Number of parasites, C. mexicanus (grey circles) and P. domesticus (black circles), was a negative function of the amount of cigarette butt material contained in the nest. Asterisk (*) represents regression line from an exponential model fitted to the data from both species.
Thermal traps with smoked butts attracted fewer mites than traps with non-smoked butts, regardless of the nest content. Non-smoked butts gathered more parasites from nests assayed during incubation than from empty nests or (non-significantly) than after hatching, presumably as some parasites remained attached to the chicks. Probability values from a variance component analysis (global) and from post hoc Bonferroni-corrected comparisons between treatments and nest contents. Probabilities in italics from Bonferroni-corrected individual comparison.