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 15 February, 2006 of the Aransas National Wildlife Refuge and surrounding areas estimated the number of whooping cranes present in the Aransas-Wood Buffalo flock at 189 adults + 27 young = 216 total. This total includes one whooping crane in extreme South Texas in Hidalgo County, and one whooping crane last seen east of Pierre, South Dakota on January 3rd. One adult and three juveniles have died this winter at Aransas, accounting for a peak flock size of 190 + 30 = 220.
Recap of cranes observed on the flight: (185)
adults + young
Refuge 55 + 7
Lamar 6 + 0
San Jose 42 + 5
Matagorda 51 + 9
Welder Flats 8 + 2
Total 162 + 23 = 185
Remarks: Visibility was difficult throughout most of the flight due to overcast skies and haze. Two extra landings were made to clean the buildup of haze off the windshield. With these conditions, I anticipated finding only about 90% of the cranes. The results were even less than that, with approximately 86 % of the flock located. Five adult pairs, 4 families, and an estimated 9 subadults were believed overlooked.
Two juveniles were not with their parents and are believed dead. These included the Grass Island juvenile and one of the 'twin' Middle Pond chicks. No carcasses were found and the causes of death unknown. This is the second winter in a row that one juvenile has died in a family that arrived with 'twin' juveniles. Could it be that 4 whooping cranes in a territory can not quite find as much food as 2 or 3 cranes in a territory, leading to problems for one of the juveniles? The juvenile with the widowed single adult N. Pipeline Flats female has split off and was by itself in the territory. The N. Pipeline Flats female W-nil was with an unbanded crane, a preliminary sign of re-pairing.
Interesting locations on today's flight included the following:
a) The single adult family first documented present December 21st apparently has re-paired. They were seen on today's flight as two adults with the juvenile in the bay across from Mustang Slough. They apparently have not carved out a territory.
b) The unknown family group first sighted this winter on San Jose was back on San Jose on the Feb. 1 and Feb 15 flights. After spending November and early December on San Jose, they had moved to the refuge where they were located on several flights from Dec. 14-Jan. 11th. They also apparently do not yet have a winter territory which they defend.
c) A single subadult has started using the Big Tree marsh / Johnson Ranch area on the Lamar Peninsula. It has been seen at a game feeder along with the territorial pair. Today, the single was in Cow Chip Bayou in the same general area. A different single subadult continues to winter by itself in the marsh south of Holiday Beach on Lamar and was found on today's flight standing on a dirt road that leads to a gas well on Newcomb Point.
d) The South Matagorda Island family group with one adult with a red band was seen by a refuge volunteer on refuge burn unit C1 at 0830 am. This family group was not located on the census flight. This family group had apparently left its territory and flown the relatively short distance across Ayres Bay to utilize the refuge burn.
e) The Lobstick family was in a fresh water site inside a Corps of Engineers dredge material area on Bludworth Island.
Food resources continue to be considered suboptimal for the whooping cranes. Late-December through mid-February is usually a difficult time for the flock. Tides are still unusually low, measured at 1.1 mlt on Feb 13th and 1.6 mlt on Feb. 15th. Thus, most of the blue crabs are in the deeper bay waters and unavailable to the cranes. However, one tour boat captain reported seeing the cranes picking fairly large crabs out of the dry mud. The marshes on San Jose Island were particularly dry with large expanses of dry mudflats, the most observed so far this winter. However, the 47 whooping cranes located on San Jose remains at the level present all winter.
A small number of cranes may have left the usual winter range. On Welder Flats, only 10 cranes were located with an estimated 12 not located despite an extensive search, including nearby upland areas and fresh water dugouts. This is an unusual event if indeed that many cranes have moved elsewhere.
Habitat use on today's flight included 47 cranes in open bays, 9 on uplands, 16 on prescribed burns, 6 standing on dirt roads, and 25 near sources of fresh water. This is a very high amount of use of open bay habitat, a result of the low tides having drained large expanses of marsh, particularly on San Jose but noticeable throughout the crane area. The drought in Texas is continuing with rainfall deficits resulting in high salinities in the marshes and bays forcing the cranes to seek out fresh water to drink. Three of the cranes at fresh water were in a confined dredge material disposal area. The upland use included 3 cranes foraging in bare soil turned up by feral hogs within a patch of tall brush on the south portion of Matagorda Island. Eleven cranes were utilizing areas burned last week on Matagorda Island, a management effort aimed to provide a supplemental food source for the cranes during a difficult period of the winter and to keep brush from invading coastal prairie.
Flights from now until the start of the spring migration will be conducted every other week due to budget shortfalls. Fewer flights are normally conducted during that portion of the winter in most years.
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