Aransas Flight Report 12-02-09

The second aerial census of the 2009-10 whooping crane season was conducted 02 December 2009 in a Cessna 210 piloted by Gary Ritchey of Air Transit Solutions of Castroville, Texas with USFWS observer Tom Stehn. Visibility was very good for most of the flight, but mid-day winds gusting to 25 from the northwest made for a bumpy ride and made the made the task of finding cranes more difficult. Sighted were 191 adults and 17 juveniles = 208 total. This was an increase of 117 cranes since the last flight conducted November 12th. I am expecting up to 22 juveniles based on August fledging surveys done on the nesting grounds by CWS. With that number of juvenile produced, the flock may experience a break-even year with a flock total around 247 expected.

November 12th – Recap of cranes (208) found at Aransas on the aerial:


Migration Update: Cold fronts that reached Aransas on November 16, 20, 24, and 30 helped the cranes complete their 2,400-mile long migration that had begun 2 months ago for some birds.
Additional cranes are known still in migration in KS, OK, and TX, although numbers are much lower than the big wave of cranes that moved through OK and KS in mid-November. Three other whooping cranes are presently near the coast. On December 1st, one whooping crane was confirmed in a flock of sandhills near Collegeport, about 50 miles northeast of Aransas. Two cranes have been staying north of Tivoli about 15 miles north of Aransas. The addition of these 3 cranes brings the estimated total on the coast to 211.

Crane Identities: The Mustang Lake pair of cranes visible from the refuge observation tower arrived approximately November 24th.

Habitat Use: Tides measured at the refuge boat ramp were high (2.5 feet). The marshes on San Jose Island were notably flooded with large expanses of open water. Salinities dropped noticeably in November so that the cranes are drinking directly from the marsh and have stopped making flights to fresh water dugouts. Salinities on 12/02 were measured at 15 parts per thousand (ppt) at the refuge boast ramp and at 5 ppt in the adjacent marsh. The refuge received 7.8 inches of rain in November as El Nino ended the drought. The largest rain received was 4.35 inches on November 20th. Other areas including Rockport and Lamar got between 12 and 16 inches of rain during that same storm event.

The cranes have responded to the flooded conditions with 33 cranes seen on uplands during today’s flight. I’ve seen this before when cranes utilized freshly flooded uplands with Aransas having received additional rain December 1st. Two cranes were near an upland crane feeder on the Lamar Peninsula. No cranes were in open bay habitat, and there are currently no prescribed burns in the crane area. The largest group size observed was 7 birds seen on in salt marsh on the south end of Matagorda Island. Numerous photographs were taken to document the spread of black mangrove into the crane area.
– Tom Stehn, Aransas National Wildlife Refuge