FIGURE 4.

Relationship between diet and the bactericidal capacity (mean proportion of killed bacteria relative to colony growth on a control plate ± SE) against (a) Escherichia coli and (b) Salmonella paratyphi. Measurements were made before and 30 days after implementation of the experimental diet. There was no effect of sex, diet, or time on the ability of ibis blood to kill either bacterial species. There was a significant diet × time interaction on the bactericidal capacity against S. paratyphi. While birds in the natural diet group tended to get better at killing S. paratyphi, birds receiving anthropogenic tended to get worse, indicating that the implementation of the experimental diet influenced the ability to kill S. paratyphi. The bacterial killing capacity for both bacterial species was arcsine transformed for analyses, but raw data are presented here. Numbers in the bars indicate sample sizes. For these box plots, the boxes show the 25th and 75th percentile values, the line within shows the median value, and the whiskers show the minimum and maximum of the dataset, with additional data points showing potential outliers in the dataset