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Tom Stehn's Report: Something Special to "Whoop" About!
Feb. 29, 2008
Meet Tom Stehn
Whooping Crane Coordinator, U.S. Fish and Wildlife Service

As you read Tom's report this week . . .
  1. Underline words and phrases that give you clues about the care Tom takes as a scientist.
  2. What are challenges in counting all the cranes?
  3. How many cranes were at Aransas NWR when Tom first counted them in 1982? How many are there today?

Dear Journey North,
On December 4, 2007, I was a part of history. During an aerial count of the whooping cranes, Biologist Darrin Welchert and I, along with Pilot Gary Ritchey, accounted for a record 266 whooping cranes at Aransas!

How did I feel when I realized there was a record number of whooping cranes? At first, I remained aloof as a scientist, double checking my figures and making sure I had not made any mistakes. In my case, this work took place after dinner at a pizza parlor and then spreading all my aerial photos and flight notes out on my kitchen table. After checking my list of territories, comparing the crane pattern seen on the flight compared with the previous week’s pattern, and making sure I had all the crane numbers on each of my seven photos added up correctly, by now it was about 10 PM and I think all I had energy left for was a satisfied “By golly, the cranes have set another record”. Remember: Back in 1941, biologists could find only 15 whooping cranes at Aransas. What a satisfying feeling to be a part of this whole effort to try to save the species.

How many whoopers can you find in Tom's aerial photo? Click to see Tom's answer.

I frequently get asked: “How are you able to count all those cranes and make sure you are not counting the same birds twice?” My answer is always the same. With a big smile on my face, I say “It takes talent.” Well, true, it does take some talent, but I think much more important is that it takes a lot of effort and a whole lot of experience.

Finding every whooping crane is quite a challenge with thousands of other white birds in the marsh (including pelicans and egrets) that make spotting of cranes more difficult. (Try it yourself in the photo.) It takes about seven hours of flying to cover 56,000 acres of marsh to find all the cranes. I drink lots of coffee to stay alert during the long flight. The marsh is divided up into grids and we usually fly transects that are 4 miles long by 0.25 miles wide. I plot the location of every crane I see to make sure I’m not counting the same birds twice. The short transects help reduce the problem of cranes that may fly a short distance and be counted twice. If we see cranes that we think may have moved during the flight, we double back to see if the cranes we had counted already are still present. We stay on course with the aid of a GPS unit that shows our flight path. We make sure our grid completely covers one section of marsh before we move on to search the next area.

Whooping cranes are territorial and every winter I find the same pair of cranes in the same exact part of the marsh. I have a checklist written in the margins of the aerial photos I carry and I check off the cranes within every territory. When they arrive at Aransas in the fall, it is for me like attending a reunion and saying hello again to old friends.

During the record flight on December 4th, we only spotted 260 whooping cranes. However, 2 additional whooping cranes were known to be using agricultural fields nearby in areas we didn’t fly over that day, and 4 whooping cranes were still in migration (1 in west Texas, 2 in Kansas, and 1 still in Canada). The addition of these 6 whooping cranes brought the estimated size of the flock to 266, the most anyone has ever counted at Aransas. I did my first count at Aransas in fall, 1982, with only 73 whooping cranes present that winter. Given the high number of cranes and the bountiful food supply, this winter has been one of the best winters I can ever remember for the whooping crane population. Yes, it was only a piece of history we made that day, but I sure hope to find another record number this coming fall!

Tom Stehn
Aransas National Wildlife Refuge

 


 

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