by: Chester McConnell, Whooping Crane Conservation Association
It appears that we may never know if the Aransas – Wood Buffalo population of whooping cranes reached the hoped for 300 birds during 2011 – 2012. The weather has been a large factor. First, an unknown number of whoopers cranes did not arrive at Aransas National Wildlife Refuge. Then some traveled around in Texas counties near Aransas Refuge while others spent the winter in Kansas and Nebraska. And weather had a crippling effect on attempts to count the whoopers that did winter on Aransas Refuge.
According to Aransas personnel, “High winds and low cloud cover impeded the census flights scheduled during late February, allowing for only two of the three scheduled census flights. Those flights were conducted on February 25 and 26, 2012. Peliminary data analyses indicated the population of cranes within the surveyed area was 196. Although lower than the previous 245 estimate, the difference is not statistically significant and most likely the result of limited flying time. Also, this number does not reflect whooping cranes outside the survey area, including those that have dispersed.
Radio-marked birds and sightings of whooping cranes from the flyway indicate the birds have begun their northern migration back to Wood Buffalo National Park in the Northwest Territories of Canada where they nest exclusively. Some biologist believe that this earlier than usual northern migration is also due to the unseasonal warm weather. Depending on the weather, biologists hope to conduct another census flight before the end of the month.
Refuge officials also issued an update on the status of whooping cranes that died during the past several months. A report from the first whooper carcass (recovered Dec. 7, 2011) was issued from the National Wildlife Health Center (NWHC) and it indicates the bird had a systemic blood infection. This type of systemic infection has been known to cause death. The refuge is still waiting on the final report from the second carcass (recovered January 18, 2012). A third carcass of a radio-collared bird was recovered (Feb. 29, 2012) and sent to the NWHC in Madison, WI last week for necropsy.
Some good weather news relating to the whoopers is that, as of March 14, the monthly precipitation totals for Aransas National Wildlife Refuge are .85 inches and salinity levels in San Antonio Bay are recorded as 19.7 parts per thousand. With salinity levels below 20 parts per thousand, conditions in the marsh are normalizing and food production for the birds improving. Even so, the refuge is still not to pre-drought conditions and biologists remain concerned.
Since the last Aransas Refuge update, the refuge conducted an additional prescribed burn, raising the winter’s total to 12,310 acres of habitat. The refuge’s fire program hopes to conduct a final burn in the next few weeks on Matagorda Island but the changing weather makes it uncertain. Despite one burn remaining, all of the burns planned in areas whooping cranes would likely use have been completed and were successful.