Bald Eagle

Bald Eagle

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Western Bald Eagle Migration Update: February 10, 1999

Today's Report Includes:

Field Notes from Biologist Jim Watson

To: Journey North
From: Jim Watson

Dear Students,
I am conducting a wintering study of bald eagles on Washington's Skagit River. This river, and its tributaries, support up to 500 eagles that feed on chum salmon from November through February. These salmon spawn on the upper river and their carcasses wash onto gravel bars where the eagles congregate to feed.

During the same time, recreationists congregate on the river to fish for steelhead (a large rainbow trout) and watch the eagles. Because of potential concerns for disturbance of the eagles from these activities, the U.S. Fish and Wildlife Service, Forest Service, and Department are funding a study to determine where these eagles come from, how long they survive, and if their nesting populations are healthy.

The research began in 1996, and will continue through the end of 1999. To determine where the eagles come from, we are using satellite telemetry that allows me to retrieve the locations of the eagles right from my computer--within an hour or two of sending a signal, I can tell where the eagles are several hundred kilometers away! There are also small VHF transmitters on the eagles that allow us to follow them on the river or locate them if they should die.

As always, my wife and sons, 12-year old Cory, and 10-year old Jesse, often assist me on the study (see photo). Its hard to believe that these "fledgling scientists" are at the age when I was 25 years ago when I became interested in raptors--perhaps someday they will be "fully-fledged" raptor scientists!

This winter trapping was considerably more difficult in December and through mid-January compared to previous winters. Chum salmon carcasses were very abundant and we had milder weather. Also, because the birds were somewhat stationary, we were working with the same birds so they get trap-shy pretty fast. By mid-January the eagles began to find fewer carcasses and our bait began to look more attractive

We've completed trapping now, and have captured 41 eagles for the study. Twenty-six eagles have satellite transmitters.

I'll be sharing satellite data from 2 birds with you:
Eagle #18: Our first capture of the season, an adult male on 01/22/99.
Eagle #12: An adult female captured 12/5/97 and tracked through
Journey North last spring. Eagle #12 turned out to be a migrant that went
to southeast Alaska in July. As such, she is an interesting individual to

Jim Watson
Washington Department of Fish and Wildlife

Challenge Question #3: Wandering Around Washington?
Today's migration data are provided below. Plot each eagle's locations on your map, and see if you can answer this question:

Challenge Question #3
"Which eagle seems to be wandering around Washington? If you plot this eagle's movements since January 21 or 22, how many miles has it traveled? The students in what town might have seen it, if they looked overhead on Sunday, February 7?"

Today's Migration Data

(To respond to this question, please follow the instructions below.)

Comparing Migration Year to Year, Season to Season
Spring & Fall Migration 1998
This map shows the round trip migration of Eagle #13, during all of 1998. Analyze Eagle #12's Fall, 1998 data and try to figure out why this eagle is traveling when and where she is!

Keep an eagle eye on this bird and maintain this migration chart so you can compare 3 season's migrations:

How to Respond to Today's Challenge Question

1. Address an e-mail message to:
2. In the Subject Line of your message write: Challenge Question # 3
3. In the body of your message, answer the question above.

The Next Bald Eagle Migration Update Will be Posted on February 24, 1999.

Copyright 1999 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form

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