EGG SIZE AND REPRODUCTIVE STRATEGIES OF WESTERN PALEARCTIC BIRDS

To analyse the possible relationship between some ecological variables parameters and trends (r or K tendency) in the reproductive strategy of Palearctic birds, female size was platted against egg size and othe r parameters such as clutch-size or fledging age for the western Palea rctic bird families, and the differences were calculated between the v alues expected according to a purely arithmetic relationship and those actually found. It appears that, apart from some extreme cases of ada ptation to peculiar life styles, the key factors that account for the position of the various bird families within a positive or negative re sidual with respect to the arithmetic Values are food and nest type.