Table 4. Results from GLM explaining changes in mesophilic bacterial density on spotless starling eggshells along the incubation period (changes between day 3 and day 12).
| Beta (SE) | df | F | P | |
|---|---|---|---|---|
| 2012 | ||||
| log pigmented feathers (1st) | -0.202 (0.077) | 1,50 | 6.85 | 0.012 |
| log unpigmented feathers (1st) | 0.305 (0.085) | 1,50 | 11.17 | 0.002 |
| 2013 | ||||
| log pigmented feathers (2nd) | 0.216 (0.082) | 1,60 | 6.91 | 0.011 |
| Feather treatment | 2,60 | 5.36 | 0.007 |
Nest lining material (pigmented and unpigmented feathers) before incubation started (1st) and few days before hatching (2nd) were included as continuous independent covariates. Experimental modification of green plants (i.e. with or without aromatic plants) and of feathers (i.e. pigmented, unpigmented or without feathers treatment) were included as factors with fixed effects. In 2013, we used a third experimental treatment that consisted on eggshell contamination at the time of egg laying. We only show final models with retained factors with p-values < 0.1. However, associated statistical significances of different factors did not change in full models (see S3 Appendix). Significant associations are in bold.