West Nile Virus (WNV) first appeared in the western hemisphere in 1999, and has since spread across the United States and into Mexico and the Caribbean. It has been hypothesized that WNV has spread rapidly via migratory birds, and that various avian species may facilitate viral amplification during winter months. The goals of this research were to determine the role of American Tree Sparrows (Spizella americana) in the spread of WNV during their igrations and to determine the role of the Northern Cardinal (Cardinalis cardinalis) in winter survivorship and subsequent spring amplification of WNV. Additional wintering avian species were sampled to provide a general survey of the prevalence of WNV in winter in south-central Kansas. Blood samples were taken from the brachial vein of migratory and wintering birds captured using mist nets at four wintering feeding stations at the Wichita State University Field Station. Some samples were taken from retrapped birds within a single winter to determine if winter transmission occurs. Some birds were resampled in consecutive winters to monitor seroconversion rates. Analysis of serum samples were performed, in triplicate, using an epitope-blocking ELISA. The current study was conducted during the consecutive winters of 2003-04 and 2004-05. It was concluded that resident species had an increased incidence of WNV exposure when compared to that of migratory species. This difference suggests that migratory species may not have as important a role in the dissemination of WNV as first hypothesized. Also, minimal, if any, winter transmission occurs on communal feeding grounds. Viral amplification during the winter was not demonstrated, although one individual seroconverted during a single winter. / Thesis (M.S.)--Wichita State University, Dept. of Biological Sciences / Includes bibliographical references (leaves 35-39)