Fourth Aerial Census of the 2010-11 Whooping Crane Season

Feb 17, 2011 | Aransas National Wildlife Refuge by Tom Stehn | Related Press

The fourth aerial census of the 2010-11 whooping crane season was conducted February 11, 2011 in a Cessna 210 piloted by Gary Ritchey of Air Transit Solutions, Castroville, Texas with USFWS observers Tom Stehn and Brad Strobel.  Flight conditions and visibility were excellent throughout the 6-hour flight.

Sighted on the flight were 238 adults and 42 juveniles = 280 total whooping cranes.  With the addition of a confirmed report on February 8th of a single whooping crane in north Texas east of Dallas in Jones County, the flock size is estimated at 281.  This breaks the previous high of 270 reached in the fall, 2008.  The flock of 281 consists of 236 white-plumaged and 45 juveniles = 281 total.

Cranes observed:

Adults + Young
San Jose 49 + 10  =    59
Refuge 88 + 12  =  100
Lamar 11 +   4  =    15
Matagorda 61 + 10  =    71
Welder Flats 29 +   6  =    35*
Total 238 + 42**= 280

* All-time high for Welder Flats, breaking previous high of 32 set in December, 2010.

** Although only 42 chicks were observed, an estimated 3 others may not have been identified due to their whiter plumage this time of the winter, or else were not picked out in large groups on prescribed burns.

Crane habitat use observed on the census flight (n=280):

111 of the cranes observed were in salt marsh habitat

71 were on prescribed burns

73 were in shallow open bay habitat

22 were on uplands areas

3 were at a game feeder

0 were at fresh water sources

The 73 whooping cranes in shallow bay habitat and the 65 cranes on prescribed burns were both notable. The prescribed burns have changed the distribution of cranes on the winter range, with many cranes moving to the 2 refuge burns from different parts of the wintering area.

Burn Location Unit Number # of Cranes Observed

Matagorda Island        G1                              6

Aransas Refuge          C4/C5                       12

Aransas Refuge          C8/C9                       53

The low tides present on today’s flight contributed to the amount of open bay use observed.  Much of San Jose Island consisted of dry mudflats.  This is normally a tougher time of the winter for whooping cranes to find adequate food resources, and this winter is no exception as evidenced by increased use of uplands, burns, and open bay habitat during the flight.  However, observations continue of cranes catching a few blue crabs.

Tom Stehn, Aransas National Wildlife Refuge

Read the entire article »