Song preferences in female starlings.

<p>The percentage of time spent by females on the perch adjacent to song playback from male starlings in the three treatment groups; control (open bars); E2 dosed (hatched bars); and chemical mixture dosed (black bars). Playback from the mixture group was preferred over playback from E2 dosed males (<i>t</i>₁₀ = 2.42, <i>P</i> = 0.035); Playback from the mixture group was preferred over song from control males (<i>t</i>₉ = 2.57, <i>P</i> = 0.029). There was no significant preference between control and E2 dosed playback (<i>P</i>>0.05); Graphs show mean+s.e.m. * = <i>P</i><0.05.</p

Song production in male starlings exposed to chemicals.

<p>The song production of male starlings in three treatment groups: control (open bars); E2 dosed (hatched bars); and the chemical mixture dosed (black bars) (a) Total time spent singing (sec/h). (b) Number of song bouts per hour. (c) Song bout duration (s) d) Repertoire size. Graphs show means+s.e.m. There was a significant effect of the experimental manipulation on the time spent singing between the treatment groups (ANOVA, <i>F_{2, 24}</i> = 6.15, <i>P</i> = 0.007). Bonferroni pairwise comparison post-hoc tests showed that the males that received the mixture of chemicals spent significantly longer singing than the control males (<i>P</i> = 0.009) and the E2 group (<i>P</i> = 0.028). There was a significant effect of treatment on the number of song bouts sung by the males (ANOVA, <i>F_{2, 23}</i> = 9.16, <i>P</i> = 0.001). Males in the mixture treatment group sang more song bouts than the control males (<i>P</i> = 0.004) and the E2 males (<i>P</i> = 0.002). Mean song bout duration was significantly longer for males in the mixture treatment group compared to the control males (ANOVA, <i>F_{1, 11}</i> = 5.842, <i>P</i> = 0.034). Finally, there was a significant effect of the experimental manipulation on the repertoire size of male starlings (ANOVA <i>F_{2, 16}</i> = 4.39, <i>P</i> = 0.030). The males in the mixture group had significantly greater repertoire size than males in the control group (Bonferroni pairwise comparison post-hoc tests <i>P</i> = 0.042). * = <i>P</i><0.05; ** = <i>P</i><0.01.</p

HVC size in male starlings exposed to chemicals.

<p>a) HVC volume (mean+s.e.m.) in the three treatment groups; control (open bars); E2 dosed (hatched bars); and the chemical mixture dosed (black bars) (ANOVA, <i>F</i>_{2, 32} = 4.46, <i>P</i> = 0.019). HVC volume of the males in the mixture group was significantly larger than in males in the control group (Bonferroni pairwise comparison post-hoc tests <i>P</i> = 0.032), but there were no significant differences in the HVC volume between males in the E2 and control groups (<i>P</i>>0.05) or between males in the E2 and mixture groups (<i>P</i>>0.05) * = <i>P</i><0.05. b) Photomicrograph of an HVC from (i) a chemical mixture treated male and (ii) a control male. Arrows indicate the borders of HVC. Scale bar = 200 µm.</p

Immune function in male starlings exposed to chemicals.

<p>The immune function of male starlings in three treatment groups; control (open bars); E2 dosed (hatched bars); and the chemical mixture dosed (black bars) (a) Cell-mediated immune function was measured as wing web swelling of both wings, 24 hours after injection with phytohaemagglutinin (PHA). Treatment had a significant effect on cell-mediated immune function (ANOVA, <i>F</i>_{2, 32} = 12.16, <i>P</i><0.001). Bonferroni pairwise comparison post-hoc tests showed that the immune function of males in both chemically dosed groups (E2 or mixture) was significantly lower than that of the control males (E2 versus control <i>P</i><0.001, mixture versus control <i>P</i> = 0.001) but there was no significant difference between males in the E2 and mixture groups (<i>P</i>>0.05). (b) The secondary humoral response following an intraperitoneal injection of sheep red blood cells (SRBC). Treatment had a significant effect on the secondary humoral response to SRBC (ANOVA, <i>F</i>_{2, 32} = 10.98, <i>P</i><0.001). Bonferroni pairwise comparison post-hoc tests showed that the mean response of the males in both dosed groups (E2 or mixture), was significantly lower than the mean of the control males (E2 versus control <i>P</i><0.001, mixture versus control <i>P</i> = 0.001), but there was no significant difference between the E2 treated and the mixture treated males (<i>P</i>>0.05). Graphs show means+s.e.m. ** indicates <i>P</i><0.001.</p