Blackbirds are getting scarce in Edgar Allan Poe?s city.
As few as one in 10 crows survived years of the West Nile Virus in some parts of Baltimore and Washington, according to research published Thursday by the Consortium of Conservation Medicine in the journal Nature.
While crows are scavengers and often disliked, they play a key role in nature by cleaning up animal carcasses, said lead author Shannon LaDeau, a research scientist at the Smithsonian Migratory Bird Center in Washington.
Researchers noted the die-offs came in patches, with many in some places and none in others, she said.
Maryland appeared to be the epicenter of bird deaths, though that was partly because the data was not as good from New York, where the virus first hit, LaDeau said.
Mosquito-borne illnesses include West Nile Virus, St. Louis encephalitis, and Eastern Equine encephalitis, according to the Mississippi Department of Health, which has reported the first three human West Nile cases so far this year.
“It presents as a flu-like syndrome. It can get worse with the really elderly and the really young,” said Dr. Michael Zimring, director of the Center for Wilderness and Travel Medicine at Mercy Medical Center. “It can develop a sort of encephalitis ? an inflammation and infection of the nervous system.”
There is no vaccine for the human form of the illness he said, though human deaths are rare.
West Nile Virus, which is spread by mosquito bites, has infected 23,974 people, killing 962 over seven years, according to the Centers for Disease Control and Prevention.
But it takes a toll on other birds as well as crows. Populations of chickadees, Eastern bluebirds and robins in Maryland were at 68 percent, 52 percent, and 32 percent below expected levels, according to the Nature article.
The article combined 26 years of bird-breeding surveys to quantify what had been known anecdotally about the decimation of bird populations.
