SALT LAKE CITY (AP) — The mystery illness that killed 27 bald eagles in Utah this month appears to be West Nile virus, state officials said Tuesday.
The Utah Division of Wildlife Resources said in a statement Tuesday laboratory tests done on some of the first birds found indicated they died from West Nile virus.
Since Dec. 1, officials have found the birds in northern and central Utah. All were either dead or ill and later died during treatment.
The eagles displayed similar symptoms, including head tremors, signs of seizures, weakness in legs and feet and a paralysis of the bird’s wings.
Beyond the 27 that died, officials said five eagles were being treated at a wildlife rehabilitation center Tuesday. They appeared to be responding well to treatment, officials said.
Utah wildlife officials aren’t sure how the eagles caught the virus, but they suspect the birds contracted it by eating eared grebes infected with the virus and died recently.
West Nile virus, which is spread by mosquitoes, usually infects eagles and other birds during warmer months.
Mark Hadley, a Utah Division of Wildlife Resources spokesman, said the grebes, a duck-like aquatic bird, start arriving in Utah in October, when mosquitoes are still active.
“It’s possible that those grebes got bit by mosquitoes after they got here when they arrived in the fall, and it just took a while for them to die,” he said.