Boundary Layers of Bird Eggs: Do They Ever Constitute a Significant Barrier to Water Loss?

A mathematical model consisting of semiempirical equations was used to calculate boundary-layer conductances for transport of water vapor from bird eggs in free convection regimes. The model accurately predicts the boundary-layer conductance of model "eggs" fabricated from 2% agar. Predictions based on the mathematical model show that bird eggs smaller than about 10 kg have boundary-layer conductances greater than 10 times the total (boundary-layer, cuticle, shell, and membrane) conductance of the eggs. Thus, it can be inferred that boundary layers probably never constitute a significant barrier to loss of water from eggs of birds.