Correlation of mechanical properties of avian eggshells with hatching strategies

Abstract

Mechanical tests, including experiments designed to simulate the pipping and hatching processes, were combined with acoustic‐emission analysis to show that the eggshells of some avian species (e.g. domestic hen and domestic duck) may be classified as hard and brittle, and others (e.g. Japanese quail and pigeon) as tougher and more flexible. Laboratory and field studies of hatching, and observations of cine films, demonstrated that these differences in the mechanical properties of the shell were related to hatching technique. Whilst chicks in hard brittle Shells made relatively few holes before pushing away a cap, the hatching of chicks contained in tougher, more flexible Shells was characterized by extensive Perforation along a latitude of the shell. Indeed, the latter often continued to perforate the shell for more than a complete revolution before pushing away a cap. The results are then discussed in relation to avian nest environment.