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Whooping Crane Migration Update: April 2, 2002

Today's Report Includes:

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Photo WCEP, Al Perry

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Tom Stehn and Survey Plane

Four More Pairs Take Off! Tom Stehn's Field Report
"The whooping crane migration is underway, but only by a little bit, writes Tom Stehn from the wintering grounds at Aransas. "On March 28, after eight hours in the census airplane swooping, diving, circling, turning, and doing everything but breakdancing, (and every once and a while flying in a straight line), I concluded that a total of nine whooping cranes have started the migration. One of the nine has been sitting on the Platte River in Nebraska since March 20th. (Biologist Wally Jobman confirms that bird is still there, but he reported no new confirmed sightings during the past week. What do you suppose the bird is waiting for?) "The other eight are cranes in four adult pairs that are headed north to nest. These pairs probably headed north on March 24th when it was incredibly windy on the Texas coast." Windy? Tom tells you HOW windy in the next section of this Update.

"Why have 9 cranes started the migration and the remaining 185 in the flock are still here eating blue crabs and getting ready for the trip? The timing of the migration is always spread out, starting in late March and going all the way through April and sometimes even into early May before the last whooping crane departs. With the flock migrating at different times in small groups of usually 1-5 cranes, no single natural hazard will devastate the population." Which leads us to ask:

Challenge Question #10:
"What do you think are some natural hazards that the cranes face?"

Challenge Question #11:
"What are some reasons why the cranes leave at different times instead of all together?"

(To respond to these questions, please follow the instructions below.)

Tom expect most of the whooping cranes will start the migration between April 5 and April 15. After about April 20th, all the breeding pairs have migrated. All of us join Tom in his wish: "Safe traveling to the nine whooping cranes that have started the migration."

Riding the South Winds
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Surface Winds March 24, 2002

Tom Stehn enjoyed some great wind-surfing weather on March 24, and the first whooping crane pair probably took off on those same winds. Says Tom, "These pairs probably headed north on March 24th when it was incredibly windy on the Texas coast. That would have provided strong 25 mph tailwinds to aid the birds as they crossed Texas. With winds like that, the cranes could have flown 60 mph and crossed almost all of Texas, flying 400+ miles all in one day. The winds sure were a handful for me as I windsurfed on the bay that day. I was easily going 30 mph myself, the sail pulling me along just as the wings of the cranes act as a sail catching the wind and making their migration easier."

What made those winds blow, and blow in the right direction to aid migration speeds of an astonishing 60 mph? You'll figure it out with a close look at the weather and wind maps leading up to the March 24th take-off! We'll lead you along the way:

Try This!
Cranes normally fly between 32 and 35 miles per hour. On a day with 25 mph winds from the south, how long would it take a whooping crane to fly from the southern border to the northern border of YOUR state? What do you need to know to figure this out? (Tailwinds ADD to the bird's own speed.)

Just Hangin' Out: Field Notes from Florida
Cranes Follow Ultralight to Florida, Fall 2001 Photo WCEP
What's happening with the five ultralight-led cranes on their remote island at the Chassahowitzka National Wildlife Refuge in Florida? "They're still fat and happy, just hanging out. Not much has changed," reports ICF project biologist Matt Hayes.

How will the young cranes know when to migrate? And how do they prepare their bodies for such a long journey? Stop here and make your prediction. Then be sure to see the comments of Ferrisburgh students and Tom Stehn in the discussion of Challenge Question #8, below!

The Pressure Is On
All along their migration route, the whooping cranes that winter in Aransas NWR wait for favorable winds to fly. Will the Florida flock know this, and take off on a day with favorable weather conditions? We'll keep you posted!

Challenge Question #12:
"What makes barometric pressure so important for crane migration? How might cranes know when the air pressure is rising or falling?"

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

Clearing the Fog About Wind and Weather
How do you read a weather map? Which way does the air around a high pressure center circulate? What direction does the air around a low pressure system move? What does this all mean for birds? What makes a good day to fly? Thanks to Dr. David Aborn, you can read the weather from a bird's point of view. Although written for songbird migration, the weather principles discussed also apply to whooping crane migration:

Internal Clocks: Discussion of Challenge Question #8
"Wouldn't it be something if the whooping cranes in Florida and Texas all started the migration about the same time? It's possible, since whooping cranes have an internal clock," said Tom Stehn. He asked you: "What do you think we mean by internal clock? What clues do the whooping cranes use to set their clock to know what time they should start the migration?"

Hooray for Taylor and Genevieve, fourth graders from Ms. Thurber's class at Ferrisburgh (VT) Central School, who answered: "We think that an internal clock means that the whooping cranes can tell the time of year by instinct. The length of day is a clue to what time of year it is."

Tom Stehn confirms Taylor and Genevieve's answer, and adds this: "How do the cranes know when to migrate? It has to do with the length of the days. The cranes have an internal clock and ability to know how long the days are. (They don't have a wrist watch to tell time, but did you know they do have a wrist -- a joint located out near the tip of the wing?) How animals can measure the length of daylight is a mystery, but I know cranes can do it because I know I have an internal clock myself. How else can you explain that I usually wake up just BEFORE the alarm clock goes off, telling me it's time to go to work? How can I possibly do this unless I have an internal clock that mysteriously wakes me up? So somehow the cranes use their internal clocks and know that the spring days are getting longer. This triggers hormonal changes in the cranes, readying them for the migration. They eat more, gain weight, and build up fat reserves needed for the long, hard migration. And when the days reach a certain length, off they go to Canada for the summer."

Tick-Tock: Biological Clock
Cranes aren't the only ones with internal clocks. Each of us has our own biological clock. Explore the concept of time and your own ability to keep time. Then consider the importance of biological clocks to migratory species with five fun activities here:

Crane Adaptations: From Head to Toe
Any ornithologist seeing a crane for the first time could instantly guess that this bird lives in wetlands, flies long distances without a lot of flapping, nests on the ground, gets food from wet soil or water, and has a loud voice. How? Fascinating secrets are revealed when we study how an organism's body--and its behavior--are adapted to its environment. An "adaptation" is a physical or behavioral feature that evolved in response to an organism's environment, due to pressures for survival. How a species looks (its anatomy), as well as how it behaves (how it moves, obtains food, reproduces, responds to danger, etc.) are all based in the species' evolutionary history. This spring, we'll look at a whooping crane's body from head to toe to see just how this bird is designed precisely for the kind of life it leads. Each week, we'll pose a Challenge Question related to an adaptation that helps cranes. Remember: There's always a WHY behind WHAT you see. So whenever you see an unusual behavior or body part, ask yourself WHY. Here goes:

Challenge Question #13:
"Why is it good for cranes to have short tails?"

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

Who Gets the Water? Discussion of Challenge Question #9
"Do you feel that the freshwater needs of wildlife should be protected by law in places where water shortage is a problem? Explain your reasons."

"How self-centered can a species be to allow such possibilities to become realities? It certainly doesn't speak much for us does it?" commented Mr. Ramsden. He explains: "I am from Texas, San Antonio to be specific, and I now live in Colorado Springs, CO. The point is, water was critical when I lived in San Antonio and it is critical where I live now. We MUST, as a species, control our breeding. To double, or increase our population even 10% is just irresponsible. We cannot increase infinitely with finite resources. What quality of life can we expect if we DOUBLE our population? Who hasn't grown impatient waiting in lines, fighting crowds, putting up with just plain rudeness from people that are calloused over from putting up with cell phones going off in theaters and Churches?"

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 (OR #11 OR #12 OR #13).
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 9, 2002.

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