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Signs of Spring Update: April 5, 2002

Today's Report Includes:

Redwings and Other Blackbirds Still on the Move!

Common Grackle
(Click e for some identification tips!)

Anthony Sauber of Jackson, Michigan, wrote on March 25: "We feed black oil sunflower seeds at a feeder. We observed two Red-winged Blackbirds (both males) this morning at 10:00 A.M. Along with this sighting, we observed possibly 200-250 larger blackbirds with a kind of purplish shiny head feeding on the ground well away from the feeder." Anthony's large blackbirds are grackles.

Click on the image at the right for tips to know a grackle. If crows, starlings, grackles and blackbirds have you confused, you'll find clear help here:

First Female Red-winged Blackbirds Return
Photo Courtesy of Ann Cook

Photo by Ann Cook

Now that male redwings have established their breeding territories, the first females are appearing. So far they've arrived in central and southern states, but not the north. Bradley Aukes of Wellsburg, Iowa, reported on March 21 that "During this past week they have been seen pairing off." But in the northern states and provinces, sightings so far have been males.

When they DO finally return, female redwings, like males, often return to the same territory where they nested the previous year. Why do you think the females return so much later than the males?

Challenge Question #17:
"List as many reasons as you can think of that female blackbirds return a couple of weeks later than the males."

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

Ready, Set, GO!!
Within a few days of the females' return to a marsh, they start building their nests. These nests are fairly large, and usually close to the ground or surface of the marsh, but are tricky to find. Below we've listed the steps in constructing a redwing nest--but the steps aren't in the right order. That's your challenge!

Challenge Question #18:
"In what order would a red-wing blackbird do these steps in building a nest?"

  • The female lines the inner cup with fine grasses.
  • The female weaves stringlike fibers around vertical supports such as cattails.
  • The female weaves the bottom platform to this, using coarse, wet grasses and marsh vegetation.
  • The male performs a "Symbolic Nest-site Selection Display," picking up and manipulating nesting materials in an area that the female is inspecting. Sometimes he performs the "Symbolic Nest-building Display," making nest-building movements by an existing nest from the previous year.
  • The female uses mud to build the inner cup.
  • The female builds the outer structure of the nest cup out of medium-sized, wet leaves and decayed wood.

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

A Weighty Matter
A fully-grown male redwing weighs about 2 1/2 ounces. A female weighs about 1 1/2 ounces. Redwings usually lay 2 or 3 eggs in a clutch, sometimes 4. One ornithologist tested the weight-carrying capacity of a redwing nest and discovered that the nest could support 1.8 kg. Doesn't that seem like a lot?

Challenge Question #19:
"How much weight would an average redwing nest need to hold? What are some reasons that a nest can hold so much more?"

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

Who's Been Laying Eggs in My Nest?
Like other songbirds, redwings build nests, incubate their eggs to keep them warm, and then take care of their babies. But there's one kind of bird in most of North America that leaves the responsibility of raising its babies to other bird species. Such a bird is called a brood parasite. Fewer than 1% of al birds are brood parasties. Why would brood parasitism be a good adaptation for a bird? Which of North America's birds is a brood parasite? Read all about it here:

Then come back and try this activity:

Most birds recognize their mates based on what their own parents look and sound like. What would happen if brood parasites were like that? No one knows precisely how cowbirds recognize their own species. As a class, discuss your own ideas about this mystery. Then work in pairs or small groups to draw a comic strip, write a rap or haiku, or create and peform a skit that illustrates your ideas.

Try This! Observations
If you have access to a marsh where red-winged blackbirds are nesting, try to spend 15 minutes out there every day for a couple of weeks. Find a good observation spot where you can stand or sit, and watch and listen closely to the females. Can you spot where they are building nests? (Don't get too close!) How do females interact with males? How do they interact with other females? In some areas, females defend a territory against other females. In some areas, one male will nest with more than one female. Do you see evidence of either of these in your marsh? Taking careful notes, see if you can make a simple map of your marsh with circles around the male and female redwing territories.

Blackbird Language Lessons
Did you know that female red-winged blackbirds produce their own song? You can find out what's going on in the redwing world if you know what the birds are talking about! To learn more about redwing sounds, check out our

Planes vs. Boats: Discussion of Challenge Question #15
Scientists monitor tagged whales from boats and from small planes. We asked: "Why do you think the scientists can follow the whale from 20-30 nautical miles in a plane, but only 2 miles from the boat?"

Dylan from Ferrisburgh Central School was right about the curve of the earth! Here is what he shared:
"I think you can only follow a whale 2 miles on a boat because when the whale goes underwater, it's hard to see the whale so you could eventually lose sight of it in a couple miles. Also, when you get farther and farther from the whale, since the earth is round, after two miles you're not going to see the whale."

Did you know that the tags in the right whale tracking project send out Very High Frequency (VHF) radiowaves? In fact, the tags ONLY send signals when they're on the surface because the radio waves cannot go through water at all! Because these waves travel outward from the tag in straight lines, the curvature of the earth makes a difference. From the surface of the water in a boat, the researchers can get a signal from only a short distance. (The bigger the boat and the higher the antenna, the farther away they can get -- in this case about 2 miles.) But an airplane can get an even greater line of sight -- some 20-30 miles.

Whale Populations: Discussion of Challenge Question #16
"The information in the chart shows 7 years of data of the recorded births of northern right whales. What other kinds of information would you need to have before you could get a better idea about this whale population?" (Be as specific as you can about other factors you would need to know.)

To understand population dynamics, scientists must gather a great deal of information about their species. In looking at the number of recorded births, these questions are also important:
1. At what age is a female right whale able to bear calf? (Starting between 7 and 10 years old.)
2. Do mature female right whales produce a calf every year? (Females reproduce every one to three years.)
3. Do they produce twins or triplets? (Females carry and give birth to only one calf at a time.)
4. How long do right whales live? (It is difficult to determine right whale longevity. Researchers estimate life spans at around 30 years; however, there are known cases of 65 years.)
5. How many years are they reproductively active? (The average life span is about 30 years, so about 20 years on average.)
6. What is their mortality (death) rate? (This is a difficult question to answer! Where could you find this information?)

Please Report "Signs of Spring" From Your Part of the World!
Report your "Signs of Spring" sightings to Journey North.
Remember to share your sightings of first frogs, earthworms, red-winged blackbirds, barn swallows, emerging leaves, flowing sap, melting ice and other spring events.

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-spring@learner.org
2. IMPORTANT: In the Subject Line of your message write: Challenge Question #17 (OR #18 OR #19).
3. In the body of the message, give your answer to the question above.

The Next Signs of Spring Update Will be Posted on April 12, 2002.

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