Sixth Aerial Census of 2010-11

The sixth aerial census of the 2010-11 whooping crane season was conducted March 1, 2011 in
a Cessna 210 piloted by Gary Ritchey of Air Transit Solutions, Castroville, Texas with USFWS
observers Tom Stehn and Brad Strobel. All portions of the crane range were covered in the 6-
hour census. Flight conditions were excellent, though late afternoon sun made it difficult to find
cranes when flying towards the sun.

Sighted on the flight were 216 adults and 41 juveniles = 257 total whooping cranes. The
expanded range of the cranes on upland areas and movements to fresh water made it harder to
find all the cranes. At least five additional family groups and pairs (14 cranes) and 7 subadults
were estimated to have been overlooked.

  Adults + Young
San Jose 48 + 8 = 56
Refuge 80 + 13 = 93
Lamar 17 + 5 = 22
Matagorda 51 + 10 = 61
Welder Flats 20 + 5 = 25
Total 216 + 41 = 257

Observations on today’s flight confirmed the loss of two additional whooping cranes so that
winter mortality in 2010-11 has totaled 4 cranes (3 adults and 1 juvenile). No carcasses have
been found, and cause of the deaths is unknown. On today’s flight, one group of 1 adult with 1
chick was observed on the G1 prescribed burn on Matagorda Island with no other cranes around.
Also, for the third flight in a row, the East Spalding Lake juvenile was not found, with just the
adult pair seen on the territory. With this mortality, the current flock size is estimated at 279.
The peak size of the Aransas flock this winter was 283.

On March 1st, one whooping crane was confirmed present in a flock of > 10,000 sandhills cranes
near Pampa, (north of Abilene) in the Texas Panhandle. It’s likely that what might have been
the same crane seen in January and February in Texas near Electra and Anson never wintered
at Aransas, but instead elected to remain with sandhill cranes in north Texas and has started its
migration north with sandhills.

Crane habitat use observed on the census flight (n=257):
160 of the cranes observed were in salt marsh habitat
40 were in shallow open bay habitat
21 were on prescribed burns
20 were at fresh water sources
9 were on uplands areas
7 were at game feeders

The continuing moderate use of prescribed burns and heavy use of open bay habitat is notable,
although cranes are finding low numbers of blue crabs in the marsh. Low tides are continuing
with over 70% of San Jose Island consisting of dry mudflats. Cranes are continuing to seek out
freshwater to drink because of high marsh salinities.