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American Robin Migration Update: April 18, 2000

Today's Report Includes:

Today's Migration Maps and Data
The first robins have reached southeast Alaska! On April 1, Ms. Randles of Haines High School reported the first robin in Haines, AK. In Petersburg, AK, the first robin was spotted on April 4 by Caroline Engebretsen, and on April 16 a wave of robins was reported in Juneau. Jim Galea wrote, "I have sighted 2-3 robins in my yard in the past 3 days."

FIRST Robins and WAVES of Robins

Dates Robins First HEARD Singing

Today's Data:

Meanwhile, you're probably wondering. . .

Have Robins Reached Anchorage YET?
Hot off the press is this report from Sand Lake teacher Mike Sterling in Anchorage:

"No robins. Good news though--the signs of spring are accumulating. For one, we've been slapping these big mosquitoes that manage to survive the winter in leaf litter and stuff. For another, the mercury did not dip below freezing last night. I'm riding my bike to school every day, so I'd hear robins along the way if they were there. I'm outside every spare minute, too--my kids won't let me rest when I pull in the driveway. My students are all on alert. Some of them are actually writing reports about WHY robins migrate. But they haven't seen any, either. A warm, sunny weekend closed out by increasing clouds and a strong wind provided perfect thawing conditions. They'll be here SOOOOOOON!"

So, tune in NEXT time to find out (we hope!) who won the Early Bird Contest by predicting this year's arrival date of robins in Anchorage.

Robins Finally Find Frisco
Among the sightings of first robins came a surprising one from Frisco, Colorado on April 8th. John Kejr wrote:

"Saturday our first robins appeared and they were singing. Last week much of our snow melted and we saw bare ground in many places for the first time in months. Ususally, the first robins show up just about the time that we start seeing bare ground. This year is no exception." Find Frisco, CO on a map (39.57 N, -105.96 W) for a clue to the answer for:

Challenge Question #16
"Why do you think it took robins so long to reach Frisco, CO when robins have been at the same latitude in other areas for many weeks?" (Clue: Find Frisco, CO on a map.)

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

Go Lay An Egg
While we're waiting for robins to reach the end of the migration trail, the breeding cycle is underway in places where robins have already arrived. Courtship, nest building, egg laying, incubation, and care of the young all take place so robins can make more robins. Or, as scientists would say, "pass their genes on to the next generation." What's the story behind those little blue eggs?

For starters, a robin egg must be incubated for 12-14 days to develop normally. Except for about a 10-minute break per hour during daylight hours, the female robin sits on the eggs all day long. Just like a recipe for baking a cake, a robin egg must be warmed for a specific length of time and must also be kept at a specific temperature. So sharpen your pencil and tell us your answer for:

Challenge Question #17
"If you add up all of the time a robin egg is incubated, how many hours do you estimate that it takes for a robin egg to develop properly?" (Assume the egg is incubated for 13 days and that there are 15 daylight hours. Don't forget to subtract the time a mother robin takes for "breaks"!)

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

Eggstra! Eggstra!
Working on this CQ might make you wonder some other things about laying eggs and raising robin babies. Who do you think does more work in raising young, the robin male or the female? Which robin takes more risks, the male or the female? Which robin would you rather be: a male or female? Why? You'll be able to answer these questions a lot better after digging into the pages we've made to help you collect clues and sort facts:

Try this! Serve Some Eggshells to the Birds
Your leftover breakfast eggshells are good for birds! They can provide calcium birds needs in the production of new eggs. So pluck those eggshells out of the trash, rinse them, and save enough to fill a cake pan or pie tin. Then prepare the eggshells and help the birds:

How Do You Like Your Eggs?
  1. Place the pie tin of clean eggshells in a 200-degree F. oven for 20 minutes. (The heat destroys any salmonella bacteria that could make birds sick.)

  2. Cool and finely crush the eggshells.

  3. Serve them to the birds! Put crushed eggshells in a try or fly-through feeder, or scatter them on the round. You can also put the eggshells in a suet cake. The recipe below is just one way to make a suet cake.

Suet Cake

  • 1 pound of lard
  • 2 cups creamy peanut butter
  • 2 pounds of coarsely ground suet from the meat department of the supermarket
  • 1 cup prepared eggshells (cleaned, baked, and crushed as above)
  • 7 cups of "food" (any combination of leftover bread crumbs, cereal, oatmeal, sunflower chips, cornmeal, raisins, or flour)

Melt the lard. Take if off the heat and add the peanut butter and ground suet. Add crushed eggshells. Then mix in the remaining "food" ingredients. (It will be difficult to stir.) Divide and pack your suet cake mixture into containers, such as the individual milk cartons from school. Hang on tree branches for the birds, who love to eat suet cake all year round. You can also put some suet cakes into the freezer to save for later.

Thanks, Rachel Carson!
April 22 marks the 30th anniversary of the first Earth Day. Nearly all across the continent, robins are singing today. But if it weren't for Rachel Carson--and her courage--the songs of spring wouldn't be what they are today.

Rachel Carson wrote a landmark book called "Silent Spring." In it she told the world about the dangers of chemical pesticides. She warned that many pesticides were poisonous and had spread throughout the environment. Even the backyard robin was threatened. One example: Beginning in the spring of 1955, as each wave of migrating robins appeared on the Michigan State Campus, they would die within a week. People first suspected a disease. But after several years they concluded that, "in spite of the assurances of the insecticide people that their sprays were harmless to birds, the robins were really dying of insecticidal poisoning."

This full story is told in Silent Spring. Find a copy of this book and then see if you can answer this question:

Challenge Question #18
"If people weren't spraying robins directly with pesticides, exactly how did these chemicals kill the robins?" (Please describe the process, step-by-step, in as much detail as you can.)

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

Remember: When you hear a robin singing in your backyard today, you have Rachel Carson to thank!

Numerous Nests: Response to Challenge Question #12
Last week we asked: "Banding studies show that some robins can live up to 12 years. How many nests might a 12-year-old robin build over its lifetime?"

Mrs. Boyle's 4/5 Multi-age Robin group found the information while reading Journey North's web page on how to make a robin's nest, and many of you reasoned by doing the math. Thanks to all the students below who sent answers, which ranged from 20 up to 36 nests over a lifetime.
  • Nathan Matsunaga, St. John the Baptist School in Milwaukie, Oregon (ekennedy@stjohnmilwaukie.org)
  • John Smyth, Timothy Reilly and Hirsh Choksi from Iselin Middle School 7A (iselin5@injersey.infi.net)
  • So myung Choi. (smchoi@jat.co.kr)
  • Kristen Basiaga, Griswold Middle School in Rocky Hill, CT (Seishigirl13@cs.com)
  • Katie Vernali (KitKat2V@aol.com)
  • Erica Marie, Kelley Anne, Katie K., Allisa G., and Linda B. from Mrs. Boyle's 4/5 Multi-age Robin group (pboyle@ogdensburg.neric.org)

Made in the Shade: Response to Challenge Question #13
"Give at least two reasons why a robin's first nest of the season is usually in an evergreen tree while the second and third are more often in a leafy tree."

Kristen Basiaga from Griswold Middle School in Rocky Hill, CT had the right ide when she said that "a robin may be afraid to build nests in more open areas." In many areas, robins start building nests when leaf out hasn't occurred. Evergreen trees provide protection from predators, who would have an easier time discovering the nest without the protection of leaves.

Also, the eggs and nestlings would be more vulnerable to weather without the dense protection evergreens provide before leaf out of other trees. Rain, late snow, and wind would be a bigger problem, and so would sun. Before their feathers grow in, baby birds are VERY vulnerable to sunburn--and sunscreen isn't an option! By the time the young from the first nest have fledged, the leaves have come out on deciduous trees and robins can make their second nests there in safety.

Family Album: Discussion of Challenge Question #14
"How many offspring can a pair of adult robins potentially produce if they survive a 10-year lifetime?"

We got answers from 20 to 110. Your calculations were based on 20 or 3 nests a year, with 4 babies per nest. But these same two adult robins are responsible for the hatching of grandchildren, great grandchilden, and more! In his book The American Robin, Roland Wauer cites L.A. Eiserer, who points out that if there were no mortality, a pair of robins has the potential to produce 19.5 million descendants by the end of a ten-year life span. Surprised? At the end of a mere 30 years, the original pair of robins would have 1.2 billion trillion descendants. Robins, like all birds, experience a high death rate, so this number is purely theoretical. Wow!

That's The Limit! Response to Challenge Question #15
"Why don't robins go even further north? What factors influence the northern limits of their nesting range?"

Kristen Basiaga of Griswold Middle School writes: "I think that the robins don't go any further north because they don't want to travel further south in the spring. Also, it never reaches above freezing in the arctic circle. There would be no trees to rest in. Not to mention that they would probably die of starvation (because they have little wildlife in the tundra). To top that off, they would have to fly from island to island very quickly over large bodies of water to escape the coming cold in the end of summer." (Seishigirl13@cs.com)

Iselin Middle School Grade 7A students Kostas Diotis, Anthony Meluso, Kristy Byoris, and Jessica Carpluk said: "We believe that robins don't go any further north, because they will end near the North Pole. The factors that influence the northern limits of their nesting range is freezing cold weather and the ground is frozen all the time. They would not be able to find food. (iselin5@injersey.infi.net)

Good thinking, all of you! Robins are hardy enough to breed wherever they can find what they need, which is food and nesting sites. Permanently frozen ground not only means no worms, but few if any plants, berries, insects, or trees for nesting.

Folks in Point Hope, Alaska, a village at the tip of a peninsula on the Chukchi Sea, have never seen robins in their area. Even Kodiak Island has been waiting for 10,000 years for robins to fly the mere 15 extra miles from the mainland across Shelikof Strait to their island. Robin habitat on this island was probably eliminated by ice and snow in the last glacial period. The island has far fewer plant and animal species on it than the nearby mainland. It's rare, but islanders sometimes hear a singing male. Hopeful folks say all it will take is for one female to find that male, and then Kodiak Island may have robins, too.

How to Respond to Today's Challenge Questions:
Please 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 #16 (or #17, #18).
3. In the body of EACH message, give your answer to ONE of the questions above.

The Next Robin Migration Update Will be Posted on May 2, 2000.

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