Eastern Bald Eagle Migration Update: May 5, 1999
Today's Report Includes:
Pete Nye's Laptop Out of Order
We've been so busy tracking migration this spring, you've probably never thought
about how the EAGLE DATA travels to you each week! Here's the path:
- The eagle's transmitter sends signals to ARGOS satellites above the earth.
- The satellites send the data to the ARGOS computer near Washington, D. C.
- The Washington, D. C. computer sends it to Peter Nye's laptop in New York.
- Pete Nye sends it to Journey North Headquarters in Minnesota.
- From there, we send it to our staff members who all work in different places around Minnesota.
- When the report is done, it goes BACK to Washington D.C., to the Annenberg Media computer called "Learner.org."
- The computer at Learner.org sends it to you!
This week Pete's computer is out of order, so there are no data for you. But isn't it amazing you ever get it,
when you think about all the places it could get lost!?
Do Male and Female Eagles Migrate Together?
A few weeks ago, Peter Nye tried to predict where male Eagle #F81 might nest. He said: "This is a bit hard
to predict since we've never tracked this adult male eagle before. But, based upon his early departure date and
latest movement behavior, I'm going to guess that he is going up into Labrador at about 52.600N, -65.900W. Which
brings up a related question:"
"Do you think males or females arrive back at their nest site first; why? Or, do you think they migrate
together?", asked Challenge Question #20.
Here are Eagle Eye Nye's observations:
"Many questions surround bald eagle migration, some involving
male versus female behavior. Although we have only a couple of complete 'stories' to go on, from the work we've
done over the past decade or more it appears that males and females migrate back to their nest sites separately.
"We have tracked males back to their nest sites, and found that they arrive there first and alone, with the
female following some days or week or more later. Why they may not travel together and why the male may generally
get back to the nest site first (if that is indeed mostly the case), is unknown.
"From extensive work we have done here in New York during our eagle release program many years ago, we know
that the males are typically the ones who establish the nesting territory in new territories. So, it is possible
that the males want to 'get back' to these prime nesting spots first, to 're-claim' and defend them, and wait for
their female or another female. Perhaps the females are not in as big a hurry (or need) to get to a nesting site,
as they are a valuable commodity and can 'slip' into one pretty quickly.
"Another good question involves how 'pairs' overwinter,
which is a somewhat linked question to the migration one. During the winter, we can sometimes identify what are
obviously breeding pairs hanging together, but I would have to say this is more the exception than the rule. Again,
birds we have had radio marked have, in most cases, spent their time on the wintering grounds alone, then migrating
alone, as if they don't have a mate. We do not yet know if mated pairs usually over-winter together or even at
the same wintering spots. As I said, some do, but it would seem that for most we cannot say this. We would have
to capture both males and females from the same pair to find this out. So, as you can see, there is lots yet to
learn about eagles, migration, mated-pairs, and, and, and !!!!!"
Peter E. Nye
New York State Dept. Environmental Conservation
Division of Fish, Wildlife and Marine Resources
The FINAL Bald Eagle Migration Update Will be Posted on May 19, 1999.
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