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Whooping Crane Migration Update: March 28, 2000

Today's Report Includes:

Romance on the Platte?
Two of the Aransas/Wood Buffalo flock of whooping cranes are together on the Platte River in Nebraska with the main migration just about to get underway. Wally Jobman reports that the second bird showed up on March 8. Where did it come from? Wally says:

"No way of knowing where this bird wintered, whether it decided to leave Aransas early or wintered with sandhills in an unknown location. . . .It will be interesting to see if they develop a relationship."

We'll just have to wait and see! In the meantime, we wonder:

Challenge Question #8:
"Do bonded cranes, who mate for life, ever split up? If so, why?"

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

Tom Stehn Reports Latest News from the Wintering Grounds

Aransas National Wildlife Refuge
Austwell, Texas
March 27, 2000

Dear Students:
An aerial census of the Aransas National Wildlife Refuge and surrounding areas on March 25, 2000 located 185 whooping cranes. The population this winter reached a record 188. In addition to the 185 presently at Aransas, two whooping cranes have been confirmed in Nebraska on the Platte River. One whooping crane, a color-banded adult female died around the end of December. She was 13 years old. This accounts for all 188 whooping cranes in the Aransas/Wood Buffalo flock.
Cranes Waiting: No April Fools!
A few whooping cranes usually start the migration the last week in March, so I anticipate a slightly lower count on my next flight. Most of the whooping cranes wait until April before they start the migration. This is very different from sandhill cranes that leave earlier and then "stage" in March on the Platte River in Nebraska where tens of thousands gather and spend weeks together. This year, the two whooping cranes that are currently in Nebraska presumably joined sandhills and migrated early. Whooping cranes never migrate in large groups. Instead, they usually travel in groups of 1 to 5 birds." This makes us wonder:

Challenge Question #9:
"Do family groups of cranes migrate together?"

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

Good News for Crabs 'n Cranes
Tom continues, "Habitat conditions have recently improved at Aransas. Rains have lowered salinities just enough so that the cranes are drinking out of the marsh and not having to seek out fresh water. High tides have re- flooded the marshes, with some blue crabs once more available for the cranes. Hopefully, feeding the last month at Aransas on crabs, which are very high in protein will provide the cranes the fat reserves they need to make the long 2,500-mile migration that can take up to a month. They will need this energy to nest as soon as they reach Wood Buffalo National Park in the Northwest Territories of Canada."

Tom Stehn
Whooping Crane Coordinator
Aransas National Wildlife Refuge
Ready, Set, WAIT: Tips for Tracking the Take-Off
Last time we gave you a logsheet so you're ready to track the 188 cranes as they leave Aransas. It's not easy to count cranes from the air! Tom says the migration has not yet begun, but last time his aerial census spotted only 159 cranes. Why? Tom explained why those counts were down:

"Counts going down wasn't because of the migration. Factors such as visibility during the flight, flight length (i.e. search effort), bird movements, etc. all impact total numbers counted. On a recent flight, smoke from a prescribed burn curtailed my search effort."

Stay tuned! Next week the migration should be underway, and we'll start giving weekly crane countdowns. THEN you can record results on your logsheet:

Sad News: One Loss
Speaking of counting cranes, we have some sad news. A Rocky Mountain whooping crane was found dead on March 15 after it collided with an electrical powerline at Monte Vista NWR. For years, this whooping crane had been negotiating the low powerline next to the main highway through the refuge. The crane wintered at Bosque del Apache NWR and summered in Yellowstone.

The crane was an 18-year-old female hatched from one of several eggs transferred into the nests of sandhill cranes between 1975 and 1989 in an experiment to establish a whooping crane population in the Rocky Mountain area. The sandhill cranes raised the hatched whooping cranes as their own. Now just two whooping cranes remain in the Rocky Mountains. One is in the San Luis Valley and the other was recently sighted at Ouray NWR.
High Hazards
Kelli Stone, a biologist at the Alamosa/Monte Vista National Wildlife Refuge Complex, told the Coloradoan newspaper: "The death...illustrates the difficulty some wild creatures have in today's world of development and wetland modification and loss."

Tom Stehn said, "It seems appropriate that USFWS get this line buried since many cranes cross it annually." After reading the remarks of Kellie and Tom, don't you wonder: What other dangers do cranes face during their long migration?

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

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

Try This! Watch for newspaper reports during the cranes' spring migration to see if other crane fatalities are reported. Keep track of any deaths to these huge but fragile creatures, along with the causes. Then see what you can learn about efforts to protect cranes along the migration route.
Oil Spoils
Many efforts are in place to protect the endangered wild whooping cranes. But how safe are the wintering grounds? If you look at the map of Aransas, you'll see that it is next to an intercoastal waterway with heavy commercial barge traffic. What risk does this mean for the whooping cranes and their food supply? What would happen at Aransas if an oil spill occurred? Journey North asked Tom Stehn this question. Tom answered:

"We have a plan, but it has severe limitations. We store oil spill booms on the refuge and have staff trained to place short booms across water cuts into the marsh areas. Trained contractors are available to be on the scene in three hours to place many more booms.

"Limitations are that chemical spills may take place 100 yards away from whooping cranes and marshes can be contaminated even before a phone call reporting the spill is made. Secondly, booms are only partially effective in high wind situations, and Texas is very windy. Third, some chemicals are so toxic that only people dressed in protective suits can approach. In those cases, we will basically be evacuating the area and be more in a clean-up situation.

"If salt marsh gets spilled upon, cleanup can do more harm than doing nothing. There is no technology to clean up salt marsh.

"The spill issue is a huge problem that the whooping cranes face. We looked at re-locating the Intracoastal Waterway, but it was not feasible and could even have led to increased spills in other areas."

Challenge Question #11:
"What aspects of cranes' normal behavior could cause problems if an oil spill occurred at Aransas?"

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

Why Fly? Discussion of Challenge Question #4
Last time we asked, "When do young whooping cranes leave their parents for the first time? And since migration is so dangerous, why do you think the juveniles migrate 2,600 miles to the north if they're not going to nest?"

Brian Johns, based at the cranes' Canadian nesting grounds, explains:

"Young Whooping Cranes stay with their parents for almost 1 year. Young cranes may separate either during spring migration or after migration is complete. As the cranes migrate north there is more courting behaviour between the parents and a young crane is sometimes driven out of the family group. Whenever there are cranes summering in southern Saskatchewan or Alberta they are usually the young from the previous year that have separated from their parents in those locations. Young that do not separate from the parents during migration will separate upon arrival on the breeding grounds. The adult birds do not tolerate other cranes on their territory, not even their young from a previous year.

"Juveniles usually summer in the vicinity of the breeding grounds in Wood Buffalo National Park unless they summer in southern Saskatchewan or Alberta. Cranes migrate back to the place they migrated from, and that is the breeding area in the park."
Solo Whooper: Discussion of Challenge Questions #5 and #6
Challenge Question #5 asked: "How can you tell the difference between an adult plumaged whooping crane and a juvenile or young-of-the-year crane?"

We got this answer from Ohio: "You can tell the difference between the adult Whooping Crane and the juvenile Whooper by their plumage. The juvenile Whooper has brownish colored plumage whereas the adult Whooper has white, red and black plumage." (burrad08@mechanicsburg.k12.oh.us)

Wally Jobman added: "A juvenile crane (defined as a young-of-the-year) is rusty brown during the fall migration. During the winter it loses most of the brown coloration, and looks similar to adult cranes during the spring migration. However, during the spring migration there are still some rusty colored feathers on the head, neck, and back of the young bird."

Challenge Question #6 was: "Why might a whooping crane choose to winter with sandhill cranes?" Wally Jobman's thoughts might spark more of your own. He said:

"We speculate that in most cases the whooping crane was separated from its parents during the fall migration before reaching Aransas. The young bird became confused, joined with sandhill cranes, and went to their wintering area. If a young whooper does not make the initial migration to Aransas with its parents, it has no way of knowing where Aransas is. Migration is a learned behavior in whooping cranes. As the young bird gets older during subsequent migrations, and does not join other whooping cranes, it will continue to winter with sandhills. So, it is not normal for a whooping crane to winter with sandhills."
More Adaptations: Discussion of Challenge Question #7
"Name at least one other adaptation of a whooping crane's body. Why do you think it has that adaptation?"

Have you ever craned your neck to see farther? Can you demonstrate what that expression means? And why is this movement called "craning" your neck? This probably got you thinking about the l-o-n-g neck as another crane anatomy-and-adaptation feature. Brian Johns points out why wading birds such as cranes have long necks. "The cranes need these long necks to compensate for their long legs. Since the long legs raise the body high up off the ground, the long neck enables them to reach back down to the ground or into the water to pick up food with their bills."
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 #8 (or #9 or #10 or #11).
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 4, 2000.

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