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Whooping Crane Migration Update: March 19, 1998
Today's Update Includes:
- Migration News from the Texas Coast: The Cranes Begin an Early Migration
- Ultralight Whoopers Also Migrate--Alone for First Time
- Discussion of Challenge Question #1
- Challenge Questions #4
- Discussion of Challenge Question #2
- Challenge Questions #5
- Discussion of Challenge Question #3
Migration News from the Texas Coast: The Cranes Begin Early Migration
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Tom Stehn |
From: Tom Stehn
Aransas National Wildlife Refuge
Austwell, Texas
Dear Journey North,
The Whooping Crane migration has STARTED. I did an aerial census flight on March 12 and estimated possibly a dozen
cranes had departed Aransas. The weather was gray and overcast throughout the flight which made the visibility
for finding cranes difficult. Thus, I don't know if I was simply "overlooking" whoopers, or whether
they have actually migrated. I'll know more when I repeat the census flight March 18. However, I located 95 of
the 100 adult territorial whoopers, indicating to me that most of the cranes are still here.
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Migration Route |
Ultralight Whoopers Also Migrate--Alone for First Time
Two other VERY UNIQUE whooping cranes started the migration March 5. They did a 20-mile "test" flight the day before they started for real. These are the two whoopers that were led south by researcher Kent Clegg behind an ultralight airplane between Idaho and New Mexico last fall. They are the two survivors from the 4 ultralight whoopers that made the trip south. The other two whoopers were killed by predators as they tried to adjust from captivity to becoming adapted to life in the wild.
Wonderful pictures of the cranes' migration last fall are available on the WWW:
One of the ultralight whoopers that survived the winter was the crane that had been attacked and knocked down
by a golden eagle during the fall migration. The ground tracking crew had captured the bird and rushed it to a
vet to get its leg sewn up and get antibiotics. This bird had to be hauled in a truck to New Mexico since it was
too weak to fly after the eagle attack. The two ultralight whoopers apparently followed sandhill cranes north
and are presently in the San Luis Valley in Colorado. Cranes "stage" in the San Luis Valley, spending
considerable time there waiting for the last of the winter to be over. We are anxious to see if the ultralight
whoopers return to where they were raised in southeast Idaho. They can't get away from crane researchers since
transmitters on their legs are tracked by satellite.
It is quite an accomplishment by pilot/biologist Kent Clegg to have his ultralight whoopers migrating north. He
first had to prove that he could teach whooping cranes to follow the ultralight and lead them 800 miles last fall.
Then he had to get them used to living in the wild and mixing with wild cranes at the Bosque del Apache National
Wildlife Refuge in New Mexico. Then he had to see if the ultralight birds would "know" to head back
north in the spring.
So far, Kent Clegg is batting 3 for 3 and will literally have hit a home run if his ultralight birds return to
his ranch in Idaho where they were raised. It makes one wonder where the migratory urge comes from in cranes,
but we are hoping that if cranes are taught the migration in the fall and shown a place to winter, they will migrate
back north on their own in the spring without having to be led a second time by the ultralight. This is one incredible
accomplishment and helping us learn how to teach a crane to migrate.
Cheers,
Tom Stehn
Whooping Crane Biologist
Aransas National Wildlife Refuge
Austwell, Texas
Discussion of Challenge Question #1
In our last report Tom Stehn said that, despite the very mild winter due to El Nino, the whooping cranes know not to leave too early--or they will find nothing but ice and snow when they return to their nesting grounds in Canada. Challenge Question #1 asked, "If it's not the weather that signals spring for whooping cranes, how do you think they know when to migrate?"
Anna and Daniel of Iselin Middle School in New Jersey know how the cranes know: "If the whooping cranes do not rely on the weather for their migration then they must know by the sun. As the photoperiod elongates and lessens, telling them it is winter or summer, their internal clocks are stimulated and the cranes move. We also thought that the crane's clocks might be started by the end of the breeding season and the maturing of their young."
As these students point out, animals use internal timing mechanisms known as biological clocks to "tell time," One of the most important skills of any migratory animal is its ability to tell time. As you will see during the migrations this spring, there are countless cases where an animal's very survival depends on being at the right place at the right time.
People enjoy discovering examples of their own biological clocks. These clocks control sleep and energy cycles in interesting ways. In the lesson below, explore the concept of time and your own ability to keep time. Then consider the importance of biological clocks to migratory species.
Challenge Question #4
"What if an animal lost track of time?" Choose one Journey North migratory animal. Write a story about the consequences that would result if this animal were to lose track of time. Consider all the activities the animal must do according to daily and annual time cycles. Then send us your story!
(To respond to this question, please follow the instructions at the end of this report.)
Discussion of Challenge Question # 2
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Challenge Question #2 asked, "Why do you think the people who raised the cranes in captivity dressed entirely
in white, with their bodies and faces covered?"(See photo on WWW.)
No one knew the answer to this question, so we'll ask it again with a related question:
Challenge Question #5
"What is meant by 'imprinting'" and now, "Why do you think the people who raised the cranes in captivity dressed entirely in white, with their bodies and faces covered?"
(To respond to this question, please follow the instructions at the end of this report.)
Discussion of Challenge Question #3
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Why was it so important for biologists to take eggs from whooper nests and establish a second flock, asked Challenge
Question #3? Seventh grade student Hope Buickerood of New Jersey did a beautiful job summarizing the risks of
"keeping all your eggs in one basket".
"I suppose that biologists felt it was important to establish additional flocks of whooping cranes because
they did not want the one flock of 22 cranes to die. This would mean the species would become extinct. There are
many concerns that the biologists could have about leaving the one flock on their own. For instance, the whooping
cranes might not be able to complete their migration due to bad weather. The cranes might experience breeding problems
and not increase their numbers. Some cranes might not find sufficient food or might be hunted to extinction. There
may also be
environmental concerns." (susamel@juno.com)
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-crane@learner.org
2. In the Subject Line of your message write: Challenge Question # 4 (or #5)
3. In the body of EACH message, answer ONE of today's questions.
The Next Whooping Crane Migration Update Will be Posted on April 2, 1998.
Copyright 1998 Journey North. All Rights Reserved.