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American Robin Migration Update: April 17, 2001

Today's Report Includes:

This Week's Migration Maps and Data

(For data, click on caption.)

First Robins
Seen

Waves
of Robins

First Robins Heard Singing


By mid-April as robins are found singing in more and more places, you'd think keeping track of their migration would start to get mundane, but robin migration is always fascinating. With the cold spring, waves of migrants are still crowding into some snowy areas even as a few intrepid individuals reach the Northern Observation Posts. One observer reports 65 robins seen in a bird loop around Manchester, VT, on April 11, despite a large amount of snow. And that same day, teacher Dave Kust counted 50 or more robins in 3 backyard trees in Minneapolis, MN, at about 7:30 PM. He writes,

"There were another dozen splashing in the water near the edge of the pond. Is this another wave passing through or are they all gonna stick around to nest, I wonder? Plenty of worms around from the good soaking rains we've been having."

Journey North's robin expert says that 50 robins in a small area is way too many for nesting. They would spend all their time fighting, trying to keep one another off their territories. This group is a migratory flock, but there may well be two or three pairs in the same yards that will be nesting after the rest disperse. As a matter of fact, sometimes robins ARE nesting even as migratory flocks are still passing through. They're already nesting in La Crescent, Minnesota, according to this April 14 report:

"Here in La Crescent , there is a robin sitting her nest which is built on my neighbor's drainpipe, under an eave. Great place. It starting building a few weeks ago, was disturbed when she pulled down some Clematis vines near the pipe, but is now back and definitely incubating." (Drg5934@aol.com)


News From Northern Observation Posts
Robins have arrived at most of our northern posts, but our observers in Soldotna, AK are still patiently awaiting their first. In Haines, AK, Pam Randles had a lucky Friday the 13th, reporting that robins broke into song that day. "All of a sudden, they were singing everywhere. The lovely sound of spring." Ken Moore had a smaller wave on April 14 in Stirling, AB. He writes, "Call it a wave of robins if you like. Three robins together. No songs being sung but the robins' characteristic sound which defines they're alive, well and about to resume their territorial stronghold is starting to be heard here in the mornings."

Many more robins are still on their way north. Journey North's writer Laura Erickson had over a hundred hunkering down in the trees of her Duluth, MN, yard on April 16--as snow swirled through the "spring" air.

Come and Get'Em
Meanwhile, the robins back on territory are happily hunting worms. Imagine eating a slurpy, muddy worm. Robins don't just imagine this, they DO it, dozens of times every day in spring and summer. Robins eat a host of other small creatures, from spiders to snakes, but are especially well-adapted for eating worms. According to your sightings, earthworms are up and ready for the robins!

Now that the worms and robins are back, we've got worm facts and fun in this week's report. Read on!

Listening or Looking?

"There were 3 robins in my yard, all doing their little tippy-toe run, head cock, get bug/worm dance," wrote Cathy from North Augusta, SC, way back on February 25. (catag57@hotmail.com)

An observer in Brighton, NY said:

"Two robins were poking around at the edge of the road, maybe looking for worms, or smelling for them, or listening for movement inside the ground." (hrock5@cs.com)

Looking, smelling, running, listening. Robins spend much of their lives searching for one of their favorite foods, earthworms. How DO they find them? An ornithologist named Frank Heppner wanted to know, so he set up some experiments. Dr. Heppner needed to investigate all the robins' senses. A list of the equipment he used is provided below. Like these observers, everyone who wonders which senses robins use in their search for earthworms will enjoy digging into this week's first Challenge Question. Think about this:

Challenge Question #18:
"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.)

The Spread of Worms. . .and Robins
Were earthworms always here? Yes and no. During the time that glaciers covered much of North America, earthworms disappeared from the frozen soil. It would have taken centuries or longer for earthworms to become re-established on their own, but human actions speeded up the process. Farmers and gardeners brought potted plants from other places for planting, inadvertently releasing earthworms that were in that soil. And when farmers tilled the soil to make it easier for tiny roots to grow, they also made it easier for the worms to tunnel through the soil. As worms increased, so did robins. In 1932, a scientist named Frank Farley found that robins had increased 100 percent in Alberta in the 50 years since the 1880s.

Robins aren't only increasing northward. They've also started breeding in places farther south than was ever known before people changed the land. For example, when America was first settled by Europeans, robins were rare. They were local breeders in Texas except in the eastern, forested section of the state. The ground was hard and dry, very little mud was available for nesting, and few trees were available for building nests in. Beginning around the 1920s, robins increased as people planted trees and started sprinkling lawns. Robins began breeding in Oklahoma after people planted orchards, and in dry parts of California after people started building farms and growing shade trees. Has the presence or activity of robins changed in YOUR area? If so, what might be some reasons?

Breakfast, Lunch, Dinner
In spring and summer, robins get 90 percent of their diets from worms and other small animals. But they concentrate on worms mainly in early morning and late afternoon. At mid-day they switch to eating fruits and hunting in trees for spiders and other small creatures.

Challenge Question #19:
"What might be the reason for a robin's feeding pattern of hunting for worms in early morning and late afternoon, and eating fruits, spiders and other small creatures at mid-day?"

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

Pig Out!
Baby robins sometimes consume as much as 150 percent of their body weight in a 12-hour period. Each young robin may eat 14 feet of earthworms in a two-week nest life, and earthworms aren't even their main food! This means a good territory is essential for robin parents to feed a hungry family!

Challenge Question #20:
"How many pounds of food would YOU have to each in a 12-hour period to equal 150 percent of your body weight?"

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

Worms, Worms, Worms!

A Humorous Read-Aloud

Robins eat worms, and plenty of them. The little worm in Gary Larson's book, THERE'S A HAIR IN MY DIRT: A WORM'S STORY, isn't happy with his lot at the bottom of the food chain. In an outburst at the worm family's table one day, the little worm yells, "Dirt for breakfast, dirt for lunch, and dirt for dinner! Dirt, dirt, dirt! And look--now there's even a hair in my dirt!"
Yes, earthworms get their nutrition from many forms of organic matter in soil. They eat decaying roots and leaves, and tiny organisms such as nematodes, protozoans, rotifers, bacteria, and fungi. Worms also feed on the decomposing remains of other animals. An earthworm can consume up to one-third of its own body weight in just one day!
No wonder worms are such a nutritious food source for robins. Even if a robin won't care how many calories are in a worm, WE still wondered. We asked Forest Ecologist Cindy Hale if she knew the answer. You can find her reply here:


Teacher Tip: Observing Worms
Fall and spring are a wormís favorite seasons. Dark, cool, and moist: Thatís how worms like it. How about a worm hunt? This Journey North activity tells how to bring up worms and what to observe after you've collected some. Students can work in teams with one partner as recorder, or draw and record in their own journals. You'll be surprised at the discoveries in these wormy workings!


Tug of War!
Whether robins hunt worms by sight or sound is only part of the question. Have you ever watched a robin pulling a worm out of the ground? Do some research on earthworm anatomy to answer:

Challenge Question #21:
"Why must a robin tug so hard to get a worm out of the ground?"

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

Teacher Tip: Mapping Territories
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 here:

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. 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.

Teacher Tip: Nest-building Blueprints
Imagine you are a robin. What makes a suitable building site for your nest? What materials will you use? How do you build a nest when you don't have hands? Why do you, the parents, sleep on a nearby branch after the first week, except when it rains? Why do you move out and build a new nest after the babies leave? You'll get help with these answers along with step-by-step instructions for building a robin's nest with this terrific Journey North lesson:

Whassup With That Robin?
We heard from several concerned readers about robins crashing into their windowpanes, and The Kashdan Family in Vienna, VA wonders what their robin is up to. They asked Journey North: "A robin that hangs around our deck keeps trying to crash through the French doors leading out to the deck. Sometimes he hangs out at a nearby tree and tries to come into the kitchen window. There is a small birdhouse on the deck where small birds like to nest, and sometimes the robin tries (unsuccessfully) to squeeze in. Any thoughts on this behavior, and what can we do for this poor bird?"

Our robin expert, Laura Erickson, has the answer. "Your robin is probably NOT trying to use the nest box, but rather attempting to take some of the nesting materials our of it to use in its own nest. Robins simply don't use cavities or nest boxes. A much more likely site for a robin's nest is a window well, a support under an eave, or a spruce tree branch.

"The reason it's bonking into your window and doors is that the robin (usually male but sometimes female) sees its reflection in the glass and wants to drive away a potential competitor for its territory. It's a colossal waste of energy, but in the natural world robins never had to deal with clear glass until the past century, and they haven't evolved techniques for recognizing it or realizing that the reflection is just an image of a bird."

Julie's Buddy Bulletin and Robin Hood Roundup
Julie is a Journey North writer who looks for her robin, whom she calls Buddy, to come back each spring. She reports, "No sign of Buddy yet!" But when Julie went to her kitchen window on April 9, she said, "Robin Hood flew down of the tree above and kindly requested his mealworms! It will be his second year with us. He watches us a lot, especially when the weather is bad. And he's really watching for hawks now. He did the "peek" and "tut" alarm yesterday--and sure enough, there was a hawk!"
Julie is still hoping for Buddy, but hasn't seen him yet. If you missed her story about Buddy and Robin Hood last time, here it is:

Early Bird Contest: Results for Challenge Question #13
The robins are back in Anchorage, and we think we've got the answer: "When do you think the first robin will be spotted in Anchorage, Alaska (61.22 N, 149.90 W)?" So who won this year's Early Bird Contest?

Did Sand Lake Elementary teacher Mike Sterling see the first robin? He's the first one to report a confirmed sighting to Journey North: "A big, bull robin arrived April 8 in the tree outside my bedroom window, warbling his territorial challenge to all the other robins that weren't there yet. He's early, he's big, and he's got the prime turf."

That means our Early Bird Contest winners are the fifth graders in Pat Gaines' class! They said,"We thought long and hard about when the robins would be seen in Alaska, but could not agree on any one date. We chose dates--earliest being April 15 and the latest May 30. I certainly hope that they have their robins return sooner than any of our guesses." Congratulations!

I certainly hope that they have their robins return sooner than any of our guesses. Pat Gaines' 5th grade. Congratulations!

Nesting? Not Yet! Discussion of Challenge Question #16
"What things can you list that a pair of robins needs in their territory before they can start nesting? List as many things as you can."

Students from T.R. LEGER SCHOOL in Carleton Place, Ontario, wrote:

"Dear Fellow Robin Scientists, we think robins use grass, mud, small branches, hay, leaves and feathers."

The fifth graders from Tom Longboat P.S. in Scarborough, Ontario, and Mrs. Nunally's second grade class at Peter Woodbury School in Bedford, NH added several more things to the list.

Their answers included:

    • water, not frozen (Robins have to find mud.)
    • their own territory
    • a tall tree with a thick, strong branch in a place that is safe from predators
    • leaves on the tree for shade, to keep the nest dry, and for camouflage
    • a secure spot to build the nest so it won't get loose and fall
    • bare (thawed) ground with no snow so the robins can find worms

Thanks to all of you for your answers! Laura Erickson also reminds us that a nest location protected from the sun can be under a hanging eave, in a conifer tree, or in a tree that has leafed out. (Robins usually wait until leaves are out to start nesting, or build their first nest in a conifer.) Also, there shouldnít be too many more frosts at night, because freezing and thawing mud nests can cause them to get crumbly.

Let's Vote: Response to Challenge Question #17
Last time we asked for your opinion: "Do you think communities should pass laws requiring people to keep housecats inside as a measure to protect songbirds? Vote yes or no." These two comments sum up your votes:
Mrs. Nunnally's second grade class at Peter Woodbury School in Bedford, NH agrees that cats should not be allowed to roam all over outside. (NUNNALLYR@sau25.net)
Sigrid Benson, Gulf Breeze, FL wrote, "Domestic cats are NOT native to this hemisphere. They originated in North Africa. The wildlife here was not evolved to cope with this unnatural predator. Cats' predation has also cut down the populations of natural predators. My cat is an INDOOR cat." (Dirgis3@aol.com)

Remember to send your entries to the poster contest!

Note To Teachers: We'd Appreciate Your Thoughts!
In our May 1st update, we'll be asking for your feedback on the Journey North program. Watch for our Year-End Evaluation Form and please plan to take the time to send your suggestions and comments. The information you provide at the end of each year is the single most important tool used to guide our planning.

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-robin@learner.org
2. In the Subject Line of your message write: Challenge Question #18 (or #19 or #20 or #21).
3. In the body of each message, answer ONE of the questions above.

Please Report the First Robin you SEE, the first robin you HEAR singing, and other interesting robin observations. Your reports will be incorporated into these Robin Migration Updates.

The Next Robin Migration Update Will be Posted on May 1, 2001.

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

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