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Abstract
Birds within the order Anseriformes are considered an important natural reservoir of Influenza A virus (IAV), yet other species likely contribute to the maintenance, distribution, and evolution of IAV. This work focused on drivers of IAV infection dynamics in species in other avian orders that have garnered less attention. In the first study, we evaluated the importance of population immunity as a potential cause for which IAV subtypes are most commonly isolated from the IAV hotspot at Delaware Bay, New Jersey (DE Bay) in a given year. While we hypothesized that population immunity causes shifting IAV subtype dominance at DE Bay, our results suggested that IAV dynamics are subtype-dependent and population immunity has more of a bearing on which species is infected at DE Bay. In the second study, we determined the susceptibility of Mallards (Anas platyrhynchos) and Laughing gulls (Leucophaeus atricilla) to IAVs isolated from Ruddy Turnstones (Arenaria interpres morinella) at DE Bay in order to gain insight into potential sources and host ranges of these viruses. We found that Mallards were far more permissive to infection with most viruses, suggesting that transmission between Mallards and Ruddy Turnstones could occur. By contrast, host-adaptation of IAVs to Ruddy Turnstones may compromise the virus ability to be transmitted back to gulls. Finally, we evaluated the importance to IAV maintenance of a species not conventionally recognized as a significant host for IAV. The American White Ibis (Eudociums albus) is a wading bird that occupies aquatic habitats in the Southeastern United States. Through experimental challenge, and a multi-year, multi-season serosurvey, we determined that they are both susceptible and naturally exposed to IAV. Thus, they may represent a component of the IAV natural reservoir system. Collectively, the findings reported in this dissertation provide focused, new insight into the well-studied IAV system at DE Bay, while also providing support for broadening our concept of how IAVs are maintained in multi-species, avian communities.