Physiological parameters provide relevant information on the general physical condition of freeliving birds. Blood parameters related to immune function, nutrition, and oxidative stress of Kelp Gulls (Larus dominicanus) that use fishery waste sites as feeding sites are reported. The presence of zoonotic bacteria in cloacal swabs was also assessed. Ranges of hematocrit, total proteins, glucose, and leukocyte counts were similar to those reported for other gull species and healthy birds in general. Heterophil and lymphocyte percentages were the only parameters affected by handling time of the birds. Reports of bacterial agglutination as an index of humoral innate immunity and oxidative stress makers are the first for the species. Kelp Gulls showed infection prevalence of 60% with Corynebacterium sp. and 30.5% with enteropathogenic Escherichia coli. Data presented here constitute a valuable contribution for future comparative studies and as baseline for clinical work.