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Abstract
Previously, we found that urban American white ibis (Eudocimus albus) shed a high prevalence of Salmonella spp. Mercury (Hg) is a common wetland contaminant that can cause immunosuppression in wading birds and potentially increase susceptibility to gastrointestinal colonization with Salmonella. We hypothesize that white ibis populations acquire more Hg in high urbanization areas (when compared to those that forage primarily in low urbanization areas) and that the Hg concentrations of ibis is positively correlated with Salmonella shedding. Contrary to what was expected, we found a significant negative correlation between average Hg concentration and average capture site urbanization level using linear regression (R2=0.327, p=0.026, unweighted R=-0.572, weighted R=-0.608). Additionally, using Wilcoxon rank sum tests, we found no significant difference in Hg concentration between Salmonella positive and negative ibis among low (W=259, p=0.622), high (W=329, p=0.758), or overall (W=1170, p=0.596) urbanization capture sites, likely due to high variability among free-roaming ibis.