A long-term comparison of laying date and clutch size in the Red-Backed Shrike (Lanius collurio) in Silesia, Southern Poland

In this paper laying date and clutch size of breeding Red-backed Shrike Lanius collurio in two time periods (1905-1925 and 1985-1999) in southern Poland are compared. Comparisons were made on two separate data sets: a museum collection and nest-cards from the Polish Nest Record Scheme. No significant differences between time of laying (median was 26 May in both periods) and clutch size (5.01 vs. 5.06, respectively) were found. The possibility of using museum collections and nest-cards to analyse long-term trends in life-history traits is discussed.