Third Aerial Census of 2010-11 Season

The third aerial census of the 2010-11 whooping crane season was conducted January 19, 2011 in a Cessna 210 piloted by Gary Ritchey of Air Transit Solutions, Castroville, Texas with USFWS observer Tom Stehn.

The flight only covered 2/3’s of the crane area due to limited flight time.  Flight conditions and visibility were good throughout the 4-hour flight, although clouds made it a harder to find cranes during mid-portions of the census.  A follow-up flight the next day had to be cancelled due to fog and low ceilings.   

Sighted on the flight were 175 adults and 36 juveniles = 211 total whooping cranes.  The only recent confirmed report I have of whooping cranes not at Aransas was one white-plumaged whooping crane in north Texas near Electra on January 2nd.

   Adults + Young
San Jose   51 +   8 =  59
Refuge   80 + 18 =  98
Lamar     9 +   4 =  13
South ½ MI   35 +   6 =  41
Welder Flats   Not flown
Total 175 + 36 = 211


Assuming numbers had remained the same from the previous flight in the areas not covered, the numbers represent an increase of 3 cranes above the previous record-tying count of 270.  However, although I fully expect flock size to be more than the 270 previously tallied, it will take several more flights before I can establish a better estimate of flock size.

Crane habitat use observed on the census flight (n=211):

              74 of the cranes observed were in salt marsh habitat

              82 were on prescribed burns

              21 were in shallow open bay habitat

              31 were on uplands areas

                3 were at fresh water sources

The 82 whooping cranes on prescribed burns was notably very high.

Burn Location     Unit Number        # of Cranes Observed

San Jose Island            –                                3

Matagorda Island         G1                            6

Aransas Refuge          C4/C5                       21

Aransas Refuge          C8/C9                       52

The prescribed burns have changed the distribution of cranes on the winter range, with many cranes moving to the two refuge burns from different parts of the wintering area.  For example, two of the radioed cranes have left Lamar and are staying on the refuge burns and adjacent salt marsh.  One adult female crane was captured on Lamar and radioed on January 8th by biologists organized by The Crane Trust, Wood River, Nebraska.  They set out a snare attached to a long twine, and when the bird stepped in the snare, they yanked on a fishing pole and tightened the snare, ran out from blinds and grabbed the bird.

This is normally a tougher time 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.  A crab count conducted January 7th had found only 6 blue crabs in an hour of walking the marsh, but compared to some winters, this was not too bad.  No wolfberry fruits or flowers had been found, with the crop over for the year.

Salinities are currently 19 ppt in San Antonio bay just north of the refuge.  Several inches of rain that fell

January 15-16th has provided additional drinking water for the cranes in various areas of standing water next to the salt marsh and eased access to drinking water for the cranes.

A severe hail storm that crossed the Texas coast in the early morning hours of January 9th apparently killed over 1,000 birds in a narrow area on San Jose Island stretching over 15 miles.  Initially reported by a waterfowl hunter, a reconnaissance by Texas Parks and Wildlife Department estimated at least 1,000 birds had been killed.  Species found dead included sandhill crane, white pelican, roseate spoonbill, black skimmer, ducks, plovers, and terns.  Sixteen specimens were necropsied by the National Wildlife Health Center, but I do not yet have the results.  During the reconnaissance, TPWD had observed 8 whooping cranes that looked fine.  Additional searches in other parts of the crane range had not find any dead birds.  On today’s census flight, there was no evidence of hail-killed birds or missing whooping cranes on San Jose Island.  I think the whooping cranes dodged nature’s bullet, though we’ll probably never know for sure if a few whooping cranes perished.  Tornados and wind gusts > 60 mph associated with the storm had also damaged buildings in various locations in the Coastal Bend.

       Tom Stehn, Aransas National Wildlife Refuge