January 1, 2014
More Than Two Dozen Bald Eagles Fall Due To West Nile Virus Infection
[ Watch the Video: Bald Eagles Killed By West Nile Virus ]
Gerard LeBlond for www.redorbit.com - Your Universe Online
The symptoms that the eagles exhibited were head tremors, signs of seizures, wing paralysis, and weakness in the legs and feet.
The birds that died were from northern and central Utah and either found dead or ill, but later died during treatment. Five other eagles were found with similar symptoms, but are responding well to treatment.
Utah wildlife officials believe the eagles contracted the virus by eating Eared Grebes, a duck-like bird, that were infected and had recently died. Usually the virus is transmitted through mosquitoes during the warmer months. The grebes begin to arrive in October when the mosquitoes are still active and possibly became infected.
According to the CDC, the virus can be transmitted to birds of prey if they feed on an infected carcass. The West Nile Virus was first detected in North America in 1999 and has spread across the country as well as into Canada. It can remain in carcasses of infected birds for a few days.
Officials tested the eagles for toxins, chemicals, infections and viruses to determine the cause of death. Residents should not be concerned about the virus spreading, according to JoDee Baker, with the Utah Department of Health. She said in a statement, “Since the mosquitoes that transmit West Nile virus aren’t active in the winter, there’s no risk to the public’s health.”
Mark Hadley, a spokesman from the Utah Division of Wildlife Resources (DWR), said, “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.”
Around 750 to 1,200 bald eagles migrate to Utah beginning in November and stay until March.
These bald eagles seem to have died rather quickly after their arrival, according to Hadley. The eagles get most of their food from eating dead animals.
Wildlife officials state that the birds pose no threat to humans, but urges that people should not handle them if they are found. He did note that more eagles could become infected before the grebes begin to leave the area mid-January.
“Even though it’s difficult to watch eagles die, the deaths that have and still might occur won’t affect the overall health of the bald eagle population that winters in Utah or the overall population in the United States,” said Leslie McFarlane, the wildlife disease coordinator for the DWR.
“Every time grebes die, we send some of the dead birds to a laboratory for testing,” McFarlane said, according to Desert News. “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.”
She also stated, “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.”
In 17 years of service with the DWR, Hadley has never seen this many eagles die in such a short period of time. “This is definitely unusual,” he said.