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October 29, 2004
Migration Day 20

Warm Temps and Headwinds Prevent Progress

It's 65 degrees F. in LaSalle County, IL this morning. Winds from the south are blowing at 15 mph. For the fifth day in a row, the weather is against the migration taking off from this site. Colder temps are best for migration. Joe Duff explains:

"Cooler air is more dense than warmer air. Warm air can actually hold more moisture because there's more room for moisture. When air is dense and compact (when it's cold) it's thicker, so when you breathe in you get more oxygen. When you do a wingbeat there's more to push against. When the propeller spins there's more thrust. When the wing flies there's more lift to it. The aircraft works better, the engine works better, the propeller works better, the wing works better. And for the birds, their wings work better; they get more oxygen and it's easier to cool their bodies. They don't overheat.

"It's just a lot easier to fly in cold air. That's really a big factor in their endurance. Warm air just wears them out very quickly. You see them panting quickly. Their tongues come out. They start to splay their feet to help cool their bodies, and they just can't fly."


Try This! Journaling Questions
  • Describe in your journal why cooler temps make better migration conditions for both birds and ultralights.
  • Look at the migration route map. Through how many states will the Whooping cranes pass? How many of these states have you been in? Look at a detailed map of these states and see if you can guess what cities and landforms the cranes will see from above. Why do you think they migrate south into Illinois and then east across to Indiana, rather than taking a straighter, shorter line to Indiana? (Hint: What is the biggest city in any of these states? How might flying over a huge city be a problem?)


Journey North is pleased to feature this educational adventure made possible by the

Whooping Crane Eastern Partnership (WCEP).

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