Whooping Crane Migration Update: April 19, 1999
Today's Report Includes:
Whooping Cranes: Going, Going,?Almost Gone!
Whooping Cranes are almost gone from Aransas NWR. Here's the latest word from Tom Stehn:
April 13, 1999
Dear Journey North,
The whooping cranes are in the peak of their migration. I was very surprised when I did an aerial census on April 8 and found only 56 whoopers still at Aransas. Based on the timing of departures in the past, I was expecting about 100 to still be here. So the migration appears to be about one week ahead of schedule.
Full Speed Ahead!
We had very strong winds from the southeast on April 2-3, and I think many of the cranes took advantage of the tail winds and may have crossed nearly all of Texas in one day (over 400 miles). They can fly about 30 miles an hour, but when pushed by strong tail
winds, speeds of up to 60 mph have been recorded. In total, 69% of the flock (127 out of 183) has started the migration. Of the 51 pairs I expect to nest this summer in Canada, 38 are underway. These adult birds are the ones with the growing urgency to migrate since they have to get up to Wood Buffalo National Park by early May in order to nest in time.
The whoopers are spread out in their north/south corridor that is over 150 miles in width. No birds have reached Canada yet, but two whoopers have been sighted in North Dakota. I've received reports of groups of 6 and 8 birds crossing the Panhandle of Oklahoma (western edge of the migration corridor) on April 7 and 8, and then had 6 cranes seen actually east of the usual corridor in Iowa near DeSoto National Wildlife Refuge on April 9. This group had been blown off course by an incredibly strong low pressure system that produced devastating tornadoes in Ohio the following day. Iowa has had only a few whooping crane sightings in the past 50 years, whereas before that, whooping cranes once nested in Iowa. Groups of 6 or 8 are about as large as migrating flocks of whooping cranes get. They often travel in groups of 1 to 3 birds.
Is Today the Day?
The Nyarling cranes that have their territory in front of the public viewing tower on the refuge are still here at Aransas. This is allowing the public to still see whooping cranes if they visit the refuge. I expect this family of cranes to depart any day. Winds are forecast to blow from 15-25 mph from the southeast today. I bet today is the day they leave. I wish I was out there watching them pick up that last bite of blue crab for their journey.
Tom Stehn, Whooping Crane Coordinator
April 15 Aerial Report: Even MORE Movement!
Tom did his aerial census on Thursday, April 15, 1999, and found 36 adult and 5 immature whoopers. He also sent word that "On April 9-11, nine cranes were documented in southwest Iowa. They were blown out of the usual mid-Nebraska migration corridor by a strong storm that later caused devastating tornados in Ohio. Present were six cranes near DeSoto NWR, and a family group near Essex in Page County."
Challenge Question #9
"Calculate the % remaining to fill in the blanks in the table."
Challenge Question #10
"When will the first cranes reach Wood Buffalo National Park?"
Discussion of Challenge Question # 6
"What might be some advantages for a species to migrate in very small groups rather than big flocks?"
Sixth grade Jenny, in Canton, Ohio, answered, "One advantage to traveling in small groups rather than traveling in very large groups is because if there is an accident, fewer of the birds would get hurt. The cranes can't afford for a large group of them to die!" Jenny also pointed out that "It would be easier to keep track of smaller groups than in one huge group. If they were all in one big group they would have to find food for all the birds instead of just five or six. Smaller groups can fly at different rates to help the inexperienced flyers. Other groups can move at a faster rate. When they travel in small groups they can hide easier instead of being spotted by a predator which might kill some of the cranes. And it might be easier for a small group to find a place to rest."
Discussion of Challenge Question #8
"Can you think of a reason why birds face into high winds, and take off directly into headwinds?"
Kellan and Forrest, also in Jenny's class, reasoned through it this way: "We think that birds fly into the wind because if they go with the wind they'll have no control of where they are going. Also the way feathers are shaped that if a bird was to turn around the feathers would ruffle and may be damaged. If they were to turn around their tail feathers might make the bird flip over and over and it might break its bones. It might be more aerodynamic to fly into the wind."
How to Respond to Today's Challenge Question
Please respond to only one Challenge Question per e-mail message.
1. Address an e-mail message to: firstname.lastname@example.org
2. In the Subject Line of your message write: Challenge Question #9 OR #10
3. In the body of your message, answer the question.
The Next Whooping Crane Migration Update Will be Posted on April 26, 1999