March 7, 2013

Whooping Crane Update

Wintering Whooping Crane Update, March 7, 2013
Wade Harrell, U.S. Whooping Crane Recovery Coordinator

A Dallas hunter entered a plea of guilty and was sentenced for killing a juvenile whooping crane. After contacting Texas Parks and Wildlife, the hunter told state game wardens he thought the whooping crane was a sandhill crane. Read the full news release here.

Whooping Cranes on the Aransas National Wildlife Refuge: 

  • We have preliminary lab results on the whooping crane carcass that refuge staff recovered on Feb. 7, 2013. Unfortunately, no conclusive cause of death could be determined given the advanced decomposition and scavenging of the carcass. Bacterial tests of bone marrow did not indicate an infection that would have led to death. West Nile virus testing is still underway. 
  • It appears that some whooping cranes have started to migrate back north, which is several weeks earlier than normal. Perhaps this is not surprising given the unusually warm and dry winter that the southern plains have experienced.  
  • The annual whooping crane festival hosted by the Port Aransas Chamber of Commerce was a success. Tour boats reported seeing a high of 49 whooping cranes along the shoreline of the intracoastal waterway on the Blackjack Unit of Aransas National Wildlife Refuge. Talks and tours were well attended and the weather was cooperative for the most part.
From Texas Whooper Watch and other observers:
  • February 8: Bird watchers at Quivira National Wildlife Refuge in Kansas reported six whooping cranes on the refuge. Staff was not able to reconfirm the sighting however this record is 11 days earlier than any previous refuge migration record dating back to 1960. Prior to this, the earliest record was February 19, 2000. 
  • February 10: Five whooping cranes were reported in Wharton County, north of El Campo. This group has been sighted regularly on private lands in this area throughout the winter.
  • February 17: A confirmed pair of whooping cranes was documented in Matagorda County on The Nature Conservancy’s Mad Island Marsh preserve. Whooping cranes have used this area in previous years but this is the first winter that birds have been documented throughout the winter season.  
  • February 18: Ten whooping cranes were spotted at Granger Lake on the lake shoreline across from Friendship Park. This group consisted of two family groups with one juvenile each and four birds associating as pairs. * See the update below on the marked family group. 
  • February 22: 
    • Texas Whooper Watch received a report of four whooping cranes migrating with about 300 Sandhill cranes west of Vernon, TX.
    • Salt Plains National Wildlife Refuge in Oklahoma received a report of six whooping cranes near Kremlin, OK and 2 whooping cranes near Ringwood, OK.  
  • February 24: The marked family group (two adults and one juvenile) from Granger Lake left arriving in North Texas that evening. They stayed through Feb. 28 and then moved to SW Oklahoma where they remained through March 2. They then moved on to Quivira National Wildlife Refuge in South Central KS, a traditional migration stopover site for whooping cranes, where they currently remain. 
  • March 3: Bird watchers reported eight whooping cranes near North Platte, Nebraska. We are working to confirm this report.

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 Cranes

The 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.

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.