Results of multilevel Poisson regression with nest ID as a random factor.

Rate ratios (95% confidence intervals) are shown with chi2 or z test statistics and p values. An observation–level random effect was included to model possible overdispersion. Variance of i) random effects “nest ID”: 0.076 (95% C.I.: 0.035–0.17), p<0.05 and ii) observation-level random effect: 0 (exact 1.86e-23), n.s. The overall model explained 28.7% of the variance of which the random factor nest ID explained 13.2% and the fixed effects nest base, distance and precipitation in April, May and June 15.5%.