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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 20, 2007 of the Aransas National Wildlife Refuge and surrounding areas.  The total number of whooping cranes located was 253. The estimated size of the flock remains at a record 266.  The flock consists of an estimated 142 adults, 85 subadults, and 39 juveniles.

 

Recap of cranes found at Aransas (253) on the December 20th flight:

 

 

Adults + young

Refuge

  63 + 10

Lamar

   5 +   1

San Jose

  55 +  7

Matagorda

  72 + 12

Welder Flats

  21 +   7

Total

216 + 37 = 253

 

The whooping crane survey was conducted in a Cessna 210 piloted by Gary Ritchey of Air Logistic Solutions of San Antonio, Texas with observer Tom Stehn.  The flight was delayed by early morning fog, but viewing conditions became ideal with clear skies and moderate winds as a front pushed across the coast. Transects were lined out so that flying towards the late afternoon sun was not an issue except for some low light conditions approaching sunset.  Smoke from one refuge burn and two prescribed burns on private lands made for occasionally slightly hazy conditions over small portions of the refuge and San Jose Island.

 

Eight birds were believed overlooked on today’s flight (E. Spalding Cove family, Grass Island pair, 3 subadults).  I estimate that about 98% of the flock has completed the migration with at least 4 whooping cranes still in the Flyway.  One additional whooping crane is presumably with sandhills using agricultural lands just north of the wintering area, last sighted on the Whitmire Unit of Aransas NWR near Indianola on December 6.  The 4 cranes known to still be in migration include one juvenile last reported at Muleshoe NWR in west Texas on November 28, one subadult still in North Dakota, and two whooping cranes reported Dec. 19th about 50 miles up the Texas coast by Big Boggy NWR   Presumably these same 2 cranes had stayed at Cheyenne Bottoms SWA in central Kansas Nov. 8 - Dec. 8, were at Hagerman NWR north of Dallas, Texas on Dec. 17th and departed the following day, and were then reported in flight over Lake Austin near the Big Boggy NWR on Dec. 19th.

 

No whooping cranes are believed to have completed the migration since the last flight on December 4th.  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 also 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 flight, tides were the lowest so far of the winter with large mudflats exposed on San Jose Island.  Seven cranes were noted in open bay habitat.  Two cranes were found on prescribed burn C4 done at Aransas in late November.  No cranes were found at fresh water sources or unburned uplands.  Multiple cranes were seen in high salt marsh habitat presumably foraging on wolfberry.  Low numbers of sandhill cranes were also found in similar areas, also an indication of wolfberries.  These berries are still available to the cranes though presumably past peak abundance.  A crab count done December 11th indicated blue crabs were still available in the marsh.  The cranes have also been finding fiddler crabs to eat as temperatures in December have remained unusually warm.

 

A family group of 1 adult + 1 chick closely associated with a second adult last week south of Pringle Lake on Matagorda Island was this week in a similar location but grouped as 1+1.  I guess the “relationship” observed last week did not work out.

 

Four 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, a pair by Paul’s Mott on San Jose, and a new family on the north end of Big Brundrett Lake on Matagorda Island.  Pairs present last winter but with territories currently unoccupied include Behind Middle Pond and North Power Lake.

 

The next census flight will take place in the first half of January, 2008.

 

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.