A Geometric Method for Determining Shape of Bird Eggs

Precise quantification of the oval of a bird egg can provide a powerful tool for the analysis of egg shape for various biological problems. A new approach to the geometry of a bird egg oval is presented here using a simple algebraic equation to fit all normal bird egg shapes. Only two parameters are needed in the equation for complete shape description of an egg oval to quantify the equation's capacity for curve fitting all species and shapes of bird egg ovals. The equation was fitted to egg silhouettes from a sample of 250 different bird egg species containing one egg per species. Standard regression analysis was used to fit the equation to each egg profile. The 99% CI for the curve fit acceptance rate was calculated to determine the equation's statistical significance for all species of bird eggs. Compared to the power series multiequation models (Preston 1968, Todd and Smart 1984), the equation used here is the simplest analytic description of a bird egg oval.