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American Robin Migration Update: March 7, 2000

Today's Report Includes:

Today's Migration Maps and Data
FIRST Robins and WAVES of Robins
Reports of migrating robins continue to fly into Journey North headquarters! Here are 62 new sightings to add to your migration map:

Now you may not think this map shows a meaningful pattern--but think some more: For example, what DOESN'T the map show that you might have expected? Plan to compare robin migration with that of another species, such as monarchs, loon, hummingbirds or orioles. Then revisit your robin map and describe the picture you see, comparing and contrasting with the map of another migratory species.

Don't Forget!
Please report to Journey North the first robin you SEE, the first robin you HEAR singing, and WAVES of migrating robins.

Robins Reach Home
Dates Robins First Heard Singing

During the past week, twenty home-town robins were greeted by Journey North observers in these locations.

Compare the pattern on this map to the one above. Why do you think they are so different?

Announcing JN's 2000 Early Bird Contest!
How long will it take robins to reach the end of the road? Once again this spring, students at Sand Lake School in Anchorage, Alaska will officiate our annual Early Bird Contest, and you're invited to predict when the first robins will be seen in Anchorage. To enter the contest, simply answer this question:

Challenge Question # 3:
"When do you think the first robin will be spotted in Anchorage, Alaska (61.22N 149.90W)?"

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

Hello, Sand Lake School in Anchorage!

Meet the students officiating the Early Bird Contest. Mr. Sterling and his class wrote these clues about their winter. See why they're so eager to spot their first robins!

Dear Journey North,
This has been a very unusual winter. We get warm weather with very high winds and then cold weather. Our teacher lives high in the mountains and says that he gets wind up to 100+ miles per hour. This winter has also been wet and very icy.

This winter many highways have been closed by avalanches. At our main ski resort there have been several avalanches that have closed down the mountain.
With all this bad news the good news is we are getting more daylight. The increase per day is five minutes and forty five seconds.

Mr. Sterling's class

Sand Lake teacher Mike Sterling added this hot-off-the-press news:

"Our pussy willows are out early again this year. The entire month of February has felt 'springy' in the Alaskan sense. High temperatures have frequently hovered in the low 30's, and we've had some days rise as high as the 40's."

The Early Bird Gets the ______ ?
You probably said worm, right? But an early bird also gets. . .the best territory!

Male robins generally choose the nesting territory (the place where mating and nesting occurs), arriving there before the females. The older experienced males are usually the first to arrive and claim nesting territories. The inexperienced males must settle for second-best sites, which explains the chasing you may see among robins in early spring. Nationwide, banding returns show that about 74 percent of robins return to within 10 miles of their birthplace. Both males and females generally return to the same territory. Together, a male and his mate will defend their breeding territory until fall, while sharing common feeding grounds on nearby lawns, golf courses, cemeteries, pastures, and parks. A robin's territory is usually less than half an acre. (An acre is about the size of a football field.) How could you map your robin's territory? Find out at Journey North's:

Why is a good nesting territory so important to a robin? First, robins need safe places for building nests and laying eggs. After the eggs hatch, the territory has to provide food not only for ravenous nestlings, but for the parents as well. In our last report, we said each young robin may eat 14 feet of earthworms in a two-week nest life, and earthworms aren't even their main food! How can parents keep up with the demands of such a hungry brood? Hunting and feeding takes every waking hour. In the northern latitudes of Alaska, feeding time may extend to 21 hours a day. A robin makes an average of 100 feeding visits to its nest each day. With that schedule, there's no time to go far for food--another reason why a good territory is important.

Pig Out!
Baby robins sometimes consume as much as 150 percent of their body weight in a 12-hour period, which means a good territory is essential for feeding a hungry family. This makes us wonder:

Challenge Question #6:
"How many pounds of food would YOU have to eat in a 12-hour period to comprise 150 percent of your weight?"

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

How Do Robins Find Worms?
Robins spend much of their lives searching for one of their favorite foods, earthworms. Most scientists now conclude that they find these worms by vision, thanks to experiments by an ornithologist named Frank Heppner.

In his experiments, Heppner investigated all the robins' senses. To prove robins use vision, he needed to rule out the other senses robins might use to get information about worms. A list of the equipment he used is provided below. But think about this:

Challenge Question #7:
"If you had the materials Frank Heppner used, how would you design experiments to prove which sense(s) robins use to find worms? Why do you think he used each of these materials?"

  • Pieces of dead earthworm
  • Living earthworms
  • Rotten eggs
  • Decaying meat
  • Rancid butter
  • Mercaptoacetic acid (which smells like a cross between sewer gas, rotten cabbage, a skunk, and a stinkbug)
  • A small drill
  • A tape recorder that was extremely sensitive at low frequencies

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

Discussion of Challenge Question #4
Last week we said that a robin's diet during the breeding season (spring and summer in the Northern Hemisphere) was mostly earthworms and soft insects. We asked, "What are the advantages of the diet a robin eats during the breeding season?"

Hirsh and Sian at Iselin Middle School in New Jersey responded: "Sping is the breeding season. At this time they eat earthworms and insects. They need the proteins that are in the earthworms and insects so that their babies grow healthy. The protiens help their cells to properly develop."

The warmer temperatures and increasing hours of sunlight bring the whole food chain back to life. Earthworms and insects are once again abundant. Luckily, robin parents with themselves and hungry nestlings to feed do not have to search far for plenty of good food. The high-protein worms and insects help the baby birds grow quickly, too.

Discussion of Challenge Question #5
"When a robin hunting for food cocks its head, do you think it's listening or looking?"

Students from Peabody School, Washington, D. C. had the right idea. Ms. Murdock sent these answers: "Kasib thinks the robin is looking because he's got to see the worms or he'll pass by the worms. Leigh thinks that the robin is looking because usually they don't have their heads down like that."

Kristina Anderson gets a big "hooray" for sending another important part of the answer: "I think that it's looking because a robin can't move its eyes around in its sockets like we can."

We'll add just one thing: Because a robin's eyes are on the side of the head, robins must tilt the head to see objects directly in front of them.

Everyone who wonders how scientists know that robins use sight and not sound in their search for earthworms will enjoy digging into this week's Challenge Question #7!

You can use the data above to make your own maps, or print and analyze our maps.

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:
2. In the Subject Line of your message write: Challenge Question #3 (or #6 or #7).
3. In the body of each message, answer ONE of the questions above.

The Next Robin Migration Update Will be Posted on March 14, 2000

Copyright 2000 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form

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