DWR conducted testing on several bald eagles that died in Utah this month. Officials believe the eagles may have contracted the virus after eating infected eared grebes that died recently on the Great Salt Lake.
In the winter, bald eagles obtain most of their food by eating dead animals. Since all of the eagles that have died have been within flying distance of the lake officials believe the eagles may have contracted West Nile virus after eating grebes that died at the lake from the disease.
Leslie McFarlane, wildlife disease coordinator for the DWR, says more than 2 million eared grebes stop at the Great Salt Lake during their migration. Each year about one percent contract a bacterial disease called avian cholera and die.
"Every time grebes die," she says, "we send some of the dead birds to a laboratory for testing. Usually, avian cholera jumps out as the cause of death. This year, though, the initial laboratory results were not as conclusive. That led us to believe that something else might have killed the grebes this year."
As of December 31, 27 eagles had died in Utah. Twenty-one eagles of those birds died in the wild. The other six died at a rehabilitation centers. There are five additional eagles being treated at rehabilitation centers and officials say the appear to be responding well to treatments.