West Nile Virus Outbreak Kills Tens of Thousands of Birds
Posted by feww on January 1, 2014
MASS DIE OFF of BIRDS
Unprecedented wintertime outbreak of West Nile virus caused mass die off of birds: Officials
An unusual wintertime outbreak of West Nile virus in Utah killed at least 27 bald eagles in December and more than 20,000 water birds since November, said the Utah Division of Wildlife Resources.
Officials discovered the dead or dying birds in northern and central Utah. The sick bald eagles, which died during treatment, all displayed similar symptoms including head tremors, seizures, paralysis in the wings, and weakness in legs and feet.
This undated photo released by the Wildlife Rehabilitation Center in Northern Utah shows a bald eagle that was brought into the center for treatment, but eventually died. Credit: Wildlife Rehabilitation Center of Northern Utah/via AP.
The eagles most probably contracted the disease after preying on sick or dead water birds, namely Eared Grebe [Black-neck Grebe], that were infected by the West Nile virus, according to Leslie McFarlane, a Utah wildlife disease coordinator.
“This is really kind of undocumented. Eagles have been known to feed on birds infected with West Nile virus but the transmission hasn’t happened on this large of a scale. And the total number of birds we’re talking about is on a grand scale that may not have been seen before,” she said.
“Some 20,000 of the water birds have died in and around the Great Salt Lake since November in an outbreak that may be a record in North America, McFarlane said. Initial testing suggested an infectious bacterial disease such as avian cholera caused the deaths, but findings released on Tuesday showed West Nile virus was the culprit,” said a report quoting McFarlane.
The fall is quite long in Utah, and provides for an extended breeding season for mosquitoes into late October, she said; however, it may be impossible to determine whether grebes contracted the disease in the state, or were infected by West Nile virus migrating there.
Up to 1,200 bald eagles migrate to wintering grounds in Utah each year, and the death toll could rise, said McFarlane.