Whooping Crane Migration Update: April 4, 2000

Today's Report Includes:

A Whoop of Welcome
Great news! There are two more Whoopers in the World! The first whooping crane chicks to hatch in the United States in 100 years popped through their eggshells March 16-18. When you're trying to save an endangered species from extinction, success sometimes comes in baby steps, or at least one baby bird at a timeń-and wildlife biologists are ecstatic.

The chicks are not part of the Aransas/Wood Buffalo migratory flock, but were born into the world's second whooping crane flock. Surprised? This flock's home is in Florida and is the result of the reintroduction of non-migratory whooping cranes that started in 1993. Read more about the world's second flock of whooping cranes, and find out why the hatching of the chicks is a milestone worth celebrating. See:

Then see if you can answer:

Challenge Question #12:
"How many whooping cranes were in the reintroduced flock as of March 29, 2000?"

Tom Stehn's Crane Countdown
 Migration Route Map by Claudia Fonkert Macalester College
Tom Stehn lets us in on the Crane Countdown. Today's letter says:

Dear Journey North,

"Well, April has arrived and the whooping crane migration is underway. I did a census flight on March 30 and found 169 cranes. Figuring that I overlooked some, I'm estimating that about 12 cranes have started the migration since my last flight on March 25. Two cranes had migrated about a month ago and were found in Nebraska March 2 - 8. Thus, 14 total whooping cranes have migrated. Departures should pick up rapidly this week and especially next week. Looks like things are about on schedule."

Challenge Question #13:
"This is only ______ % of the flock." (Calculate and fill in the blank.)

Lonely Chick?
"The most interesting thing about the census fights was finding a chick all by itself on the refuge. Apparently its parents started the migration and left the chick behind. This happens occasionally. Normally the parents will migrate with their chick back to the nesting grounds in Canada. Sometimes the chick splits off on its own in Saskatchewan. This separation of the chick from the parents seems to occur primarily because the youngster is growing more independent. Late in the winter, the chicks are sometimes feeding quite a distance away from their parents rather than remaining underfoot and begging for food as they do when they first get to Aransas in the fall. We've never observed adults driving off their chick. It just seems like the chick realizes it is time to be on its own."

Challenge Question #14:
"What do you think will happen to the chick left behind at Aransas?"

"So why would the parents want to migrate and the chick not be ready? It's kind of like your parents packing for a trip and the kids watching TV instead of getting their things together. With the cranes, it all has to do with hormones and the urge to breed. The adults are going through hormonal cycles that get them interested in making the migration and returning to Canada to nest. Since the chick is too young to be undergoing these changes, it does not have the same desire to head north so soon. Imagine the conversation between parents and chicks as the parents spiral up in to the sky, whooping to all the other cranes as they depart. And the chick responds back: "Hey! Where are you going?"

I'm looking forward to my next flight on April 7 to see how much the migration has advanced.

Tom Stehn
USFWS Whooping Crane Coordinator
Aransas NWR
Austwell, Texas

Up, Up and Away
Usually family groups travel by themselves. Sometimes they happen to arrive at the same staging or resting area as other cranes. When this happens more than one family group may be seen together. When the family groups migrate from these staging areas they either do it as single family units (most often) or as larger flocks that may include another family (less often). Most often these larger flocks contain only one family group and two or three other cranes. Which leads us to:

Challenge Question #15:
"What might be some advantages for whooping cranes to migrate in very small groups rather than big flocks?"

Try This!
How distinctive are voices for identifying other people? Check it out by blindfolding a volunteer. Record results as the volunteer listens to five different voices in turn and tries to name the correct speaker for each. Then read on. . . to find out who gives a whoop!

Who Gives a Whoop?
Volunteer crane researcher Dr. Bernhard Wessling, who lives in Germany, recorded about 20 crane unison calls and an equal number of guard calls at Aransas during ten days in December 1999. About 15 crane pairs gave both vocalizations. Dr. Wessling wants to see if the two calls are related. He will need to analyze sonograms to make certain they are unique. This technique has great potential for "marking" pairs, but you can imagine how difficult it is to get the recordings! What do whooping cranes sound like? Listen to the cranes' call courtesy of the International Crane Foundation:

The whooping crane's name was inspired by its loud, distinctive call, audible up to two miles away. Wally Jobman says, "It has been my experience that whooping cranes do very little calling during migration. They will often call when they take flight, but do little calling during migration flights." This makes us wonder:

Challenge Question #16:
"What feature of a crane's anatomy enables the call to be so loud? And what are some reasons why cranes call?"

Migrating Families: Discussion of Challenge Question #9
Last time we asked if families migrate together. You read part of the answer above (See Up, Up and Away). Here's more:

The young usually depart the wintering grounds with their parents. The subadult birds (2 to 3-year-olds that are to young to breed) usually migrate after the breeding birds. The breeding pairs are the first birds to migrate north in the spring, the subadults linger on the wintering grounds longer and generally have a more leisurely northward migration. During fall migration the opposite happens, with the subadults leaving the breeding grounds before the breeding birds.

High Hazards: Response to Challenge Question #10
We asked, "What are some of the hazards that whooping cranes face on their long flight between Aransas National Wildlife Refuge and Wood Buffalo National Park?"

Power lines, storms, tornadoes, Peregrine Falcons, Bald and Golden Eagles, foxes, raccoons, wolves, coyotes, and steel leg traps are all potential hazards to cranes.

Between September 1999 and February 2000, seven deaths were recorded among the non-migratory flock of whooping cranes being established in Florida (see more about this flock above). Bobcats took five of those cranes, and alligators took two.

Oil Spoils: Response to Challenge Question #11
"What aspects of cranes' normal behavior could cause problems if an oil spill occurred at Aransas?" Tom Stehn explains: "Whoopers are territorial so it would be practically impossible to try to haze them and keep them out of a contaminated area." Because of cranes' feeding habits, their diet and health would also be affected by an oil spill.

How to Respond to Today's Challenge Questions: