Whooping Cranes on the Aransas National Wildlife Refuge:
Can You Find the Whooping Cranes?Every winter when the whooping cranes arrive on the Texas coast, biologists fly aerial surveys to try and get an estimate of the endangered birds’ population. These flights are conducted in December when most of the whooping cranes are known to be on their wintering grounds. This is also a prime time for many other birds to be feeding in the marsh. When flying over whooping crane habitat, this is what biologists see. How many whooping cranes do you see? Click Here.
Tracking the Whooping CranesThe Whooping Crane Tracking Partnership recently issued their biannual report. The following is a summary of the data captured from the 2012 breeding season through fall migration (approximately May through November). During the 2012-2013 season, the Whooping Crane Tracking Partnership gathered location data from 36 transmitters during the breeding season and data from 30 transmitters during fall migration. Prior to migration, six transmitters stopped providing data. With the help of the technology, the mortalities of two juveniles and two subadults were confirmed on the breeding grounds of Wood Buffalo National Park. The two other transmitters were confirmed to have broken antenna. The tracking technology also revealed that three cranes spent the summer months in south-central Saskatechewan and 29 marked birds completed the fall migration. The birds began their fall migration on September 7, 2012, and data indicates that all of the birds arrived on the Texas coast by November 27, 2012. It took the cranes an average of 46 days to make the migration with the migration time ranging from 21 to 67 days. The data shows whooping cranes used 261 different locations where they stopped and stayed for more than one night. Stopover locations occurred in every state and province in the Great Plains. Cranes spent the most time at staging sites in Saskatchewan and the Dakotas. The general migration corridor used was similar to past migrations and there were no mortalities detected during the migration.The GPS tracking devices are programmed to record four locations daily and provide both daytime and nighttime locations. Transmitters upload data approximately every 2.5 days allowing for monitoring survival. The technology allows biologists to learn which habitats are being used and where the birds stop during their migration – important information when prioritizing management decisions. Precipitation/Salinity:The refuge has not had any significant rainfall since February 7, when 1.66 inches were recorded. This extended dry period has continued to impact freshwater availability and salinity levels within whooping crane habitat on and around the Aransas Refuge. Over the past month, the salinity levels in San Antonio Bay have ranged between 21 and 30 ppt, well above optimal levels. Weather forecasts for this upcoming weekend include a chance for a significant rain event.Food Abundance: Refuge staff was able to complete a 541-acre prescribed burn last Wednesday along the east shoreline of the Blackjack peninsula, an important foraging area for whooping cranes. This brings the winter burn total to 8,770 acres. This will likely be our last prescribed burn for the winter. The refuge has secured a contractor to rework two freshwater wells on Matagorda Island in order to enhance freshwater resources available to whooping cranes. We expect that work to begin very soon.
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The Matagorda Island Unit of the Aransas National Wildlife Refuge is part of long chain of barrier islands that extend down the Texas coastline. This rugged landscape is host or home to many amazing wildlife species, including whooping cranes, Kemp's Ridley sea turtles, reddish egrets, alligators and coyotes.