Dissecting microscope
The pore density of the three species eggshells was observed under a dissecting microscope (Olympus SZX12). Three eggshell fragments from the equatorial region of Brown Kiwi (13), Rowi (12), and Haast Tokoeka (10) were washed in an ultrasonic bath filled with deionized water to remove the plugs from the pores, let air dry and stained with an alcohol-based solution of Malachite green (1%). The eggshells were placed on paper towels and two drops of the dye were applied to the inner eggshell surface. The eggshells were let to set to allow the dye to penetrate the pores without staining the cuticle (Figure 2C).
The eggshells were observed under stereo microscope (Olympus SZX12) and photographed using an attached camera (Olympus S30) and then the pores were individually counted using ImageJ. The eggshells from the same individuals were later used in the Water Vapour Conductance experiments. This way the average pore density was estimated (pores/cm2).