The mysterious disease responsible for killing more than 27 bald eagles in Utah since December 1st (see http://www.examiner.com/article/mysterious-deaths-of-bald-eagles-raising...) is a mystery no more, according to lab tests that have identified it as West Nile virus.
The birds, all found in the central and northern parts of the state all died after suffering from seizures, head tremors, weakness in their legs and had paralized wings. Although most of the birds were already dead (or died shortly) after being discovered, officials report that five seem to be responding well to treatment at a wildlife rehabilitation center.
West Nile, common in northeastern states such as New York and Connecticut, is spread by mosquitoes, and despite the cold weather, officials at the Utah Division of Wildlife believe that the eagles may have gotten WNV after eating infected eared grebes that had begun migrating to the state in October when mosquitoes were still active.
The grebes, a duck-like bird can regularly be found around the Great Salt Lake where they tend to feed on brine shrimp and alkali flies before migrating to islands in the Gulf of California for the winter. Many, however, do remain near large bodies of open water in Utah and other western states as well.