A presumptive natural West Nile virus outbreak occurred in 23 of 27 captive American White Pelicans (Pelecanus erythrorhynchos) located in Starkville, Mississippi. Twenty-one birds were confirmed positive through either reverse transcriptase PCR, immunohistochemistry (IHC) or complement fixation serological testing. Two additional birds were presumed positive by histological changes typically ascribed to West Nile virus. Two of the 23 infected pelicans had been previously implanted with a temperature monitor and served as case studies. These birds began showing clinical signs in July on day 27 and 30 post-placement, preceded by a reduction in food intake one day prior in both cases. Initial clinical signs observed in both birds included wing droop and lethargy and within 72 hours both birds displayed increased agitation and aggression during feeding. Here we detail the progression of disease caused by West Nile virus in two cases.