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Whooping Crane Migration Update: March 27, 2001

Today's Report Includes:

Tom Stehn Reports from Aransas

"Dear Journey North,

My best way of monitoring the whooping crane population is on weekly aerial census flights when I try to find all the whooping cranes and plot their location and type of habitat they are using. We fly in a Cessna 172 high-wing aircraft at about 90 miles per hour just 200 feet above the ground. Using a Global Positioning System (GPS) unit that tracks our path, we fly precise transects about 3/8 of a mile wide until, about 7 hours later, we have seen all the salt marsh where the whooping cranes winter. I plot all the crane locations on aerial photographs that help me make sure that the whooping cranes aren't moving around during the census flight and being counted twice. The flying is done by Dr. Tom Taylor, a former college chemistry professor who now flies full time. I just hang on and look for cranes.

Census flights March 15 and March 21 indicated that just about all the whooping cranes are still here. I found 171 whooping cranes the first flight, and 168 the next. Probably just missed a few on both flights. On both flights, one territorial pair was missing and could have migrated. So far there has been only one confirmed whooping crane sightins reported in the Central Flyway, another good indication that just about all the whooping cranes are still at their winter home.

I'm probably going to get one more complete aerial count of most of the cranes next week on March 29. After that, the migration will start with numerous cranes expected to depart the first two weeks in April. I'll estimate when they leave and compare it with past years to see if they depart on schedule."
Tom Stehn
Tom Stehn, Whooping Crane Coordinator
U.S. Fish and Wildlife Service
Aransas NWR

Please read Tom's complete letter here:

Then come back and answer this serious question:

Challenge Question #7:
"Why does Tom Stehn predict another poor nesting season ahead?"

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

Missing Cranes Found: Start Tracking the Departures!
Imagine how difficult it must be to count cranes from the air and avoid counting any crane twice! Tom sent us a count after his March 15 flight, which was a clear-weather day. He said, "An aerial census of the Aransas NWR and surrounding areas made 15 March, 2001 estimated the number of whooping cranes present at 166 adults + 7 young = 173. It is estimated that possibly 3-7 cranes have started the migration. Here's a recap of cranes observed (171):

Location

# Cranes Observed

Refuge

50 + 2

Lamar

4

San Jose

32 + 2

Matagord

54 + 3

Welder

24

Total

164 + 7 = 171

Note: The 57 cranes on Matagorda ties the all-time high.

Map of Aransas Refuge
This is a good time to start recording the cranes at Aransas using our handy logsheet:


You super-alert readers will remember that in our March 13 Update, Tom reported 147 + 7 = 154 whoopers and guestimated as many as 10 whooping cranes may have started the migration. He later found that this count was erroneous. Read Tom's full report from March 15 to find out why.


Tales Told by Crane Voices
Great news! Dr. Bernhard Wessling has finished analyzing all the whooping crane calls recorded in the winter of 2000/2001. He learned some surprising things about the world's only wild flock of endangered whooping cranes. His findings include the promise that we will be able to follow a 22-year-old banded male--who had lost his band during breeding season last year--to the end of his lifespan. Read Dr. Wessling's report here:

Then come back and answer this Challenge Question:

Challenge Question #8:
"___ whooping crane pairs have been found back again and matched with their calls from Winter 99/00.
___ whooper pairs (20%) have significantly shifted their territory.
___ pairs have a new mate."

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

Teacher Tip: Flight Plans
Whooping cranes stand almost five feet high. They are the tallest birds in North America. How does such a large creature get up in the air, stay up as long as it needs to, move in the direction it wants to go, and come back down safely? Just about every part of a bird's body is specially adapted to help the bird fly. Can you design a crane that can glide? Have a contest to see which paper birds stay aloft the longest, and which fly the farthest. Find out about crane adaptations and how cranes fly in this six-part, in-depth lesson to help you discover how birds fly:

NOTE: This lesson also gives the help to answer Challenge Question #9, below.

A Closer Look
Many people confuse herons and cranes. One big difference is in how they fly. A heron pulls its neck into a crook while it flies, while a crane flies with its neck outstretched.Why do you think these two bird families fly in different ways? It helps to consider the center of gravity for these birds, as well as the foods they eat and how they catch their food. You'll need to do a little research, and don't forget to see our flight lesson (in Teacher Tip above) for help.

Challenge Question #9:
"How would you explain the reasons why herons fly differently from cranes?"

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

Whooping Cranes in flight.

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

Watching for Whooping Cranes

Migration Route
Map by Claudia Fonkert
Macalester College

Crane biologist Wally Jobman, our reporter on the Platte River in Nebraska, announced the spring's first confirmed sighting of a whooping crane. The single whooper with sandhill cranes was confirmed on March 23, four miles east of Kearney on I-80 and .25 miles north.

Meanwhile, teacher Gayle Kloewer from York Nebraska tipped us off to a story published March 5 in a Nebraska newspaper. Called "Crane Stakeout Planned," it announces a plan for two planes to fly over the Platte River between Grand Island and Lexington, NE every morning from March 18 to April 30. Aerial observers will look for whooping cranes roosting or spending the night on the river. Wally Jobman pointed out, "You can depend on sandhills stopping here in the Platte Valley for five to six weeks, but the whooping cranes--you never know where they're going to stop." If observers in the airplanes spot whoopers, they will contact professionals on the ground. Those folks will try to find the birds and follow them to learn more about the areas they prefer and their behavior. Also reporting sightings to the professional crews will be volunteers participating in a new, land-based Whooper Watch program developed by the Nebraska Wildlife Federation and the National Wildlife Federation.

We know that migratory species depend on good habitat all along their migration routes, as well as on their breeding grounds and wintering grounds. Nebraska, Wyoming, Colorado and the U.S. government have been working together to share responsibility for meeting the needs of whoopers and other species along the Platte River. The central Platte is thought to be a key stopover for whoopers and has been named as a habitat critical to their survival. Some biologists believe that dams and irrigation projects upriver have harmed that habitat, and that's the reason for the Whooper Watch program. Ms. Kloewer said, "I hope this is a good idea and won't cause the birds undue stress." What do YOU think?

Could These Be Whoopers?
Every year somebody sees a beautiful white bird with black primaries flying at a distance, and jumps to the conclusion that it must be a Whooping Crane. Usually it's really a Snow Goose or an American White Pelican. Sometimes a pale Sandhill Crane looks as if it had dark primary feathers, like a whooping crane. There were only 176 Whooping Cranes wintering in Aransas, Texas, this winter, along with millions of pelicans and geese. So it's not very likely that a large white bird with black primaries would be a Whooping Crane.

BUT those Whooping Cranes do have to be SOMEWHERE when they're flying from Texas to Wood Buffalo National Park in Canada. Sometimes a lucky person is looking up at exactly the right time. Notice the locations of some unconfirmed reports received so far:
  • March 1, 2001, 2 possible whooping cranes seen in Naperville, Illinois, 27 miles west of Chicago, on a sunny day.
  • March 13, 2001, River Edge Nature Center Director, in Saukville, Wisconsin, saw a pair of cranes that appeared to be whoopers at 7:55 AM.
  • March 13, 2001, in Saukville, Wisconsin, in the afternoon of the same day, a different observer saw 2 whooping cranes flying low.
  • March 17, 2001, in Dakota City, Minnesota, birders reported seeing 3 Whooping Cranes flying over.

Could these cranes be part of the Florida group that biologists have released in hopes that they will eventually grow independent and wild? Or could they be part of the Aransas flock? Are they actually whooping cranes? Read on for another mystery!

Mystery of the Missing Sandhill Cranes
In our February 27 report we told you all about Operation Migration and the captive-raised sandhill cranes that were led south last fall by an ultralight aircraft. This project taught the cranes to migrate. It was in preparation for the release of an experimental migrating whooping crane population in 2001. Ten of the 11 cranes left Florida back in February. They disappeared and no one knew where they went. It seems that these important sandhill cranes are still missing. The USFWS is not concerned as yet, as the birds were raised to be wild and wild birds don't give notice when they're about to take off. The USFS expects the missing cranes to turn up soon. You can help by keeping your eyes on the skies! The birds should be returning to their rearing area in Necedah National Wildlife Refuge near Tomah, Wisconsin. 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 radio transmitter on the right leg and colored bands on the left leg. It is possible they will be traveling as a group rather than single birds.
The missing sandhill cranes are all part of the larger Whooping Crane project. You will hear more about that in our next report. In the meantime, the Whooping Crane Eastern Partnership Web site gives more information about the missing cranes and the whooping crane project in general:

Food Shortage and the Migration: Discussion of Challenge Question #4
Last time Tom Stehn asked how the lack of food this winter might affect the spring migration: "If foods are short on the wintering grounds and the whooping cranes are not getting enough nutrition (as is the case this year), in what way will the migration be affected?" These were the four possibilities Tom thought of:

a) The birds will leave early hoping to find more food during the migration.
b) The birds will leave late since their energy reserves are not sufficient for the trip.
c) The birds will leave on time since the migration is governed by daylength and not food.
d) Some of the birds won't migrate at all due to illness.

Seventh graders from Iselin Middle School grappled with this one.
"We believe the answer is 'C.' The birds will leave on time since the migration is governed by the day length and not food, because migrating is by instinct and the birds have no control over that," said Ryan, Aisha, Nicole, Nihar, Hemant, and Sean.

"Our group thinks 'B' is the answer," reported Dana Alice, Zshamani Kevin Tim. "The birds will leave late since their energy reserves are not sufficient for the trip. Since there is a food shortage, there is insufficient energy levels for their bodies. Therefore, they would tire very easily if they started out on time. The cranes have to wait longer so they can gain enough energy to migrate."

Good thinking, all of you! Here's what Tom said: "My guess is c) the birds will leave on time. 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.

"If you chose either b) and d), I might have to agree with you. Some crane researchers believe the cranes will tend to leave on the late side when their energy reserves are low. And it is certainly possible that one or two cranes may not migrate at all due to illness, or for some other unknown reason. The only answer I would disagree with is a). I don't think the birds would leave early to find more food since seeking food is not a motivation for migration. And even a poor food winter in the Texas coastal marsh would have more food available than a frozen marsh or wheat field in North Dakota."

Crane Numbers: Answer to Challenge Question #5
"What percentage of this year's nesting attempts produced a young whooping crane that safely arrived on the wintering grounds? How does this percentage compare with the average?"

Brian Johns said, "This year, 18% of nesting attempts produced a young that safely arrived on the wintering grounds." (Although 30 chicks were present in June, only 9 completed the 2,500-mile migration and arrived at Aransas. In addition, two of the 9 have died at Aransas this winter.) The average number of nesting pairs that successfully bring a young to Texas is about 46%, so 18% is way below average. The lowest has been 12%.

What Do You See? Discussion of Challenge Question #6
Tom Stehn and Brian Johns At Work. Photo Courtesy Brian Johns.
"Look carefully at the ground in this photo. What do you think Tom Stehn (left) and Brian Johns have found?"

Jenny, Dan, and Danielle from Iselin Middle School/grade 7 said, "I believe that they found a cranes nest because of the high protective grasses." Nihar, Ryan, Nicole, Aisha, and Hemant agreed.
That's a reasonable guess! But Brian Johns, crane biologist at Wood Buffalo National Park, said, "This photo is of Tom Stehn and I picking up feathers and other remains of either a dead crane or pelican. Tom sent the remains to the Smithsonian for positive identification." Bernhard Wessling was also on the scene. He added, "We found it when we were recording cranes. We had approached certain crane territories by boat. When returning, we saw the feathers and some bones and a skull. Tom and Brian were not sure whether the remains were from a white pelican or from a Whooping crane. The Smithsonian confirmed that it was a whooper. Tom says it is very unusual and improbable to ever find a dead bird in such a huge wilderness area. There are enough coyotes and turkeys and black vultures to eat the rest of it, and the inedible portions were found."

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 7 (or #8 or #9).
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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