Entomologist Dan Springer has noticed quite a few dead birds lately. Typically, that would be a cause for concern since birds are often the first victims when the West Nile virus strikes.
But Springer works for Shelby County Vector Control, the agency that tests mosquitoes annually for the West Nile virus, and so far this year, the virus hasn't been found in local mosquitoes.
So what's killing area birds? No one can say for sure, but experts suspect the dry weather may be the culprit.
"I've noticed a tremendous amount of dead baby birds, certainly a lot more than last year," says Springer. "I think the drought may have something to do with it."
According to the National Weather Service's Memphis office, the months of March through May were the driest on record since 1931. During the three-month period, less than 7 inches of rain were recorded.
"On March 31st, we had a little over an inch and a half of rain," says Marlene Mickelson, a meteorologist with the National Weather Service. "I've been seeing the birds, too, and I've thought it could be the lack of rain. All the little ponds are drying up."
Roughly 13 inches of rain have been recorded in Shelby County since January 1st. That's almost 13 inches less than average, meaning the area has only received half of its usual amount of rain.
"Heat is going to be a factor. Water supply is reduced. Even the available insects and berries and wild foods are reduced because of extreme heat," says Herb Roberts, an animal curator at the Memphis Zoo. "If you combine being a young, naive bird with limited food availability and extreme heat, I'd be surprised not to see birds dying. I've seen a few dead youngsters in my backyard, mostly blackbirds, starlings, and sparrows."
But Roberts is not ruling out the possibility that the West Nile virus may be playing a part in increased bird deaths. "Typically, it tends to hit crows, jays, and magpies. Every year, a few more of those are going to succumb to West Nile," Roberts says. "Five years ago, there were a number of blue jays around. Now there aren't many."
The West Nile virus is believed to have traveled to the United States from Uganda in 1999 via an infected bird or mosquito on a plane or ship. It has infected 23,974 people since then and at least 962 people have died from infections.
Springer admits that the birds could be dying from West Nile that they contracted last summer.
Humans contract the virus through a bite from an infected mosquito. Since early May, Vector Control has been trapping mosquitoes in 164 locations around the county. The insects are sent to the state for testing.
Whether the bird population is being affected by the drought, West Nile infections, or both, Springer says humans shouldn't worry about contracting West Nile until infections are found in mosquitoes.