Discussion
In this study, we found that the eggshells of four of the five species of Apteryx (Brown kiwi, Rowi, Roroa, and Haast tokoeka) were different enough to be assigned to their corresponding species using morphological characters. Whether these differences are due principally to phylogeny or ecology is debatable. Some of the species have suffered severe contraction to their ranges and all individuals left remain in a single population (i.e. Rowi and Roroa). Eggshells’ characteristics within a species (i.e. chickens) are known to be affected by environmental conditions (Rahn et al. 1982), and other studies have shown that the characteristics we measured in this study are strongly affected by the environmental conditions that individual birds live in (Winkler and Sánchez-Villagra, 2006; D’Alba et al., 2017). Therefore, in the next paragraphs we will discuss the possible ecological conditions that could explain these characters.