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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 census was conducted December 04, 2007 of the Aransas National Wildlife Refuge and surrounding areas.  The total number of whooping cranes located was 260.  I estimate that about 98% of the flock has completed the migration with at least 4 whooping cranes still in the Flyway.  Two additional whooping cranes are with sandhills using agricultural lands near Aransas.  The addition of these 6 whooping cranes brings the estimated size of the flock to 266.  The flock consists of an estimated 140 adults, 87 subadults, and 39 juveniles.

 

Recap of cranes found at Aransas (262) and still in the flyway (4).

 

 

adults + young

Refuge

  65 + 10

Lamar

   7 +   1

San Jose

  56 +   8

Matagorda

  73 + 12

Welder Flats

  21 +   7

Agricultural fields

    2  +  0

Flyway

    3  +  1

Total

227 + 39 = 266

  

The whooping crane survey was conducted in a Cessna 210 piloted by Gary Ritchey of Air Logistic Solutions of San Antonio, Texas.  Observers were Tom Stehn and Darrin Welchert.  Viewing conditions were ideal with clear skies and light winds.  Transects were lined out so that flying towards the late afternoon sun was not an issue.  However, smoke from two prescribed burns on private lands made for hazy conditions over San Jose Island the last 2 hours of the flight.  The smaller of the two ongoing burns was on San Jose Island uplands. 

 

A total of 222 adults + 38 chicks = 260 total were found on the census.  Additional whoopers in the flyway are one bird in Saskatchewan sighted Nov. 24, two cranes sighted at Cheyenne Bottoms WMA, Kansas on Dec. 4, and one juvenile crane first sighted with sandhill cranes at Muleshoe NWR in West Texas on Nov. 27.  Additional birds believed present but not located on today’s flight are one crane seen in the farm fields just southwest of Aransas seen most recently on Nov. 29, and one crane seen in the rice country north of Welder Flats on December 3. 

 

No additional whooping cranes are believed to have completed the migration since the last flight on November 27th despite a very weak cold front that reached Aransas on November 30th and a strong cold front that reached Aransas on December 3.  The increase in the flock count since last week was the confirmation of one additional family group present that last week I had treated as a duplication meaning that I thought one family group had moved during the census and had been counted twice.  Today’s flight confirmed that this family was not a duplication and is a new family carving out a new territory.

 

The estimated flock size of 266 is a result of the excellent production of 40 juveniles sighted on the nesting grounds in August.  With 38 juveniles at Aransas and 1 in West Texas, survival of the juveniles since August has been excellent.  One carcass of a juvenile was found this fall in Saskatchewan with an undetermined cause of death.  Adult survival since last spring has been very good.  Mortality of white-plumaged cranes between spring and fall, 2007 is at most 9 birds, or 3.8% of the flock present at Aransas in spring, 2007.  This is calculated by taking the spring flock size (236), adding the number of juveniles that made it to Texas (39), and subtracting the current estimated flock size (266).  In the past two years, mortality between spring and fall has been above average and totaled over 20 birds each year. 

 

On today’s census flight, there could have been crane movements that resulted in a duplicate count involving several birds.  However, the numbers and distribution matched closely the crane distribution on the previous flight so that the flock estimate of 266 is considered solid.

 

On the flight, 11 cranes were found on prescribed burn C4 done at Aransas one week ago.  Tides were the lowest so far of the winter and 8 cranes were noted in open bay habitat.  No cranes were found at fresh water sources or unburned uplands.  Three cranes were found loafing on an oyster reef in St. Charles Bay just off the refuge’s Bird Point.  In 25 years of watching cranes at Aransas, this is the first time that I recall whooping cranes ever standing on an oyster reef.  One crane was on the high part of the reef while the other two were in shallow water on the edges of the reef.  Low numbers of sandhill cranes were found in vegetated saltmarsh habitat, and indication of foraging on wolfberries.  The crop is currently very abundant and near or at the peak of fruiting.

 

A family group of 1 adult + 1 chick found last week south of Pringle Lake on Matagorda Island was this week in a similar location but grouped as 2+1.  This is the first indication that re-pairing of the widowed adult may have occurred.

 

Three new territorial pairs have been noted so far this winter.  They are pairs north of the refuge’s Dunham Bay, on Newcomb Bend south of Holiday Beach, and the new family on the north end of Big Brundrett Lake on Matagorda Island.

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.