Biologists at Washington University (St. Louis) have demonstrated that the more diverse a bird population is in an area, the less humans have a chance of being exposed to West Nile Virus WNV). “The bottom line is that where there are more bird species in your backyard, you have much lower risk of contracting West Nile Fever,” said Brian Allan, doctoral candidate in biology in Arts & Sciences at Washington University in St. Louis.

“The mechanisms are similar to those described for the ecology of Lyme disease. Most birds are poor reservoirs for West Nile Virus, and so mosquito bites taken on them are ‘wasted’ from the perspective of the virus. Where many bird species exist, very few mosquitoes get infected, and so we humans are at low risk. A few bird species are highly competent reservoirs, and these tend to occur in urbanized and suburbanized areas where bird diversity suffers.”

The characteristic reservoir species in urban situations are Amercan Crows, grackles, House Finches, Blue Jays, House Sparrows, and American Robins (with the robin being the most prolific carrier of WNV). Robins are acclimated to humans, and by feeding on the ground are relatively easy prey for mosquitoes.

The bottom line of this study is that even in urban and suburban situtations, human health is positively impacted by a healthy, diverse bird population. A more detailed explanation of the finding are available on the Washington University in St. Louis website.