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April 10, 2013

Whooping Crane Update

 Wade Harrell, U.S. Whooping Crane Recovery Coordinator 


Since whooping crane migration is well underway and we expect that most birds will depart the coast over the next couple weeks, this will be the final Whooping Crane Update for the season. We expect to begin posting Updates once again in early November. The final 2012-13 Annual Whooping Crane Survey will also be made available on this site within the next few months.

Whooping Cranes on the Refuge:
Birds are still being seen on the refuge, including the pair at the observation tower. All the birds from the Lamar area appear to have left. Based on the tracking data and incidental observations, it appears that the birds using the periphery areas of the winter range (i.e. Lamar, Granger Lake, El Campo, Welder Flats) have been the first to depart this year. Though the birds seem to be leaving in mass, they actually have staggered departures and leave in small groups. This is important as it ensures survival of the species. If they were to all leave together and encountered bad weather or some other catastrophic event, it could put the whole flock in jeopardy.

Texas Whooper Watch:
There have not been any sightings of birds reported through Texas Whooper Watch since the last Update. This is predictable. When headed back to Canada, the whooping cranes are in a hurry to get to their nesting grounds. They must get back in time to establish their territory, lay their eggs and give their chick(s) ample time to mature before they return to the Texas coast.

Tracking Efforts:
As of Monday, April 8, 14 of the marked birds that we are actively receiving data on were still present on the coast and 21 have begun migration. Based on this information and other observations, it is likely that greater than 50% of the birds in the Aransas/Wood Buffalo flock are currently migrating north. Of the 21 marked whooping cranes currently in migration, 14 are as far north as Nebraska and the Dakotas. It appears that late-season snowstorms may be slowing migration into Canada.

Food Abundance:
The refuge has completed the winter prescribed burn program, including 8,770 acres treated. The goal was to burn between 7,000 and 10,000 acres. The birds were documented feeding in the burned areas throughout the refuge this season. The use of prescribed burning as a management tool is particularly important during dry winters, providing extra resources when food items in the marsh may not be as abundant.

Precipitation/Salinity:
The refuge received 0.30 inches last Wednesday (April 3). The last significant rain event was on February 5, with most of February and March being extremely dry. Salinity levels in San Antonio Bay have ranged from 13 to 30 ppt. since our last update. We did have a dip in salinities around the first of the month after the bay and coastal marshes received needed freshwater inflows from a rain event in the upper portions of the Guadalupe/San Antonio watershed. Unfortunately, this freshening of the bay was short-lived and the salinity level in San Antonio Bay is currently 28 ppt, higher than the ideal for available freshwater and marsh food resources.

Taking a look into the past as we consider the future:
The following graphic shows the expansion of wintering whooping cranes on and around the Refuge over the past 55 years (1951-2006). As we have seen this winter, this expansion has now moved to a few inland locations such as the Granger lake area. This trend gives us hope that the species will continue on the upward trend. We look forward to continue learning more about the species so we can assist a multitude of partners in moving conservation efforts forward.
 

Last Updated: Apr 15, 2013
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