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 21 December, 2005 of the Aransas National Wildlife Refuge and surrounding areas estimated the number of whooping cranes present at Aransas as 187 adults + 29 young = 216 total. One additional whooping crane is in extreme South Texas in Hidalgo County near Hargill brings the current estimated flock size to 217. This is believed to be the 2004 juvenile that had separated from its parents last fall and had spent the 2004-05 winter with sandhills near Bay City, Texas north of Aransas. One adult and one juvenile have died this fall at Aransas, accounting for a peak population of 189 + 30 = 219. In additional, two reports from good birders were received on December 21 of whooping crane pairs in flight near El Campo and west of Blessing, Texas, both locations north of Aransas by about 30 miles. If these reports can be confirmed, and presuming they were of different pairs based on the distance between reported sightings, the peak flock size for the winter may reach 193 + 30 = 223. Last winter's peak population was a record 217. On December 14, three whooping cranes in flight were reported by birders between Green and Mission lakes on the Guadalupe Delta Wildlife Management Area located about 15 miles north of Aransas. Thus, although I think the flock has completed the migration, there may be a handful of whooping cranes currently with sandhills north of Aransas in south Texas.
Recap of cranes observed on the flight: (216)
adults + young
Refuge 60 + 10
Lamar 4 + 0*
San Jose 40 + 4
Matagorda 67 + 11**
Welder Flats 16 + 4
Total 187 + 29 = 216
* The movement of the Long Reef family from San Jose to Lamar put 7 cranes on Lamar.
** Sets the all-time record for whooping cranes on Matagorda Island by one crane.
Remarks: Good to excellent viewing conditions were present throughout the day with scattered clouds present for only part of the morning. All of the crane winter area except for Burgentine Lake was flown in an 8.0-hour census. An additional area searched was marshlands north of Hynes Bay near Tivoli.
With very good viewing conditions, uncertainty about the numbers of cranes present was caused primarily by crane movements. Uncertainties included 2 cranes on San Jose in the Fenceline territory that moved during the transects and could not be re-located, and 2 cranes on the refuge seen in flight soaring above the census aircraft. In addition, although the number of cranes at Welder Flats remained the same as last week, the distribution of cranes made it possible that the Dewberry Island pair was overlooked. I included 4 of these 6 uncertainties into the flock total and will try to confirm totals sighted on the next census flight. On any given census flight, there are always movements that create uncertainty, and only by doing multiple census flights can an accurate flock total be derived. On today's flight, the banded family group seen on its Long Reef territory on San Jose Island at 0810 hours had flown across Aransas Bay and was found on the Lamar peninsula south of Holiday Beach at 1130 hours. Major movements such as this can really hurt the accuracy of a census count, but in this instance, reading the bands on the family allowed me to document the movement and prevent duplication on the count.
The big surprise of today's flight was the apparent recent arrival of a new single unbanded adult with a juvenile. This 1+1 grouping was sighted on Bludworth Island across from the Lobstick territory. Nearby were 2 subadult cranes. Two additional subadults flew in, forming a group of 4. The 4 walked towards the 1+1, with the lead bird in the 4 in definite threat postures. Later on in the flight, the grouping of 1+1 had moved and was located close to the north end of Dunham Bay. Reports from a tour boat on December 22 placed this 1+1 group in Sundown Bay just north of the Pump Canal. The other group of 1+1 containing a banded adult female has remained on her territory at N. Pipeline Flats. The 1+1 group added to the 214 cranes estimated present at Aransas last week gives a total of 216 at Aransas, the number seen on today's flight.
Interesting locations on today's flight included a single visible from the refuge's observation tower at Mustang Lake, an indication that the resident territorial pair has either not arrived or is wintering elsewhere in the crane area. The family group that in the fall roamed around the north end of San Jose Island was for the second straight week located on the refuge, this week in South Sundown Bay. The Middle Sundown Bay pair was apparently located in the empty territory to their north situated north of the Pump Canal.
Interesting observations of habitat use on today's flight included 8 cranes on a prescribed burn conducted at the refuge's Dunham Bay on December 15th, 13 cranes at freshwater sources, and 6 cranes on gravel roads. Six cranes were in open bay habitat, all at Welder Flats. Fourteen additional cranes were on different kinds of upland habitat, including 2 at a game feeder on Lamar, 3 in feral hog rootings on Matagorda Island, 3 in upland prairie, 3 in oak brush habitat at Welder Flats, and 3 on dry sandflats. The amount of upland use including use of a prescribed burn was a notable difference from last week's flight. This change in type of habitat being used by the cranes is an indication that the main food sources (crabs and wolfberries) are diminished and the cranes are having to scramble to find other food items. This type of change in habitat use is normally seen in most winters in late December through mid-February. The relatively high salinities may also be promoting cranes to use upland areas as some cranes fly to uplands to get fresh water to drink. Tides levels were somewhat higher than last week, measured at 2.7 mlt on December 19. Limited areas of mudflats on San Jose Island were exposed.
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