Bald Eagle Migration Update: March 10, 2004
Today's Report Includes:
Here's the Latest Data and Migration Map
Field Notes from Peter Nye
I wish I could give you some good news on our trapping efforts, but alas... Last week wasn't a lucky one for any of us. Scott, Kathy and I were out trapping several days, but no luck. Scott, who is after the golden eagle mate to A00 we are currently following, simply hasn't been lucky enough to have visits to his trap-site while he's all set up. The eagles have been visiting there fairly frequently, but just not when he's there! At about 17 hours per trap day, you just can't spend every day there waiting! Trooper that he is though, he is out there again this week for one last effort...keep your fingers crossed. For me, too. Although Kathy and I had a beautiful, adult bald eagle on our bait last week, our net mis-fired and we missed the bird. This happens once in a while.
Many factors have to all come together and work perfectly for a capture. Some folks think it is easy, just put out some bait and throw a net over them, but experience tells us otherwise! Kathy and I will be out for one last day tomorrow (Tuesday), and hope we can pass on some good news then. Meantime, keep monitoring these three birds and watch the NY weather!
Weather Maps: Treasure Chest of Clues
Think about these questions as you study the clues the map reveals to us:
Bookmark this weather map Web source:
To get the best “picture” of the weather for predicting eagle migration you will need a Canadian weather service. Try searching the Web and bookmark the best site.
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
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.)
Eating Out: Winter Dining Challenges
Read on to learn about this and more:
An eagle eats 5-10% of its body weight each day. Male bald eagles weigh 8-9 lbs., and females weigh 10-14 lbs. Sharpen your pencils and your wits for these calculations:
Eagle Head Adaptations: Discussion of CQ #10
The eagle's whole head is designed for its fishing and scavenging lifestyle. Last week you took a close look at their head and shared what you learned. Here are some of your comments:
Thanks to students Ruby, Lindsay, Jake, Ryan and Kris at Ferrisburgh Central School; Armand, Dominique, Slawomir, Danielle, Mike, Robert, Moaz, Chris, Jennie, Lauren, Michael H, and Gurjodh at Iselin Middle School; and Michael.
Read for more information about these adaptations.
Vision: An In-Depth Look at Eagle Eyes
Bird vision has impressed and baffled humans for centuries. Scientists consider bird eyes to be the finest in the animal kingdom. And raptors have the finest vision of all. Small wonder just about everyone knows the expressions "bird's eye view" and "eagle eyes"!
Get out your journals for a closer look at the marvelous form and function of the Eagle eye. This in-depth lesson holds the details for students who want to know more!
Bald Eagle Adaptations: The Tail
Are you ready for this week's adaptation?
An eagle's body is adapted for its fishing and scavenging lifestyle.
How to Respond to Today's Challenge Questions:
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