Bald Eagle

Bald Eagle

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Bald Eagle Update: February 6, 2001

Today's Report Includes:

Welcome Back to Biologist Peter Nye
We welcome the return of "Eagle Eye" Nye who's back for the 8th season! Nye is one of the top eagle biologists in the nation, and we're grateful for the chance to look over his shoulder each year as he conducts his important work.

Nye was a pioneer in re-establishing eagles after their decline caused by DDT. As you probably know, the chemical DDT made egg shells so thin the young couldn't hatch. This nearly eliminated Bald Eagles throughout the lower 48 U.S. States. By 1976 for example, only one pair of eagles was still attempting to nest in the entire state of New York --and that nest failed.

Photo: USFWS
That same year, Peter Nye developed a way of raising young eagles known as "hacking." Nye and his colleagues went to Alaska, where eagles were still abundant, and gathered young. Like foster parents, they raised the young eagles back in New York in "hacking towers" until the eagles were old enough to fly. Slowly but surely, year after year, the population has continued to build and there are now 51 nesting pairs of Bald Eagles in New York!

Nye is also a pioneer in the high-tech migration tracking method called "satellite telemetry." We join up with him as he begins another year of research, preparing to outfit eagles with "satellite backpacks" and track their spring migration.
Field Notes from Eagle Eye Nye

Hi Kids,

Bald Eagles
at Nye's Bait


Wintering Range Map

Our annual winter-trapping is underway! We have five new satellite radios to deploy this spring, so we will have as many as five new birds "on-line" this year, plus the 5 birds we tracked last spring. (See map at right and data below.) Although we are focusing our research on movements of wintering bald eagles--into and out of New York State--we are always on the look-out for golden eagles. They occur much more rarely here, and if we happen to capture one at a bait station, it would be a great opportunity to learn something about that species' movements. So don't be surprised if we start tracking a golden eagle, too!

The Season's First Surprise
My colleague Blanche Town caught our first adult Bald Eagle last Tuesday, January 30th on the St. Lawrence River. We were both very excited. Because the eagle was already banded, before putting a satellite radio on it, just for safety's sake I ran a check in my "eagles-banded" data base (now containing about 800 entries), I turned up some even more exciting news:

It turns out that this eagle was one of the first two eaglets we hacked (reared and released) in the world's first eagle-hacking effort, here in New York in 1976. This bird became the foundation of our expanded eagle restoration program (and many other states' as well) when she began breeding 4 years after release, in 1980. We know where she has been breeding (at least we think it is still her at that site), which is not far from the St. Lawrence River, so no need to put a satellite on her. It is very interesting to know she is alive and well after 25 years in the wild! I took a blood sample which will also be of great interest, to see what type of contaminant build-up she might have after 25 years in New York.

Counting All Eagles: Annual Mid-winter Bald Eagle Survey
We conducted our part of the National Mid-Winter Bald Eagle survey on January 10 & 11, with several aerial flights and ground-observers out there counting the total number of wintering eagles we have in the state. Our winter has been much colder than normal and much ice has built up throughout the state, concentrating our eagles in their usual winter habitats. Last year during this survey, we counted 350 bald eagles in New York. Amazing! Especially when you consider that when I started doing these surveys in 1978, our totals were in the 20's! Students may want to graph the comeback of bald eagles using the data we've collected:

So we're off to an exciting start. Stay tuned, as we hope to have captured some new eagles by the next update.

Eagle Eye Nye
New York State Dept. Environmental Conservation
Delmar, NY

Why Count Manatees, Monarchs and Eagles in the Winter?
Here at Journey North, we hear from scientists studying the migrations of all kinds of creatures. This year we noticed that Florida's Manatees, Mexico's Monarchs and the United States' Bald Eagles were all surveyed at the same time. It's fun to picture why: The cold causes all of these animals to aggregate. (Do you know why each species aggregates where it does, when temperatures are cold?)

Peter Nye says New York's eagle counts are always sure to be the highest in January.

Challenge Question #1:
"Why do you think more bald eagles are found in New York during the winter months than at any other time of the year?"

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

Challenge Question #2: How Can an Eagle Catch a Duck?
In our next update, Peter Nye will describe the hunting techniques eagles use to catch fish and other prey. "Fish make up over 90% of the eagles' diet at our largest wintering area in Southeastern New York," says Nye. "At one of our smaller areas, along the Hudson River north of Albany, waterfowl makes up more than 75% of their diet."

How can an eagle catch a duck? Most waterfowl migrate at speeds of 40 to 60 miles per hour, and average about 50 mph. They can go even faster when being pursued by a predator. (A Red-breasted Merganser was recorded going 100 mph in Alaska, where it was being chased by an airplane!) Bald Eagles have been clocked at 35-44 mph, 30 mph when lugging a fish. Thus, catching a duck for dinner sounds like quite a challenge, in fact it makes you wonder:

Challenge Question #2:
"How do you think an eagle can catch a duck?!" (Describe the eagle's hunting technique carefully.)

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

First Satellite Data from Eagles K58, K70, K72, F43, F81

Wintering Range Map
In our February 20th update we'll discuss the term "wintering range." To prepare, plot the latest satellite data from each eagle on your map as shown above.

Backtracking: Fall 2000's Journey SOUTH
Students with extra time and interest can investigate the fall migration patterns of our five eagles.

Tips for Teachers: Are YOU Ready for the Migration?
Our satellite-tracked eagles typically begin to migrate in March. Depending on the age of your students, the skills you want to teach (and your own comfort level with satellite data!), you may want use the migration data in various different ways. Here are some tips and background lessons to help you get ready:

Make Your Own Migration Map, Or Print and Analyze Ours
The satellite data provides an excellent exercise in use of latitude and longitude, and plotting the data develops students' mapping skills. In each update, we wprovide the same data points that Peter Nye receives from the satellite. However, if mapping is too difficult or laborious (or if it simply doesn't meet the skills your students are learning), you can skip the mapping step completely and simply print out our weekly maps for analysis. Our Challenge Questions usually refer to the interpretation and analysis of data, so even if students do not make their own maps, they won't miss this important component.
  • Latitude, Longitude and Distance Traveled

    This lesson will help you get comfortable with satellite data, so you'll have a feeling for the distances involved when an eagle's latitude and longitude readings change.

  • How to Map Satellite Telemetry Data

    This lesson includes charts with step-by-step instructions for pinpointing an eagle's latitude and longitude on a map. By putting a transparency on top of your map, an eagle's exact location can be more easily found.


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 # 1 (or #2).
3. In the body of EACH message, answer ONE of the questions above.

The Next Bald Eagle Migration Update Will Be Posted on February 20, 2001.

Copyright 2001 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form

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