Mosquitoes (IMAGE) University of South Florida Caption In this study, researchers found birds with higher levels of the stress hormone, corticosterone, were twice as likely to be bitten by mosquitoes that transmit West Nile virus. Credit University of South Florida Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.