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Tom Stehn's Report: Counting Cranes & News
Feb. 11, 2011
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Special cake, special day! Click for the story.

As you read Tom's report this week . . .
  1. How many cranes were at Aransas NWR when Tom first counted them in 1982? How many are there today?
  2. What does Tom do to count the cranes over 54,600 acres?
  3. What crane news is good? What news isn't?

Dear Journey North Kids,

Guess Who's Here?
Photographer Diane Loyd captured something she'd never seen before: a juvenile crane playing with a hunk of seaweed at Aransas NWR. The young bird and its parents had migrated more than 2,500 miles from the summer nesting grounds in Canada, where there is no seaweed! What actions is the playful crane doing as he learns about seaweed? It looks like the Seaweed Stomp-and-Catch…

Counting the Cranes: Not Easy
Every winter, my most important goal is to figure out how many whooping cranes are in the Aransas-Wood Buffalo flock (Western flock) that winters on the Texas coast. I fly with the pilot in a small aircraft and try to find every whooping crane.

The whooping cranes in winter, as in summer, are spread out over a range of about 50 miles. We methodically fly transects about 5 miles long by 1⁄4-mile wide until all the crane winter range (about 54,600 acres!) is covered. This takes about 8 hours. I plot all whooping cranes sighted on 9 aerial photos of the crane marshes attached to a clipboard on my lap. Research has shown that on average, we find about 95% of the flock on any given flight.

It's not as easy as it sounds. We have thousands of white objects to sort through at Aransas. I sometimes think that every white pelican, great and snowy egret for miles around flies to Aransas every week just to get counted. Throw in the occasional piece of white styrofoam trash washed up into the marsh along with white refuge boundary signs, and it's hard for our to find all the whooping cranes. At least there are no trees at Aransas. In fact, Aransas salt marsh is unique: Nothing here is taller than a 5-foot whooping crane, the tallest bird in North America. The cranes have no place to hide from us at Aransas.

Still, the cranes have figured out how to throw off my count. We can spot a pair of cranes, only to have them take off and fly up to 3 miles to a prescribed burn to feed on acorns — or to a freshwater pond to get a drink. That is why we fly often and wait until we get consistent counts before the final tally for the flock size is announced.

How Many Cranes at Aransas Now?
At this point I'm estimating 270 cranes but I think there are more. We celebrate the 45 chicks that are here. But I'm worried about flock mortality until the time comes that I can find more than 270. With the summer's good nesting and zero mortality, we could have been at 263 + 45 = 308 whooping cranes—WOW! (But there is always some mortality between spring and fall.)

Serious News
Migratory whooping cranes have made a remarkable comeback from only 15 birds in 1941, but one thing that makes my job so fascinating is that no one knows how this comeback story is going to end. Only with continuing efforts to protect the species and provide the habitat that it needs can we expect the species to survive for generations to come. In the latest news:

  • The new Eastern flock has grown from zero to 107 in its ten years. But many challenges are many and the latest peril is guns. Three of the Direct Autumn Release chicks were shot in Georgia in December. In January, one of the new flock's good fathers (#412), was shot in Alabama. All four deaths are under investigation, with reward money offered. An agency you may not know about is helping:
The Forensic Laboratory of the US Fish & Wildlife Service is the only lab in the world dedicated to crimes against wildlife. Scientists at the lab in Ashland, Oregon are examining crane #412's carcass in hopes of turning up more clues.
  • In better news, we are starting a new nonmigratory flock in Louisiana this month! We hope to have the Windway Corporation fly 10 young whooping cranes from Patuxent WRC in Maryland to White Lake, Louisiana. This location is where the species last nested in 1939. The last of that flock was wiped out by a hurricane, so these whoopers will be the first in many years. That flight is scheduled for February 15th, weather permitting. Sara Zimorski has moved there to take charge.

The best news is that I expect a record-tying or record-breaking year for the Aransas flock. Stay tuned! In my next reports you'll meet some of the amazing cranes that return here year after year.

Tom Stehn
Aransas National Wildlife Refuge
Austwell, Texas

 


 

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