Large wildlife die-off events are fairly common, though they should never be ignored, according to the U.S. Geological Survey scientists whose preliminary tests showed that the bird deaths in Arkansas on New Year’s Eve and those in Louisiana were caused by impact trauma.
Preliminary findings from the USGS National Wildlife Health Center's Arkansas bird analyses suggest that the birds died from impact trauma, and these findings are consistent with the Arkansas Game and Fish Commission's statement. The State concluded that such trauma was probably a result of the birds being startled by loud noises on the night of Dec. 31, arousing them and causing them to fly 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 2-3 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., which is completing its analyses of the Arkansas and Louisiana birds. "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, Ark., and the smaller one near Baton Rouge, La., are more common than people may realize.
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