Tom Stehn Reports from Aransas: April 16, 2003 Tom Stehn and Survey Plane Dear Journey North: It has happened, and all in a hurry. Between April 10th and April 15th, 114 whooping cranes started the migration from the Texas Coast. This is more than half the flock of 184; 62% to be exact, all heading north in a period of 6 days. I only found 7 cranes at Aransas on my census flight on April 15th. After a cold front and unfavorable migration conditions April 7-9, the winds in Texas turned around from the southeast and strengthened, getting progressively better for migration each day between April 10 and April 15. Two cranes were sighted in Central Texas on April 11, indicating they had probably left Aransas on the 10th. Three cranes were sighted leaving the refuge on April 14, by which time most of the cranes had already migrated. Since the migration has started, 96% of the flock has headed north. I?m pretty close to having an empty nest with just 7 whooping cranes to search for next week. This is true in my own house also, with my two sons both in college. The migration appears to be on schedule, with all the adult cranes having headed towards the nesting grounds. The adults feel the urgency to build a nest, lay eggs, and raise young in time to migrate south ahead of winter. The 7 cranes remaining at Aransas are all cranes too young to breed, including one chick that had separated from its parents earlier in the winter. The crane I have been watching all winter with the drooping left wing has apparently started the migration. This does not surprise me since it had migrated south last fall with the injured wing. The wing is not hanging down as far as it was earlier in the winter. It has gotten better, and the crane has been observed flying normally. Last week I asked you how cranes manage to spend 2-3 weeks migrating, and then 4 weeks nesting and sitting on eggs, with not enough time to spend finding food to eat. The answer has to do with fat reserves. Prior to the spring migration, the cranes gain weight, eating more and storing energy in the form of body fat. That is why it is so important to have lots of blue crabs available in the spring at Aransas to enable the cranes to build up these fat reserves. The cranes have to endure the hardships of long migration flights, feeding only a little each day in the morning and evening. Perhaps the cranes will get up to Canada when it is still frozen and find little to eat. Then they have to take turns with the male and female both spending time sitting on eggs and not having time to search for food. Through all these hard times, the cranes rely on their fat reserves and slowly use them up. In this way they can survive to make another migration and raise another young next year. Since most adult cranes nest every year, why do you think the whooping crane population has grown so slowly and is still endangered? Until my next update; enjoy the spring. Tom Stehn, Whooping Crane Coordinator U.S. Fish and Wildlife Service Aransas NWR P.O. Box 100 Austwell, TX 77950 Copyright 2003 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form