Bird Diversity and the West Nile Virus, Part 2

A few months ago, I wrote about a study that found that greater bird diversity reduces the chances of human infection with the West Nile Virus. Now a second article has reported the same finding with some of the same data (e.g., the Breeding Bird Survey) as well as some field work of their own.

Allan and numerous graduate students began the research five years ago as they just entered graduate school and the topic of West Nile Virus was just beginning to receive lots of attention and the ecology of the organism hadn't been studied much. They identified a variety of field sites, both urban and rural, with their base of operations at Washington University's Tyson Research Center, a facility 22 miles west of St. Louis comprised of 2,000 acres of woods, glades and prairie.

They performed bird surveys at the sites, put up a variety of mosquito traps and studied different mosquito species and their ability to transmit the virus. Using kits provided by the Center for Disease Control, they tested the mosquitoes and found three positive pools.

"The infection rates are actually remarkably low, with maybe one in 1,000 carrying WNV," Allan said....

According to the researchers, they found that diversity is important both in the number of species and their proportions to each other. It does little good to have ten species in an area if two or three predominate. The ones most likely to predominate, like grackles and robins, are also the most likely to carry West Nile Virus and spread it to humans via mosquitos.

Protection from disease is yet another reason to protect wildlife diversity.