>
Your robin migration map isn't complete yet! Here's one more sighting to add: According to students in Homer, Alaska robins came home on April 25th. Pull out a map of Alaska and reconstruct the robins' trip. According to Mike Sterling at Sand Lake Elementary in Anchorage, he and his students all suddenly saw their first robins on the 29th.
Date............Location
April 24........Glenallen, Alaska
April 25........Homer, Alaska
April 29........Anchorage, Alaska
After viewing the robin migration map in our last report, a few people contacted us with corrections. We're now constructing a final map and will incorporate those changes.
In our next and final robin migration update (May 21) we'll focus on robins' favorite food, the earthworm. In the meantime, send us any questions you may have about worms and we'll dig until we find the answers.
Thanks to students in Washington, Colorado and Wisconsin for answering Challenge Question #95 ("Exactly how was DDT getting into the worms robins were eating?"). They did a wonderful job researching this complicated mystery.
If you dig a little deeper into the subject, you'll find that robins don't actually eat dirt. Rather, they eat food that's found in the dirt. This seemed to be a common misconception. According to Rachel Carson's book, Silent Spring, it was by eating contaminated leaves that DDT built up in the worms' bodies. The contamination trail was a long one; the story went like this.....
The robins ate worms,
which had eaten leaves,
Which had fallen from trees,
which had been infected with a disease (called Dutch Elm disease)
which people had sprayed with DDT.
Of course DDT was used as an insecticide in many other instances, in addition to Dutch Elm disease. However, the Challenge Question referred specifically to the discussion in Chapter 8 of Rachel Carson's book, Silent Spring.
If you're squirming at your desk, eager to go outside and enjoy the warm weather, here's the perfect Challenge Question for you:
Challenge Question # 109
"How many worms live in a square foot of soil in your part of the world?"
Try This!
1. Calling All Worms
Go outside, get down on your hands and knees, put your face about 6" from the ground, and search for worms
just as a robin does. Can you see any? According to a news article by Sy Montgomery in the Boston Globe, "Worms
tend to nap with their tails protruding slightly from their burrows." If you were a real robin, you'd better
be good at this because according to Montgomery, "Baby robins need 14 feet of worms a day.!" Remember,
robins don't dig for worms so it's not fair to use your hands.
2. Sample the Soil
Dig a hole that measures 1' x 1' x 1'. As you dig, put all the soil on a large piece of plastic. Using your hands,
dig through the grass, leaves or other vegetation in the soil and hunt for worms. Count the number in a your cube
of soil and answer Challenge Question #109 above. Are all the worms the same size? How deep in the ground are most
of them found? Measure your school yard. If you were to count all the worms there, how many do you estimate you
would find?
3. Observe a Robin's Feeding Behavior
At what time of day are robins found on the grass looking for worms? In what weather? Are they on the grass more
often when it's wet? How many minutes does it take a robin to find a worm? Does it eat the worm immediately or
fly away with it? Do you see it eating anything else?
Students Responses to Challenge Question # 95
From COLORADO:
Many people sprayed D.D.T. pesticide all over the ground, the D.D.T. spray got into the soil and that was where
the worms were. When the worms ate the soil that had been sprayed, they would become infected. When the robins
got hungry they would eat the worms and they would become infect by the D.D.T. spray. There for when the robin
layed their eggs the eggs would crumble and break because their body wouldn't get as much protein, so the eggs
wouldn't have as much protein. V. White (vivwhite@limestone.kosone.com)
From WASHINGTON:
The farmers were spraying the weeds with DDT. The DDT got into the ground. Worms eat the dirt so, robins eat the
worms with DDT. Then robins get sick and die. And thats how DDT got into Robins.
Grade 3 student, Fall City, Washington
joelle_keizer@quickmail.snoqualmie.wednet.edu
From WISCONSIN:
We are Jerry, Mark, Ryan, and Dan from Drummond, WI. We are in 7th grade and we think the answer to Challenge Question
95 is the DDT was getting into the worms because it breaks down very slowly in the soil. Then when the worm eats
the soil it gets into the worm and when the robin eats the worm it gets in to the robin.
Mary McHugh (marymath@logger.dasd.k12.wi.us)
ROBIN REPORTS FROM FIELD OBSERVERS
Date................Location
04/24/96..........Glennallen, AK (62.20 N, 145.866 W)
04/25/96..........Homer, AK ( 59.3833 N, 151.3254 W)
From ALASKA:
April 24, 1996
It was sitting on a stump, at aproximently 6:30
Beau Dean Sawyer
Mr.Szarzi
62 12' N/ 145 52' W Glennallen Jr.High, Glennallen, Alaska
jszarzi@igc.apc.org
From ALASKA:
April 25, 1996
Our first robin arrived on Thursday, April 25. We watch for the arrival of the varied thrush. It arrived only a
week earlier but usually come much earlier than robins.
Thanks, Anna and Renae
Homer, Alaska
(Kachemak Bay, on Cook Inlet)
Homer Intermediate School Orca, orca@alaska.net
The Final Robin Migration Update Will be Posted on May 21, 1996
|
|
|
|---|
