Transmission-relevant behaviours shift with pathogen infection in wild house finches (Carpodacus mexicanus)

Host individuals who are infected with a pathogen may alter their behaviour in ways that influence transmission. We observed a marked population of house finches (Carpodacus mexicanus (Muller, 1776)) in Ithaca, New York, to test whether individuals change their behaviour at feeding stations when infected with a prevalent bacterial pathogen, Mycoplasma gallisepticum (MG). We found that house finches with conjunctival lesions consistent with MG infection fed for longer bouts of time than individuals without conjunctivitis. Furthermore, the same individuals that were observed both with and without conjunctivitis during 3 years of study were more likely to feed alone and associated in significantly smaller flocks when conjunctivitis signs were present. These results su-est house finches alter their foraging and social behaviour at feeding stations when visibly infected with MG. Since MG transmission is thought to primarily occur at feeders, these changes in host behaviour likely have important consequences for MG transmission dynamics.