The weakening of eggshells of the laughing dove, <i>Streptopelia senegalensis</i> (Linn.)

Abstract

Eggshells of Streptopelia senegalensis dating from 1899 to 1983 were studied to determine whether a change had occurred in the mass of the shells, the length section, breadth (width) section, thickness and index. A significant difference was determined in both mass and index of the more recent eggs (after 1957) compared with older eggs. The two groups of eggs represent periods prior and subsequent to the introduction of agricultural pesticides in southern Africa. Although no definite link has been established the results merit further experimental studies to determine whether the observed changes could be ascribed to the increased usage of agricultural pesticides.