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Whooping Crane Migration Update: April 3, 2001

Today's Report Includes:


Tom Stehn Reports: Good to Go!

Migration Route
Map by Claudia Fonkert
Macalester College

Dear Journey North,
When I did my last count on March 29, just about all the whooping cranes were still here. However, it's time for the whooping cranes to start their migration. In past years, the majority of departures take place April 4-12. The birds don't leave in one big flock, but instead leave in small groups.

A pair may go, and sometimes a neighboring pair will actually take off right behind them and all migrate together. But I've also observed one pair leaving and 30 minutes later some other cranes from the same area depart. Usually several small groups of cranes may all leave the same day, but not be flying together. I've always felt that one pair's departure may actually influence other birds to start the migration. Kind of "peer pressure" behavior.

Tom Stehn, Whooping Crane Coordinator
U.S. Fish and Wildlife Service
Aransas NWR

Read Tom's full letter to see why he predicts an on-time departure, perhaps starting today! Find out where the Aransas blue crab population stands and the possible consequences for this year's nesting season.
Please read Tom's complete letter here:

Lone Crane
Remember the single confirmed whooper sighting from last week's report? It was quite likely the whooper that wintered in West Texas with sandhill cranes. Did you wonder what the whooper was doing with sandhill cranes? Bird expert Laura Erickson speculated: "It may be one of the whooping cranes that was raised by sandhill cranes in an early reintroduction plan. These cranes imprinted on sandhills and flocked with them because that's what their parents looked like. But all cranes are basically social birds, and generally feel most comfortable with other cranes. If a whooping crane is separated from its mate or (more likely) is an immature and its parents lit out ahead of it, it often joins with other cranes, even of another species, because of that need for a flock. One spring day when I was birding by some sewage ponds in Wisconsin, a lone sandhill crane flew by. When I made an imitation of its call, it changed course and flew directly toward me, and circled over my head three or four times, looking at me with what SEEMED like wistfulness. I imagined it was wishing it had a flock of its own kind and was almost willing to settle for me."

Try This! Flock or Solo
Sometimes flocking in birds is important for their well being. Sometimes it's better for birds to be separate rather than in flocks. Can you list some advantages and disadvantages of flocking, and some advantages and disadvantages of being separate from a flock?

Timing is Everything
Last time Tom Stehn told us: "Not only do birds have an excellent compass and GPS system in their head that allows them to travel across North America; they also have a very accurate internal clock. As the days become longer in the spring, the cranes somehow can sense the longer days and know when it is time to leave for the north. If they leave too early, they will encounter frozen conditions and find less to eat during the migration. If they leave too late, they won't have enough time to raise their young before fall blizzards arrive."

An animal's very survival depends on being in the right place at the right time. To tell time, animals use "clocks" inside them that measure the daylight. Internal or biological clocks are found in all living things, including humans. They signal when to wake, when to sleep, when to forage, when to fly. These master clocks are set according to the world's most reliable timekeeper--the sun. Animals detect sunlight changes during the seasons and set their internal clocks. The changing photoperiod, or amount of daylight hours between sunrise and sunset, governs the annual rhythms of life throughout nature. Do you have pets who seem to be able to tell time? Do you wake up automatically every day about the same time? Let's test how well your body can tell time!

Teacher Tip: Test Your Biological Clock
  1. Cover all the clocks in the classroom. At ten random intervals during the day, ask students to guess and record the time--and the clues that help them judge. Some external clues might be school bells, smells from the lunchroom, or noise in the hallway.)
  2. At the end of the day, discuss results.

A Second Flock on the Horizon!
As we track the Aransas-Wood Buffalo whooping cranes on their spring migration, exciting plans are underway (pending government approval) to establish a second migratory flock of 10 to 25 wild whooping cranes. With whooper numbers down this year, experts are happy to say that an escorted migration for whoopers looks like a real possibility for 2001. This new flock will migrate between Wisconsin and Florida.

The plans are based on what experts learned during the Operation Migration project in the fall of 2000. This escorted sandhill migration was a trial to see if the same plan might work with endangered whooping cranes. You may have seen the 1996 movie "Fly Away Home," where geese learned their migration route by following an ultralight airplane instead of their parents. Since then, sandhill cranes have been helping scientists develop successful rearing and migration techniques to use with endangered whooping cranes. On October 3, 2000, 12 sandhill cranes followed an ultralight plane in Operation Migration, an exciting migration experiment co-founded by Bill Lishman and Joe Duff. This migration ended successfully when two ultralights landed at the St. Martins Marsh Aquatic Refuge in Florida with 11 cranes on the 11th day of the 11th month of the year 2000. As soon as government approval is gained, crane experts will use the information gathered to show the same migratory route to the world's first reintroduced flock of migratory whooping cranes.

The Chosen Chicks

Courtesy Operation Migration

The whooper chicks for the project are to be transported from the U.S. Geological Survey's Patuxent Wildlife Research Center in Maryland to the Necedah National Wildlife Refuge in Wisconsin in late June. The chicks will undergo about 30 hours of training with the ultralight planes before their long migratory flight. In early October, they are to start winging toward Chassahowitzka National Wildlife Refuge in central Florida, following the ultralights and pausing at more than 30 secret rest areas along the way. Biologists believe that by the spring of 2002, the cranes' instincts will prompt them to return to Wisconsin all on their own. Over the next decade, the Fish and Wildlife Service hopes to establish 25 nesting pairs of whooping cranes that will learn to make the migration without guides. This is the way it was a century ago, until the last of the wild Wisconsin/Florida flock succumbed to hunters and a loss of nesting areas, which were taken over for agriculture. The last recorded migratory flock was in 1911. The suspense is mounting and the hope is great. Maybe next year, you will be following the journey north of not one, but TWO migratory flocks of wild whooping cranes!

Interested students can read highlights from the Sandhill Crane Operation Migration Journal here:

To learn more about the reintroduction of the new migratory flock of whooping cranes, see:

Where are the Missing Sandhill Cranes?
Will the history-making cranes from Operation Migration fly away back home to Wisconsin, all on their own? Last time we told you they were missing but the USFS expected them to turn up soon. Where are the cranes? We know that whooping cranes can fly at 35-45 mph. Our flock departed from Chassahowitzka National Wildlife Refuge in central Florida (Crystal River, FL at 28.9 N, 82.59 W) on February 25. We hope they were headed toward the Necedah National Wildlife Refuge (44.02 N, 90.07 W) in Wisconsin. Sharpen your pencils and figure out the answers to:

Challenge Question #10
"If they flew 6 hours a day, approximately what date would the sandhill cranes arrive at Necedah National Wildlife Refuge near Tomah, Wisconsin? What are some natural causes that might keep them from migrating for a day or two? Where do YOU think they are right now (Give the date of your guess)?"

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

Are you keeping your eyes on the skies? Anyone who is fairly certain that they have seen these birds is asked to share the information with the crane tracker by leaving a message at 352-564-8321 or 612-804-0959. Here's what to watch for:

All of the birds have leg bands with a red-over-green banded radio transmitter on the right leg and various colored bands on the left leg. It is possible they will be traveling as a group rather than single birds. Do not approach any cranes up close. It would be better NOT to identify the birds than to have them become tamed through contact with people. These migration study sandhill cranes need to stay wild!

Poor Nesting Season? Discussion of Challenge Question #7
Last time asked: "Why does Tom Stehn predict another poor nesting season ahead?" The answer was found in Tom's full report, where he said:

"With the scarcity of blue crabs this year due to the summer drought hurting blue crab reproduction, I believe the cranes have actually lost energy throughout parts of this winter. I don't think they have consumed enough energy and built up enough fat reserves to have a very successful nesting season this spring. Some of the pairs may not even attempt to nest if they are not in good enough condition."

Tales Told by Crane Voices: Answers for Challenge Question #8
Last time we asked you to fill in the blanks after reading Dr. Bernhard Wessling's analysis from winter voice recordings at Aransas:
  1. Twenty-one whooping crane pairs have been found back again and matched with their calls from Winter 99/00.
  2. Four whooper pairs (20%) have significantly shifted their territory.
  3. Two pairs have new mates.

A Closer Look: Discussion of Challenge Question #9
Last time we asked: "How would you explain the reasons why herons fly differently from cranes?"

Whooping Cranes in flight.

Great Blue Heron in flight. Courtesy of Brian E. Small.

Cranes have relatively light heads and necks, and can fly the normal way with neck outstretched. Because herons have heavy bills and heavy, powerful neck muscles for striking fish, too much weight is forward of their wings. To fly, herons must have as much weight as possible near their center of gravity, so they pull their necks in.

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-crane@learner.org
2. In the Subject Line of your message write: Challenge Question #10.
3. In the body of EACH message, give your answer to ONE of the questions above.

The Next Crane Migration Update Will Be Posted on April 10, 2001.

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

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