Do long-distance migrants use temperature variations along the migration route in Europe to adjust the timing of their spring arrival?

Arrival of long-distance migrants (LDMs) has been frequently linked to temperature by correlating the arrival dates with temperature from one or a few sites along the supposed migration route. We used a site-independent approach, and correlated the arrival dates of LDMs with the temperature gridded over the entire Europe to study the spatial extent of correlations. We found extensive and statistically significant spatial correlation patterns between the arrival dates and the monthly temperature during or a month preceding arrival. These correlations were in most cases strongest 500-2000 km from the sites of arrival. The correlations indicate that most of the LDMs slowed clown or speeded up migration according to yearly variations in temperature or linked phenology. This adjustment of migration speed along the migration route may help LDMs match their arrival to the annual variability of phenology in their breeding grounds.