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Greetings all!

The following report is forwarded with permission from Tom Stehn, USFWS biologist and US Whooping Crane Coordinator.

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An aerial whooping crane census was conducted March 4-5, 2008 at the Aransas National Wildlife Refuge and surrounding areas.  The estimated size of the flock remains a record 266.  The flock consists of an estimated 144 adults, 83 subadults, and 39 juveniles.

 

The total number of whooping cranes located on the census was actually 268, with presumably at least 3 cranes that moved and were counted twice.  With the flight conducted on two consecutive afternoons, it would be expected that a few cranes could move between portions of the census area and be counted on both days.

    

Recap of cranes found at Aransas (268):

 

 

 

Adults + young

Refuge

  61 + 10

Lamar

    4 +   1

San Jose

  69 +   8**

Matagorda

  75 + 12**

Welder Flats

  21 +   7

Total

230 + 38 = 268

 

               **  Record number.

 

The whooping crane survey was conducted in a Cessna 210 piloted by Gary Ritchey of Air Logistic Solutions of San Antonio, Texas with USFWS observer Tom Stehn.  The flight was conducted over two afternoons due to other contract commitments of the aircraft.  Census conditions were ideal both days with full sunshine and moderate winds.  We seemed to struggle on the first afternoon’s flight, with 4 known territorial pairs or families overlooked.  Finding cranes seemed much easier the following day.  At the end of the flight on the second day, we returned to territories where cranes had been overlooked the previous day and found all the “missing” birds (n=11).

 

I estimate that all the whooping cranes are still at Aransas except for 1 juvenile presumably wintering with sandhills someplace in West Texas that was lasted sighted at Muleshoe NWR Nov. 27-28, 2007.  Other than for a few birds, it is usually the last week in March when some of the cranes start the migration.  The majority of whooping cranes remain at Aransas into April.  They “know from experience” that conditions are still frozen up north.

 

There is no evidence of any whooping crane mortality having occurred this winter.  The Lobstick male that had difficulty flying earlier in the winter has apparently recovered fully.  This crane banded as a juvenile in 1978 is approaching 30 years of age and is the oldest known-aged bird in the flock.  However, one of its two chicks may be ill since the chick has been observed sitting down on several occasions, a behavior that can indicate illness.  Healthy cranes rest standing up.

 

On the flight, crane locations indicated a shift in habitat use.  Eleven cranes were on prescribed burns, 4 were in uplands, and 10 were at or next to fresh water sources.  Bay salinities were measured at 20 parts per thousand on March 6, a level at which some cranes will start seeking out fresh water to drink.  The upland use observed (4 cranes) consisted of 3 cranes at a wild game feeder and 1 crane on a disked firebreak.  A notable 47 cranes (17.7% of the flock) were in open bay habitat, presumably foraging on clams and other invertebrates.  However, blue crabs can occasionally be encountered in open bay habitat, and cranes have recently been observed still finding large blue crabs to eat.  Tides were low, with the tops of oyster reefs in the bays exposed. The Mustang Lake family group was quite close to the refuge observation tower providing good views for the refuge visitors.

 

A total of 654 abandoned crab traps were picked up in Aransas and San Antonio Bays by 38 people in 14 boats during the coast-wide closure Feb. 15-24, 2008.  Trap pickup in those 2 bays accounted for 50 % of the coastal total of 1,300 traps retrieved.  These traps abandoned by commercial crabbers continue to catch fish and crabs and the occasional turtle if they are not removed from the water.

  

The next census flight will take place sometime in early April.

 

Tom Stehn, Whooping Crane Coordinator
U.S. Fish and Wildlife Service
Aransas NWR
P.O. Box 100
Austwell, TX 77950
(361) 286-3559 Ext. 221
fax (361) 286-3722
E:mail: tom_stehn@fws.gov

 

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Where applicable, CWS stands for Canadian Wildlife Service; USFWS is US Fish and Wildlife Service. Crane monitoring involves cooperative efforts and support by both countries, plus many volunteers and non-profit organizations along the way.