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Free-living waterfowl residing in zoological and metropolitan parks in central Ohio, including Canada geese (Branta canadensis), mallard ducks (Anas platyrhynchos), and domestic waterfowl species, were investigated for fecal shedding of Campylobacter jejuni, Escherichia coli, Salmonella spp., and Pasteurella multocida. These bacteria may be important pathogenic organisms in zoonotic and epizootic infection and have been isolated from many free-living avian species. Some waterfowl populations, particularly the more sedentary tribes such as giant Canada geese (Branta canadensis maxima) have increased significantly in the last few decades, and now consist of many locally migrating, resident flocks within urban and suburban areas. Often birds are found congregating year round in protected sites such as zoological and metropolitan parks. The purpose of this thesis was to determine if free-living waterfowl are able to transmit E. coli, C. jejuni, Salmonella spp., and P. multocida to zoological collections or to zoo and metro park visitors and employees by investigating rates of bacterial shedding. Antimicrobial susceptibility patterns were also investigated for bacterial isolates to determine recent trends in microbial resistance and susceptibility patterns.Results of bacterial prevalence for the zoological setting included a 67%, 42%, and 1.8% isolation rate for E. coli, C. jejuni, and Salmonella spp., respectively. Escherichia coli prevalence observed for Canada geese was statistically higher (p≤0.0001) than for mallard ducks, but no difference in prevalence was noted for C. jejuni isolation between the two waterfowl species (p>0.05). All Salmonella spp. isolates were obtained from Canada geese, and were identified as S. typhimurium by the National Veterinary Services Laboratory. Results from six metro parks yielded isolation rates of 67%, 50%, and 0.2% for E. coli, C. jejuni, and Salmonella spp., respectively. Escherichia coli prevalence was significantly higher for mallard ducks than for Canada geese (p≤0.00001), but no difference was noted for C. jejuni prevalence between waterfowl species (p>0.05). One Salmonella spp. isolate was obtained from a mallard duck, which was identified by the National Veterinary Services Laboratory to be S. java, an organism typically associated with reptiles. Pasteurella multocida was not isolated from any of the fecal samples collected.The presence of E. coli, C. jejuni, and Salmonella spp. in fecal material of free-living waterfowl identifies such avian species as potential transmission sources of pathogenic bacteria for zoo animals and human visitors and employees in zoological and metropolitan parks. Although isolation rates of E. coli seemed to fluctuate between waterfowl species over time and between sites, C. jejuni isolation rates remain fairly constant in similar instances. Salmonella spp. may be intermittently shed in feces at low rates, but still represents a threat of transmission to other susceptible hosts. Lack of P. multocida isolation was expected, as presence of the organism is usually associated with visibly ill birds and all isolates were obtained from apparently healthy waterfowl. Hence, flocks included in the studies were not considered to be transmission sources of P. multocida, nor were they identified as reservoirs due to lack of P. multocida isolation.Antimicrobial susceptibility testing for both studies revealed that E. coli, C. jejuni, and Salmonella spp. isolates from free-living waterfowl in central Ohio are susceptible and resistant to a variety of antimicrobial agents, resulting in similar trends between sites. A recent emergence of quinolone resistance reported in the United States was not demonstrated among the isolates obtained in the study. For example, most bacteria isolated, regardless of species, was susceptible to ciprofloxacin. The research represented in these two studies identifies resident, locally migrating flocks of free-living waterfowl as possible transmission sources of potentially pathogenic bacteria to zoo animals, human visitors, and employees through fecal contamination of park settings.