|
Résumé :
|
Bea-eaters arrive in Rheinland-Pfalz in May, with arrival dates during an eleven year study period (2003-2013) between May 4th and May 24th. Key objective of this study was to analyze the correlation of the arrival date with the mean values of temperature, precipitation and sun shine duration of the months April and May. None of the April dates shows a significant relationship to the arrival date, but all factors in May are significantly correlated. Comparing these three factors, we can show that sunshine duration has the most significant impact, followed by the precipitation amount and the medium temperature in May. Combining all three single factors to one weather index (KLI) it will increase the correlation coeffcient again. We discuss the results in the light of the current climate change impacts. The increasing temperature in summertime will cause a northward shift of the July-isotherms and an increase of insect supply during the main feeding period, followed by an increase of body condition of Bee-eater offspring. This will force the establishment of the species in Germany. But further studies are needed to analyze the dependence of large-scale weather situations with the migration phenology of Bee-eaters. These insights would help to understand the current spectacular range expansion of the species at the northwestern edge of its breeding distribution.
|