Intrapopulation variation of egg size in the White Stork [Ciconia ciconia] in Southern Poland

White Stork (Ciconia ciconia) eggs were studied in Upper Silesia, Southern Poland. The measurements of eggs – their length, breadth, volume and elongation index were collected for 95 nests in years 1974–2002, and repeatability of these measurements was computed. Mean clutch size was 4.05 ± 0.82. Mean egg measurements were: 72.10 ± 2.18 mm, 52.19 ± 1.47 mm, 100.49 ± 6.92 cm³ and 1.38 ± 0.05, for length, breadth, volume and elongation index, respectively. Coefficients of variation for clutch means ranged from 1.68 (breadth) to 4.37 (volume). Mean repeatability estimates were 0.53, 0.68, 0.63, 0.58 for length, breadth, volume and elongation index, respectively. The results obtained suggest that one should expect relatively low or intermediate heritability of egg dimensions in population studied.