LITTLE ROCK - (AGFC) Preliminary findings from the U.S. Geological Survey's National Wildlife Health Center showed that blackbirds in Arkansas died from impact trauma. These findings are consistent with the Arkansas Game and Fish Commission's statement.
The AGFC concluded that such trauma was probably a result of the birds in Beebe being startled by loud noises on the night of Dec. 31. The startled birds flew into objects such as houses or trees. Scientists at the USGS NWHC performed necropsies - the animal version of an autopsy - on the birds and found internal hemorrhaging, while the pesticide tests they conducted were negative. Results from further laboratory tests are expected to be completed in two to three weeks.
"Although wildlife die-offs always pose a concern, they are not all that unusual," said Jonathan Sleeman, director of the USGS NWHC in Madison, Wis. "It's important to study and understand what happened in order to determine if we can prevent mortality events from happening again."
In 2010, the USGS NWHC documented eight die-off events of 1,000 or more birds. The causes: starvation, avian cholera, Newcastle disease and parasites, according to Sleeman. Such records show that, while the causes of death may vary, events like the red-winged blackbird die-off in Beebe are more common than people may realize.
And Sleeman should know - he directs a staff of scientists whose primary purpose is to investigate the nation's wildlife diseases from avian influenza to plague and white-nose syndrome in bats.
"The USGS NWHC provides information, technical assistance, research, education, and leadership on national and international wildlife health issues," Sleeman added.
According to USGS NWHC records, there have been 188 mortality events across the country involving 1,000 birds or more during the last 11 years (2000 - 2010). In 2009, individual events included one in which 50,000 birds died from avian botulism in Utah; 20,000 from the same disease in Idaho, and 10,000 bird deaths in Washington from a harmful algal bloom.
Mass-mortality events occur in other animal populations as well, according to the USGS NWHC. For example, prairie dog colonies in the West can be destroyed by sylvatic plague, which can then kill off the highly endangered black-footed ferret that preys on prairie dogs exclusively. The USGS NWHC is involved with developing vaccines, delivered through bait, which can immunize prairie dogs against plague.
In the 1970s and 1980s, most USGS NWHC die-off investigations involved large numbers of waterfowl deaths from avian cholera, avian botulism and lead poisoning; in the 1990s, the USGS NWHC was highly involved in investigating the emergence of West Nile virus in North America. In 2008, the USGS NWHC discovered the cause of white-nose syndrome, a fungal disease that has devastated cave-hibernating bat species in the Eastern U.S.
Public reporting of wildlife mortality events is important, and in 2010, the USGS Wildlife Disease Information Node initiated an experimental reporting system to facilitate this. Visit http://www.whmn.org/wher/ for more information.
More information on the USGS NWHC and its involvement in the recent bird die-off events can be found on the NWHC website.