The following report is forwarded with permission from Tom Stehn, USFWS biologist and US Whooping Crane Coordinator.
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An aerial census on 22 March, 2006 of the Aransas National Wildlife Refuge and surrounding areas found 143 adults and 20 chicks =163 total.
Recap of cranes observed on the flight: (163)
adults + young
Refuge 45 + 5
Lamar 6 + 0
San Jose 26 + 4
Matagorda 50 + 8
Welder Flats 16 + 3
Total 143 + 20 = 163
Remarks: Finding cranes was difficult throughout the flight because of dark overcast skies. As many as 25 cranes could easily have been overlooked. Crane movements to freshwater dugouts and prescribed burns also made it more difficult to find all the cranes. Nevertheless, the census total was so low that it is estimated that 20-30 whooping cranes may have started the migration, or up to 14% of the flock of 215.
It is still early for the bulk of the whooping cranes to head north. I do have some evidence that the migration has started. One whooping crane was present March 11th 16th on the Platte River in Nebraska. We believe this was the whooping crane that wintered with sandhills in extreme south Texas until around March 3 and thus migrated more on the earlier schedule of the sandhill cranes. No sandhill cranes were seen at Aransas on today's flight, with sandhill numbers already having peaked on the Platte River. A birdwatcher reported seeing 3 whooping cranes northwest of Fort Worth, Texas on March 19th. This is right on the expected migration path of the cranes, and his observations sounded credible. Two whooping cranes were confirmed present on the Platte River on March 24th. With the low number of cranes found on the census flight and knowledge that whooping cranes can leave in late March, it seems likely that some are currently flying north.
Conditions are tough for the whooping cranes at Aransas right now, with few blue crabs to eat and high water salinity forcing them to fly inland to get freshwater to drink. Two days ago, I walked to numerous ponds looking for crane tracks and their droppings. From the material I picked up, I found mostly shells about the size of the fingernail on my smallest finger. Think how many of these tiny shelled critters the whooping cranes would have to eat to get enough calories, and then all the grinding up of these shells their stomachs would have to do to digest all that material to get the small bits of meat.
Habitat use on today's flight included 4 cranes in open bays, 6 standing on shell roads, 7 others on uplands (including 2 on a disked firebreak and 2 using hog rootings), 21 on prescribed burns, and 24 near sources of fresh water. Fifteen of the cranes were on a refuge prescribed burn conducted March 21st. The drought in Texas is continuing with rainfall deficits resulting in high salinities that force the cranes to seek out fresh water to drink. The drought is rated as 'severe' on the coast and as 'extreme' in the Texas Hill Country including San Antonio. Bay salinities at the refuge are 25 parts per thousand. Tides have risen dramatically since February, measured at 2.8 mean low tide on today's flight. The rise in tides is correlated with fewer cranes being found in open bay habitat. On today's flight, only 4 cranes were in open bays, compared to 47 on Feb. 15th when tides were much lower.
On today's flight, the cranes at several locations seemed more 'bunched up', a tendency sometimes observed in early spring before the migration. Six cranes were on the Big Tree Marsh, 11 were on Ayres Island/South Rattlesnake, and 5 cranes were on Long Reef. Several of the cranes looked 'dingy', indicating an ongoing molt of body feathers.
Interesting locations on today's flight included the following:
a) Widowed female W-nil was with two other cranes on a prescribed burn.
b) The Victoria Barge Canal family group was at a windmill pond just east of the Corps of Engineers dredge material site at Swan Point.
c) The Dewberry Island pair was on the uplands of the D H Texas Investments property proposed for development near Port O'Connor.
d) Seismic operations were ongoing next to the North Lamar crane territory with that pair found on the adjacent Big Tree marsh.
Whooping Crane Coordinator
U.S. Fish and Wildlife Service
P.O. Box 100
Austwell, TX 77950
(361) 286-3559 Ext. 221
fax (361) 286-3722
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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.
Anyone wanting to contact Tom about the report or the whooping crane projects can reach him via email at: firstname.lastname@example.org. Other information, including archived copies of these reports, can be found at the Texas Whooping Crane web site at http://www.ccbirding.com/
Patty Waits Beasley
Corpus Christi, TX