Peter Nye
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A/CPB
Bald Eagle Migration Update: February 23, 1998
Today's Report Contains
- Field Notes from Biologist Peter Nye
- Satellite Data from EASTERN Eagle (#F42)
- Challenge Question #3
- Conversation With Biologist Jim Watson
- Challenge Questions #4 & # 5
- Satellite Migration Data for WESTERN Eagles (#05, #12, #13, #16)
Field Notes from Biologist Peter Nye
To: Journey North
From: Peter Nye
Hi All, Conditions here remain extremely mild, with extensive open water everywhere, making it very difficult to attract eagles to bait. We were out trapping last Sunday (2/15/98) on our Hoosic River just north of Albany. No luck unfortunately, but had a beautiful adult golden eagle 1/2 mile upriver; a rare and gorgeous sight! We were down in southeastern NY trapping again on Tuesday (2/17/98). Unfortunately, again unsuccessful. We did have a beautiful adult bird "hit" our bait, but it grabbed it on the fly and never landed, so we were unable to trigger our power-snare trap.
It has been so mild here, in fact, that many of our eagles are already back on their nesting territories, adding sticks and "redecorating" their nests. No eggs yet, a little early for that, but our earliest pairs in western NY and southern NY may lay as early as the end of February.
Let's not talk nesting yet though, we are still firmly focused on wintering birds and captures. We still have four capture teams afield at four wintering sites around the state, and often, late February and early March are good for trapping as migrant birds begin to head north, and search out a quick, high-energy meal such as our deer carcass bait. We have not yet seen much in the way of early movements/migration; birds still seem to be in their wintering mode, as evidenced by F42, the adult we have been tracking around the lower Hudson River since mid-December, who is still within her wintering territory. Of course, with F42, we face the same question we face each year when we capture an adult bird in winter; is it a migrant or could it be a local nester we didn't know about? Of course we hope it is a migrant since we have put a very expensive satellite radio transmitter on it! Time will tell.
As mentioned in my last report, #N98 and #N99's transmitters are losing battery power, thus we are getting fewer and poorer quality 'fixes'. I'm not sure what is up with N98. She seems to have remained just north of her St.Lawrence River capture site, still in Canada, with little movement. Makes me wonder if the transmitter is off her, or if she is dead and on the ground somewhere. We'll just keep monitoring the signals and see what happens.
That's it from NY for now; keep your fingers crossed!
Eagle Eye Nye New York Department of Environmental Conservation
Today's Satellite Migration Data from EASTERN EAGLE
Challenge Question # 3
Using all satellite data between December 31st and February 18th, plot the winter range of # F 42. Then see if you can answer this question:
Challenge Question # 3
"According to satellite data from #F42, how large is this eagle's winter territory?" (You may give your answer in square miles and/or give the names of the towns which mark the edges of her territory.)
To respond to this question, please follow the instructions at the end of this report.
Conversation With Biologist Jim Watson
JOURNEY NORTH:
In our last report, you were surprised by the data from one of your eagles and said, "This is a new movement
pattern for all birds captured thus far." We asked students as Challenge Question #2 which eagle you might
have been referring to, and where that eagle went. Could you comment on the significance of this eagle's travels?
JIM WATSON:
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Crossing over the Cascades |
At the time I wrote this no birds from this season had moved into eastern Washington. One eagle did last season. Since that time, 2 other birds moved into eastern Washington. We also have one bird on the Sacramento River in northern CA. (Not one of the 4 students are tracking.) The Sacramento is a chum salmon river. It will be very interesting to see where this eagle moves.
JOURNEY NORTH:
What can you tell us about the natural history of the chum salmon that span in the Skagit River? From how far out
in the ocean have they returned? How long do they stay? How old are the fish when they spawn?
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Jim Watson's sons Cory and Jesse with eagle bait. (King or chinook salmon on left, coho or silver salmon on right.) |
JIM WATSON:
Chum salmon spawn on the rivers of Puget Sound from early November through mid-December, and the carcasses float
down the rivers and onto the river bars through January. By February all the carcasses are gone, except for a few
in the backwater areas. A few coho salmon carcasses, and spawning steelhead are also in these areas. Right now,
only 2 of the telemetered eagles are in the vicinity of their capture locations on the river. Most of the eagles
are now gone from the upper Skagit River.
The adults that spawn have returned from the ocean where they have lived from 3 to 5 years, as far away as the Arctic Ocean (over 1000 miles). When the Chum salmon eggs hatch in the spring and early summer, the young move to the ocean, about 25 miles away (Puget Sound).
JOURNEY NORTH:
Is the chum salmon population healthy, or is it experiencing declines?
JIM WATSON:
Last year some volunteers working for me counted over 1000 carcasses the first week of December; this year they
counted only about 100. This year was especially low, primarily since this was an "off" year. (Chum run
is low in odd-numbered years compared to even-numbered years.) Long-term trends for all salmon on the Skagit River
are downward, but less so for chum salmon.
Perhaps the biggest reason for lower Chum salmon numbers goes back to river conditions in the late winter and spring 3-5 years ago when the generation of adult fish was hatched. High river levels, and too much water at that time could have flushed out eggs from spawning redds and resulted in fewer fish being hatched, and fewer adult returning to the river this year. In addition, siltation of spawning redds from extensive logging on the river, and overfishing in the open seas is also be contributing to reduced numbers of chum and other salmon.
JOURNEY NORTH:
As you mentioned previously, one purpose of your research is to assess the impact of human disturbance. Have human
uses of the river been significant this year, and how have eagles responded?
JIM WATSON:
The primary recreationists (besides eagle watchers) are the steehead fishers. Both bank and river fishers seek
this prized fish (anadromous rainbow trout) throughout the winter. Because the steelhead population was so low
(like the salmon), the river was closed to fishing for steelhead in December, and just reopened in February. Consequently,
there were few fishers on the river this winter and we observed very few eagle/recreationist interactions.
JOURNEY NORTH:
And now some questions for students!
Challenge Question # 4
"How tall are the Cascade Mountains over which eagle #13 flew?"Challenge Question # 5
"According to today's migration data, where was each of our 4 eagles on the latest date shown?" (Give the name of the town nearest to each bird.)
To respond to these questions, please follow the instructions at the end of this report.
Today's Satellite Migration Data from WESTERN EAGLES
How to Respond to Today's Bald Eagle Challenge Questions
Please 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 # 3 (or #4 or #5)
3. In the body of the message, give your answer one Challenge Question (# 3 or #4 or #5).
The Next Bald Eagle Migration Update will Be Posted on March 9, 1998.
Copyright 1998 Journey North. All Rights Reserved.