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The following report is forwarded with permission from Tom Stehn, USFWS biologist and US Whooping Crane Coordinator.
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.
Anyone wanting to contact Tom about the report or the whooping crane projects can reach him via email at: email@example.com. Other information, including archived copies of these reports, can be found at the Texas Whooping Crane web site at http://www.ccbirding.com/
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An aerial census on December 11, 2002 of the Aransas National Wildlife Refuge and surrounding areas estimated the number of whooping cranes present at 164 adults + 15 young = 179 total.
Recap of cranes observed: (179)
adults + young
Refuge 47 + 6
Lamar 6 + 0
San Jose 40 + 2
Matagorda 49 + 6
Welder Flats 22 + 1
Total 164 + 15 = 179
Remarks: Thick overcast skies starting late morning made it difficult to find cranes throughout the afternoon. All of the crane area except for Indianola was covered in 8.0 hours of flight time.
Conclusions from the flight:
A. At least 4 additional subadult cranes were found, bringing the peak winter population to 180, a welcome increase from the peak of 176 present last winter.
B. It is believed that one of the 16 chicks is missing and has died. A family group on the north end of the crane range by Pringle Lake was not located on the last two census flights. Present in that area had been one family group and one pair. The past two flights, only 2 pairs were present. The most logical conclusion is that the chick has died. Thus, 164 adults + 15 juvenile whooping cranes are currently present at Aransas. The peak population for the 2002-02 winter is 164 adults +16 young =180. The all-time high for the Aransas/Wood Buffalo population was 188 in the 1999-2000 winter.
C. A total of 184 whooping cranes were actually observed on today's flight. Five of these may have been duplications (i.e. cranes seen twice in different locations during the flight). A trio of subadults was first observed in flight over the refuge's Dunham Bay and landed nearby. They could have crossed the bay from San Jose Island. Two trios had been present on San Jose an hour earlier. We flew back over to San Jose to see if the two trios were still present, but the trio near Vinson Slough had moved and could not be located. It is unknown if they were the trio that landed by Dunham Bay. Similarly, a duo on the south end of Matagorda Island could have moved a short distance and been counted twice. I take a very conservative approach on duplications. If I suspect a duplication and cannot prove otherwise, I assume it is. Many times on flights, I assume I'm seeing a duplication and upon re-checking, it turns out to be different cranes. Thus, it is likely that between two and five more subadult cranes are present at Aransas. Future flights will try to determine the exact peak population, currently estimated at 180, but which could be as high as 185.
The distribution of cranes was similar to last week lending confidence to the designation of territories and the population estimate. There were no changes in the number of cranes found on the refuge or Welder Flats, and an increase of 2 on Lamar and 2 on San Jose. The peak population of 180 consists of 132 adults, (maximum of 66 pairs or potential pairs), 32 subadults, and 16 chicks. Territorial situations with uncertainty include Jay Bird Point, Tee Bayou, Mustang Lake and Spalding Point.
The bird with a drooping left wing was observed in a duo near the airstrip on Matagorda Island, with the wing not hanging all the way to the ground as was observed 2 weeks ago.
A commercial fishing boat was observed stuck on an oyster bar along the Victoria Barge Canal and the Coast Guard was notified.
Status of migration:
Most or all of the flock has arrived at Aransas. The whooping crane near the northern border of Kansas was last observed on November 30th and could have continued on in migration.
Habitat: Only the marshes on San Jose still had extensive mudflats, with about half of the tidal flats showing exposed mud. The cranes are feeding on wolfberry and crabs, with fewer sandhill cranes still in the salt marsh utilizing wolfberry fruits. Three whooping cranes were on uplands at Welder Flats with sandhill cranes. No cranes were located in open bay habitat on today's flight.
Unusual Locations: Two cranes have been staying consistently in the Mustang Lake marshes and are believed to be the territorial pair present last winter. Surprising locations were the Big Tree pair south of Holiday Beach, a subadult duo north of Holiday Beach, and the Allyn's Bight pair that had moved north to Long Reef. This is at least the second time this winter that pair has been documented off their traditional territory.
- Tom Stehn
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Patty Waits Beasley
Corpus Christi, TX