Food Supply Low at Aransas but Whoopers Coping

The fifth aerial census of the 2009-10 whooping crane season was conducted January 21, 2010 in a Cessna 210 piloted by Gary Ritchey of Air Transit Solutions of Castroville, Texas with USFWS observer Tom Stehn. Sighted on the flight were 235 adults and 18 juveniles = 253 total whooping cranes. This was 10 birds less than the last flight conducted 1-05-10. However, flight time was limited by fog that did not burn off until 10:30 AM, so some cranes were presumably overlooked, as search time had to be condensed. More telling than the total number of cranes tallied was the distribution observed that seemed to confirm the estimated flock size. However, it definitely appears that one juvenile has died since arriving at Aransas. This juvenile had been found in the refuge’s South Sundown Island territory. On today’s flight, a pair believed to be the S. Sundown Island pair was seen very close to their territorial neighbors to the south. It seemed clear that I was looking at adjacent territorial pairs, and that the S. Sundown Island pair was missing its chick. It is also possible that the Dewberry Island pair at Welder’s Flats has lost their chick, but it is also possible they had moved over to the refuge’s Power Lake on Matagorda Island where there was an unexpected family.

The territories of adult cranes remain difficult to figure out as many of the crane pairs have left their marsh and are searching for food on the uplands. On today’s flight, an unusually high 52 cranes were on unburned uplands, 4 were on the C14 refuge burn, 13 were in open bays, two were at a game feeder south of the Big Tree on Lamar, and 182 (72%) were in salt marsh. Blue crabs are at extremely low levels and the cranes are having to look for other sources of food. This is a very stressful time of winter for the whooping cranes. One additional juvenile that apparently separated from its parents during migration was sighted near Medford, Oklahoma December 14-25 has not been re-sighted but is presumably doing okay in an unknown location.
The flock size is currently estimated at 244 adults + 19 juveniles = 263.

January 21st – Recap of whooping cranes (253) found at Aransas:

* The presence of one chick last seen in Oklahoma makes the current estimated flock size 263, including 19 chicks. One chick has died since arriving at Aransas.

One whooping crane was sighted on 1/17/10 by a TPWD biologist on the Smith Marsh in Matagorda County. The Smith Marsh is private property just to the west of the Nature Conservancy’s Mad Island Marsh Preserve a considerable ways up the coast from Aransas.

Flight Conditions: Visibility was excellent throughout the flight, though the sun angle on late afternoon transects made for difficult viewing conditions when heading into the sun. Winds were light and flight conditions were smooth, enabling us to travel at approximately 130 knots for most of the flight. Due to reported crane movements, the search area was expanded much further out into upland areas. However, only three additional cranes were found in the uplands at Welder Flats, whereas 12 had been located there the previous week. This difference seemed to account for the 10 fewer cranes found on today’s flight compared to the previous flight. In addition, no cranes were found at the refuge’s Burgentine Lake, whereas seven had been present on the previous flight. The largest group size observed was seven birds seen on the uplands on San Jose and in the marsh on Matagorda Island.
– Tom Stehn, Aransas National Wildlife Refuge