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 01 March, 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 + 26 young = 215 total. One adult and four juveniles have died this winter at Aransas, with an estimated peak flock size of 190 + 30 = 220.
Recap of cranes observed on the flight: (193)
adults + young
Refuge 52 + 5
Lamar 6 + 0
San Jose 28 + 5
Matagorda 65 + 11
Welder Flats 17 + 4
Total 168 + 25 = 193
Remarks: Visibility was excellent throughout the flight with sunny skies and 10-mile visibility. Approximately 4 adult pairs, 1 family, and 11 subadults were believed overlooked. Crane movements to freshwater dugouts and prescribed burns made it more difficult to account for all the cranes.
The N. Pipeline Flats juvenile was not with its single parent (female W-nil) and is believed dead. This juvenile had been seen by itself on several occasions during the past few weeks, a potential indication of illness making it more vulnerable to possible predation. No carcass was found, and I can always hope I simply overlooked the juvenile, although extra searching was done in its territory at the end of the flight. Female W-nil was by itself and has not repaired. The single adult with a juvenile that arrived late in December and then re-paired was not located for the second consecutive flight. This family did not have a defended territory, so if the juvenile has died, I am unable to differentiate this unbanded pair from other duos. I am worried that this may be another instance of juvenile mortality this winter, although perhaps the family has left the census area.
It is always frustrating not to find all of the cranes on a flight, especially when census conditions are excellent. It is always possible to fly directly over cranes in the airplane's blind spot and not see them, or cranes may move and get overlooked. It is also possible that a small number of cranes may have left the winter range for weeks at a time before returning, especially subadult cranes that sometimes move inland with sandhill cranes. However, no one has recently reported cranes away from Aransas. Although a pair of whooping cranes at Aransas was once believed to have started the migration the first week in March, it will typically be 3-4 more weeks before a few whooping cranes will start the migration. It is most likely that I simply overlooked up to 22 cranes on today's flight. On the previous flight done February 15, I had only located 10 cranes at Welder Flats and presumably had overlooked the others. On today's flight, the typical 21 cranes were found on Welder Flats, including the territorial pair and 2 subadults by Dewberry Island. This demonstrates a census count that had come up noticeably short, but the cranes were found on the subsequent flight.
The subadult whooping crane that wintered with sandhills in the Rio Grande valley 30 miles north of Mexico has not been seen since January 12. It is likely that this white-plumaged whooping cranes has started the migration. Quivira NWR in Kansas reported over 4,000 sandhill cranes present yesterday, so the sandhill migration is underway. About 50 sandhill cranes were seen at Aransas on today's flight, down from the numbers seen 2 weeks ago.
Interesting locations on today's flight included the following:
a) The unknown family group first sighted this winter on San Jose has returned to San Jose where it has been located on the Feb. 1, 15, and March 1 flights.
b) Two subadults are now using the Big Tree marsh / Johnson Ranch area on the Lamar Peninsula. One of the two is believed to have been the single wintering by itself in the marsh south of Holiday Beach on Lamar.
c) Bands were looked for on one adult in the Twin Lakes pair that for years has had an aluminum band on its right foot. Despite an excellent look, no band was seen, indicating perhaps that the metal band has finally fallen off. The bird had been banded in 1985.
d) Seventy-six cranes were found on Matagorda Island, just two short of a record total set earlier this winter.
e) Ten cranes were found on the area of Ayres and Roddy islands.
Food resources continue to be considered suboptimal for the whooping cranes. From the habitat use observed on today's flight, I don't believe the cranes are finding many crabs to eat. Many cranes were in unvegetated lakes and tidal flats, areas with limited vegetation for crabs to use as cover. Late-December through mid-February is usually a difficult time for the flock. Tides have risen more than a foot since mid-February, measured at 2.5 mlt on Feb. 28th. However, considerable areas of the marsh including cut-off ponds and extensive mudflats on San Jose Island are dry from lack of rainfall. It is noteworthy that the marshes on Matagorda that are mostly connected with the bays are showing normal water levels, a very different scenario from the rest of the crane area.
Habitat use on today's flight included 21 cranes in open bays (compared to 47 on Feb. 15th when tides were more than a foot lower), 3 on uplands formerly rooted up by feral hogs, 5 standing on dirt roads, 19 on prescribed burns, and 13 near sources of fresh water. The drought in Texas is continuing with rainfall deficits resulting in high marsh and bay 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. Thirteen cranes were utilizing areas burned Feb. 28 on Matagorda Island, a management effort aimed to provide a supplemental food source for the cranes during a difficult period of the winter.
Due to a 9-day closure of state waters to commercial blue crab trapping February 18-26, many active crab traps were removed from interior marshes in the crane area. The Texas Parks and Wildlife Department organizes the pickup of abandoned traps annually and solicits help primarily from sportsmen. Especially notable were about 100 traps no longer in the southern end of the crane range on San Jose Island. These traps may have been removed by the commercial fisherman 1-2 days before the closed season, or else were picked up by members of the general public or State during the closure. State wardens are believed to have picked up about 100 abandoned traps on the edge of the bay along Matagorda Island. The crane area looks much better than it did two weeks ago with fewer of these 'ghost' traps that continue to catch fish and crabs for months even after they are abandoned. Great progress has been made in the last 5 years picking up thousands of abandoned traps. An estimated 200 abandoned traps are still in the crane range, but many of these are old, deteriorated, and embedded in mud and no longer are catching critters.
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: 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/
Patty Waits Beasley
Corpus Christi, TX