Tom Stehn's Report: Early Bird Heads North
March 11, 2011
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As you read Tom's report this week . . .
  1. Why did one whooper leave so early?
  2. How does the migration of whooping cranes differ from the migration of sandhill cranes?
  3. When do the whoopers at Aransas NWR normally start migration?
  4. How many hours has Tom's spent in the air counting cranes in his years at Aransas NWR? Is it more or less time than one of your birthdays to the next?



Dear Journey North Kids,
Find the early whooping crane migrating now with sandhill cranes.

At least one whooping crane has started the migration! It was confirmed on March 1 in a flock of about 10,000 sandhill cranes near Pampa, (north of Abilene) in the Texas Panhandle. This crane never wintered at Aransas, but instead chose to stay with sandhill cranes in north Texas.

Migration Timing
Yes, that whooper is starting the migration early, but it is timing its journey to match that of sandhill cranes. Sandhill cranes start the migration about a month ahead of whooping cranes. This is because the sandhills get up to the Platte River in Nebraska and stage, or gather by the hundreds of thousands. They feed, fatten up, and search for mates. You can see and hear this spectacle of migration on the crane cam at Rowe Sanctuary on the Platte River near Kearny, Nebraska.

Whooping cranes do not have a staging period in their spring migration. They don't need to stage since they already have mates and (we hope) are already fat from eating blue crabs all winter.

When Will the Whoopers Leave?
One year I suspected the Lobstick pair (you met them in the slideshow last week) started the migration from Aransas about March 3. That's the earliest suspected record that I have. Many whooping cranes at Aransas wait until at least March 25th before they migrate, and most wait until the first week in April. However, the handful of whooping cranes that wintered with sandhill cranes away from Aransas have all started the spring migration early and may actually reach the Platte River in Nebraska before the first whooping crane has left Aransas.

Latest Aerial Count at Aransas: Two Losses
On March 1 I flew this winter's sixth aerial census over Aransas. Observations confirmed the loss of two additional whooping cranes, so winter mortality in 2010-11 has totaled 4 cranes (3 adults and 1 juvenile). That brings the current estimated flock size to 279. (The peak size of the Aransas flock this winter was 283.)

I have no idea on the cause of death for any of the 4 losses this winter. Its always frustrating, since we rarely ever find a carcass. But I take consolation that I'm one of the few people that could even detect the mortality, so their deaths did not go unnoticed.

Someone Else's Turn
I'm really hoping and planning that March 1st was my last census flight. It's time to step aside and let the "youngsters" get experienced. I've done 29 winters of aerial observations, 544 flights, and 3,448 hours in the air. So for the rest of the spring, I hope Brad Strobel will be in the front observer's seat, and I'll stay on the ground!

Tom Stehn
Aransas National Wildlife Refuge
Austwell, Texas