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Bald Eagle Migration Update: March 19, 2003
Today's Report Includes:
- Field Notes from Peter Nye: Migration About to Begin!
- Ready for Take-off? March is Migration Month
- They Scored! Season's Second Golden Eagle Now Online
- First-hand Account of A00’s Capture by Scott VanArsdale
- Challenge Question #9
- Turkey Dinner: Name the Food at Each Trophic Level
- Challenge Question #10
- Instructional Strategy Spotlight: Chain of Events
- Do Mated Pairs Over-Winter Together?
- Discussion of Challenge Question #8: Weight of Satellite Backpacks
Field Notes from Peter Nye: Migration About to Begin!
“Ok boys and girls, day to day now! Spring is definitely in the air, and the daylight is longer each day. These are good days for birds to catch thermals and head north! The latest data confirms that at least E47 has begun to move north now, and it looks like E49 is getting the bug too! Note her slight northeast move here...”
Link to Latest Data:
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Ready for Take-off? March is Migration Month
When do you predict the eagles will take off? Below are the dates by which each eagle had taken off last spring (meaning the first jump north had occurred by this date). Other than these dates, upon what else might you base your predictions?
- #E47: March 26
- #E49: March 16
- #E50: March 30
- #E63: February 20
- #V31: (Not online last spring.)
- #A20: April 15
- #A00: (Not online last spring.)
They Scored! Second Golden Eagle Now Online
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| Scott with A00 |
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| Can
you see the blue stiches that connect the 4 straps of the satellite
backpack? (Click to enlarge.) |
| Count the challenges Scott faced before finally catching this elusive golden eagle. |
| Golden Eagle Facts |
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| Kathy Michell with Scott |
"Guess what we got a hold of last Tuesday?, began Peter Nye. "Persistence through the cold and long hours finally paid off for our eagle folks, Scott VanArsdale and Kathy Michell. They successfully caught one of the two golden eagles we've been after (Scott has been after, mostly!) for over a month now.
"This is an adult golden eagle, one of a pair that have reportedly been wintering in this area of New York State for several winters now. A00 appeared to be a small bird, and we guess it may be a male. We outfitted A00 with leg bands and two radio transmitters, a satellite "PTT" and a conventional "vhf" transmitter that will allow us to track it at close range should we need to or want to, such as if we visit its nesting site. It bears a black NY leg band "A00.” (Black is the band color we use on golden eagles in New York).
This is only the 3rd golden eagle we have outfitted with a satellite transmitter, and the first full adult (although we have caught about a half dozen more goldens over the years during our winter eagle work). Both of the previous satellite-tracked eagles have gone to Labrador. Do you think this one will also? Take a look and see where A20, our other golden eagle, has been all winter, and where it went last spring and summer. It should be leaving and heading north any day now. We are anxious to learn when A00 takes off, and if it does so with its suspected mate.
One interesting, and perhaps troubling, issue with A00: When captured, we observed he only has one of his four toes on the right foot. He is missing his hallux talon (the rear, forward-facing talon) and two of his front toes. These are old injuries, as they were well-healed, and apparently this bird has been able to survive a while with only one working foot and set of talons. This is obviously a huge drawback to a bird that survives by actively capturing and killing live prey. This must also affect his perching ability.
However, he was in good flesh (not emaciated), so we hope he survives for a good many more years. I suspect this injury is a result of being caught in a leg-hold trap, an injury we've seen before in raptors and in both species of eagles. This is just my gut reaction, but I got the feeling this was not a young bird, and may indeed be a bird that has been alive for many years. Unlike the traps we sometimes use to capture eagles, which are padded and have off-set jaws, most trappers' traps are unpadded steel and the jaws come fully closed together. The result is severely damaged toe-tissue, often resulting in the toe falling off. The lucky raptors' toe-stubs heal over; the unlucky ones die of systemic infection. Eagles and other raptors are attracted to trap-sets either because another animal is caught, and upon investigation the bird gets caught in another trap, because there are often multiple traps in a given set. Or, some trappers use what are called "open-bait" sets, where meat or some other animal attractant is purposely placed at the set, visible to visual-hunting raptors who come down to investigate, walk around and get caught. Such open-bait trapping was proving to be such a problem in some states with eagles, that the practice has been banned."
Eagleye Nye
First-hand Account of A00’s Capture by Scott VanArsdale
Special thanks to Scott VanArsdale for sharing this story of the trials and tribulations leading up to A00’s capture! Read the details, then see if you can answer Challenge Questions #9 and #10:
Challenge Question #9:
"List all of the steps Scott took, and the challenges he faced, before finally capturing Golden Eagle A00."
(To respond to this question, please follow the instructions below.)
Turkey Dinner: Name the Food at Each Trophic Level
In reading Scott's description of the Golden Eagle's prey, we're reminded that nothing is wasted in nature.
Challenge Question #10:
"Starting with the sun, name the food at each tropic level that finally ended with turkey dinner for golden eagles on the dairy farm."
(To respond to this question, please follow the instructions below.)
Instructional Strategy Spotlight: Chain of Events
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Do Mated Pairs Over-Winter Together?
In today’s report, Peter Nye says he thinks the two golden eagles are a mated pair. We asked, "Is it known that golden eagle pairs over-winter together? What evidence makes you think the goldens are a pair?"
Pete Nye: My observations over the years have led me to the conclusion that the vast majority of over-wintering eagles do not over-winter as pairs. However, that is not to say I've never seen it nor that it doesn't occur. I have seen what I believe are mated pairs in winter, in both bald and golden eagles. I don't think anyone knows enough about either species, especially goldens, to say for sure. But, in this case (our Delaware County birds), and in another case with goldens here in New York (a pair that have been overwinteriing together in Dutchess County for probably 15-20 years), it certainly appears they are a mated pair: My reasoning: In each case there are no other birds in the vicinity, just the two, and they are always together.”
- Think About This: For what reasons might mated pairs over-winter together? Why might they over-winter apart?
Discussion of Challenge Question #8
Weight of Satellite Backpacks
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Seventh grade students Jay, Tomas, Jonathan and Dipesh at Iselin Middle School said, "We used a team mate who weighs 120lbs. We divided 120 by 100 and multiplied by 2. The backpack would weigh 2.4lbs. We then converted to grams. Since 1lb. = 453.59 grams, a backpack weighing 2.4lbs would weigh 1088.616 grams."
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 #9 (or
#10).
3. In the body of EACH message, answer ONE of the questions above.
The
Next Bald Eagle Migration Update Will Be Posted on March 26, 2003
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