Abstract
Winter aggregations of waterfowl present unique opportunities for highly pathogenic avian influenza (HPAI) transmission and virus maintenance. During winter, waterfowl concentrate in high densities at refuges and wetland complexes, often sharing habitat with multiple species and age classes. These congregations, combined with reduced wetland availability in winter, create conditions that could amplify both direct transmission through bird-to-bird contact and indirect transmission through shared water resources. Using GPS-GSM transmitters on over 1,000 mallards (Anas platyrhynchos) wintering in Tennessee and elsewhere in the Lower Mississippi Alluvial Valley, we documented extensively local and constrained movements during winter, high spatial overlap among individuals, and frequent use of shared wetland habitats. Importantly, GPS-GSM tracked mallards that tested positive for HPAI H5N1 showed no differences in movement patterns, body condition, or survival compared to uninfected birds. These HPAI-positive birds maintained normal daily movement patterns, initiated spring migration slightly earlier than uninfected birds, and successfully completed similar migration distances. Notably, infected birds regularly shared space with uninfected individuals while maintaining typical movement behaviors, suggesting ongoing transmission opportunities within wintering populations. Daily movements between roosting and foraging sites may facilitate transmission between wild birds and domestic poultry, particularly in agricultural landscapes. Additionally, as waterfowl prepare for spring migration, their increased movement and mixing could expand the geographic scope of transmission. Understanding these winter behavior patterns of waterfowl and how HPAI infection affects them is crucial for predicting virus spread risk and implementing effective surveillance strategies.
Co-Author(s)
Claire S. Teitelbaum, Nicholas M. Masto, Cory J. Highway, Jeffery D. Sullivan, Walter N. Harrington, Lisa Kercher, Allison C. Keever, Rebecca L. Poulson, Deborah L. Carter, Abigail G. Blake-Bradshaw, Jamie C. Feddersen, Heath M. Hagy, Richard W. Gerhold, Richard J. Webby, and Diann J. Prosser
Abstract Category
Notable outbreaks, field and molecular epidemiology, and surveillance in wild birds