Tom Stehn Reports from Aransas: March 22, 2002 Dear Journey North, Tom Stehn and Survey Plane The whooping crane migration is about to start, but I believe we have one bird over the starting line a little early. On March 19, one whooping crane was sighted on the Platte River in Nebraska mixed in with tens of thousands of sandhill cranes. Is this bird color blind, not realizing he is with sandhills and not other whooping cranes? I think NOT. Sometimes whooping cranes travel with their sandhill crane cousins, often stopping where they see a flock of sandhills on the ground. This one whooper was apparently influenced to start the migration with the large flocks of sandhills that migrate more than a month earlier than the whooping cranes." The reason for the earlier migration by sandhill cranes is that they stop on the Platte River and hang out in huge flocks for a month or more. This is called a "staging" area where the sandhills socialize and form pairs. The large flocks of up to half a million sandhill cranes on the Platte River in March are a natural wonder of the world. (Whooping cranes when they migrate don't stop at a staging area. They keep on trucking all the way to their nesting grounds in Canada.) I was very surprised when I heard about the one whooping crane in Nebraska. Had others left their winter home at Aransas as well? I climbed into a small airplane on March 21 and spent eight hours flying 1/4-mile wide transects across the salt marshes, viewing every square foot of the marsh and plotting all the whooping cranes I found on color photographs of the area. I located a total of 172 whooping cranes. The one in Nebraska makes 173. Thus, there is only one whooping crane that I cannot account for of the winter population that totals 174. It could have started the migration, it could still be at Aransas and I just didn't find it, or else it could be dead. My census clearly showed that only one out of 173 whooping cranes is known to have started the migration. That's less than 1 % of the population. By the end of March, I expect several dozen whooping cranes will be flying north, anxious to start their 2,500-mile trip to Canada where they will build nests, lay eggs, and try to raise chicks. If I found 172 whooping cranes on March 21, how many do you think I'll find on my next flight March 28th? We also are watching five whooping cranes in Florida that last fall were flown behind an ultralight airplane from Wisconsin to Florida. Although we are confident these five will return to Wisconsin on their own, we don't know when they will migrate. I've been telling our biologists not to be concerned until mid-April. That seems to be the time when many of the whooping cranes leave Texas. Wouldn't it be something if the whooping cranes in Florida and the ones in Texas all started the migration about the same time? Its possible, since whooping cranes have an internal clock. What do you think I mean by "internal clock?" What clues do the whooping cranes use to set their clock to know what time they should start the migration?" Tom Stehn Whooping Crane Coordinator U.S. Fish and Wildlife Service Try This! Journaling Question What do you think Tom means by "internal clock?" What clues do the whooping cranes use to set their clock to know what time they should start the migration? Copyright 2002 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form