Carry-Over Effects of Temperatures at Wintering Grounds and Migration Routes on the Timing of Spring Migration of Dunnock Prunella modularis on the Southern Baltic Coast

Climate change is altering the timing of bird migration, yet its long-term effects on medium-distance migrants remain poorly understood. We investigated how temperature conditions across Europe influence the timing of spring passage of the dunnock at the southern Baltic coast. Using daily standardised mist-netting data collected during spring migration (26 March–16 May) at Hel Bird Ringing Station over 1965–2025, we examined temporal changes in successive phases of passage and migration duration (MD). All migration phases advanced 5–8 days over the study period, but MD remained stable. All phases of passage were early with warm springs along migration routes in Central and Southern Europe. Warm winters were associated with delay in the first and the last phases of passage. The first phase of passage was early after warm early summers the previous year. We suggest that climate warming in Europe benefits dunnocks, creating favourable conditions for foraging, early breeding and two clutches, which carry over to subsequent life stages, as indicated by our results. However, the decline in dunnock numbers across Europe suggests that anthropogenic habitat changes and more frequent extreme weather events might counteract the positive effects of increasing temperatures.