Effects of selected covariates on mean hatching date of the red-backed shrike.

Modelled by GAMM was the effect of mean May temperature (T_MAY), mean seasonal daily mortality rate (DMR) and ln-transformed breeding density [ln(density)] across four sites in the Czech Republic. Study site was included as a random effect. The fitted smooth functions indicate effect size with its 95% confidence intervals of a given factor (smoothing terms for the effect of T_MAY: edf = 1, t = −3.50, p = 0.0011; DMR: edf = 1, t = 1.50, p = 0.14 and ln(density): edf = 1, t = −5.36, p<0.001). Partial residuals of the response are obtained by varying the effect of the explanatory variable concerned, while leaving all other variables fixed. See Fig. 1 for further explanations. See Fig. S2 for site-specific analyses and values on the original scales.