Practical method of estimating fresh mass of Ad,lie penguin eggs

Fresh egg mass (FEM) is an important measure as it relates to many allometric relationships. Ad,lie penguin (Pygoscelis adeliae) eggs, as other bird eggs, begin to lose weight as soon as they are laid but their linear dimensions remain constant. The FEM of an Ad,lie penguin's egg can be estimated within 1% from the relationship FEM = 0.564 x LW (2), where L is the length and W is the width. The constant 0.564 was calculated by weighing the eggs after replacing the air cell with water. The calculated mean egg mass agrees well with that obtained by weighing eggs after replacement of the air cell with water (r (2) = 0.996). This method of estimating FEM based on linear measurements is easily applicable in the field.