rights Reserved.
Please send all questions, comments, and suggestions to our feedback form
