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Mid-Winter Temperatures, Not Spring Temperatures, Predict Breeding Phenology In The European Starling Sturnus Vulgaris, Tony D. Williams, Sophie Bourgeon, Allison Cornell, Laramie Ferguson, Melinda Fowler, Raime B. Fronstin, Oliver P. Love

Integrative Biology Publications

In many species, empirical data suggest that temperatures less than 1 month before breeding strongly influence laying date, consistent with predictions that short lag times between cue and response are more reliable, decreasing the chance of mismatch with prey. Here we show in European starlings (Sturnus vulgaris) that mid-winter temperature ca 50–90 days before laying (8 January–22 February) strongly (r2 =0.89) predicts annual variation in laying date. Mid-winter temperature also correlated highly with relative clutch size: birds laid later, but laid larger clutches, in years when mid-winter temperatures were lower. Despite a high degree of breeding synchrony (mean laying date …