212 * Corresponding author Folia Zool. – 57(3): 212–220 (2008) Migration distance and the effect of North Atlantic Oscillation on the spring arrival of birds in Central Europe Dedicated to Professor Karel Hudec in honour of his 80th birthday Zdeněk HUBÁLEK* and Miroslav ČAPEK Institute of Vertebrate Biology ASCR, v. v. i., Květná 8, CZ-603 65 Brno, Czech Republic; e-mail: zhubalek@ivb.cz, capek@ivb.cz Received 29 November 2007; Accepted 17 March 2008 Abstrac t. Mean annual first arrival dates (FAD) of 45 migratory bird species recorded in Moravia (Czech Republic, c. 49º N) in 109 spring seasons between 1881 and 2007 were correlated with the preceding winter (December to March) North Atlantic Oscillation (NAO) index. The arrival of birds occurred significantly earlier following high NAO winter index values (those result in spring warmer than normal in central Europe) in all short-distance migratory species with a European or North African winter range, whereas the arrival timing did not correlate significantly with the seasonal NAO index in long-distance migrants having sub-Saharan winter range. When the values of Pearson coefficient between NAO and FAD were correlated with the migration distance of all 45 bird species, the correlation was remarkable and significant (p<0.001): r = 0.848 for the distance to central locations of winter range, and r = 0.822 for the northern limits of the wintering area. The migration distance was thus responsible for 68–72 % of variation in the regression of birds’ arrival on NAO winter index in central Europe. The data are robust (this is the longest avian phenological record analyzed for correlation with NAO in Europe), and indicate different mechanisms that govern timing between short-distance and long-distance migrants in their departure from wintering areas. Key words: climate, NAO, phenology, temperature, weather Introduction North Atlantic Oscillation (NAO) system is the major promoter of annual weather fluctuation in Europe and eastern North America (W a l l a c e & G u t z l e r 1981, Hurrell 1995, Yoo & D ’ O d o r i c o 2002). The system can be described quantitatively using monthly, seasonal or annual indices that make possible an analysis of the correlation with other phenomena (S t e n s e t h et al. 2003). A number of papers have reported the effect of NAO on the timing of spring migration of birds (arrival dates: F o r c h h a m m e r et al. 2002, J o n z é n et al. 2002, H u b á l e k 2003, 2004, H üppop & Hüppop 2003, Sokolov & Kosarev 2003, K a ň u š č á k et al. 2004, S i n e l s c h i k o v a & S o k o l o v 2004, Vähätalo et al. 2004, Z a l a k e v i c i u s et al. 2006) and their breeding phenology (first egg laying date) and productivity (F o r c h h a m m e r et al. 1998, Przybylo et al. 2000, Saether et al. 2000, Both & V i s s e r 2001, M ø l l e r 2002, N o t t et al. 2002, Sanz 2002). In this study, an unprecedentedly long record (109 years) of avian spring phenology data from Moravia (Czech Republic) has been evaluated for correlation with seasonal NAO index. Several records of FAD published (e.g. S p a r k s & Carey 1995, Lehikoinen