Tom Stehn's Report: Migration Has Begun!
March 12, 2010
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As you read Tom's report this week . . .
  1. What is remarkable about the crane that has begun migration?
  2. How has the habitat improved for the cranes?
  3. Explain Tom's example of "nature's perfect timing" helping the cranes.

Dear Journey North,

The migration has started. This is the earliest migrationstart on record (except for birds that had a history of separating from their parents as juveniles wintering with sandhills away from Aransas). A single white-plumaged Whooping crane was seen at Salt Plains National Wildlife Refuge in northern Oklahoma February 24-26. Since we didn't know of any other white-plumaged Whooping cranes in the Flyway this winter, this must be a case of a whooper on the Texas coast getting influenced by sandhill cranes and starting the journey ahead of the normal schedule for Whooping cranes. We'll never know, but it could be the single bird sighted at Mad Island on 1/17/10. This seems possible to me since it was wintering by itself around sandhills. No other Whooping cranes are believed to have left Aransas. This crane left Salt Plains NWR on March 5. Look at the Journey North crane map and you'll see the new location!

Nature's Perfect Timing
The main update I have regarding Aransas is that conditions have gotten better for the cranes. The tour boat captains first noticed this starting the last week in February. As higher tides pushed water back into the marshes, a few crabs left the bays and moved into the crane marshes. It became worthwhile for the cranes to resume searching for crabs, and they had some success chowing down on their favorite food. With the approach of spring, the cranes start putting on weight just as foods in the marsh become more abundant. This boost of energy and protein is very important for the cranes just prior to the rigors of the migration and upcoming nesting season. The hormones of the cranes change starting this time of year. That change actually allows them to gain weight. Nature times it perfectly, which demonstrates just how well animals have to be adapted to their environment in order to survive.

Good Numbers!
I flew the seventh aerial census of the 2009 -10 Whooping crane season on March 9th. With one juvenile last seen in Oklahoma December 25th that apparently separated from its parents during migration and is presumably okay and wintering in an unknown location, and the chick that died at Aransas earlier, this accounts for all 22 of the 22 juveniles found in Canada during the mid-August fledging surveys. With the one documented death this winter, the current flock size is estimated at 242 adults+ 21 young = 263.

Tom Stehn
Aransas National Wildlife Refuge
Austwell, Texas