Eggs of extinct dwarf island emus retained large-size: Electronic supplementary material

Islands off southern Australia once harboured three subspecies of the mainland emu (Dromaius novaehollandiae), the smaller Tasmanian emu (D. n. diemenensis), and two dwarf emus, King Island emu (D. n. minor) and Kangaroo Island emu (D. n. baudinianus), which all became extinct rapidly after discovery by human settlers. Little was recorded about their life histories and only a few historical museum specimens exist, including a number of complete eggs from Tasmania and a unique egg from Kangaroo Island. Here we present a detailed analysis of eggs of dwarf emus, including a first record of an almost complete specimen from King Island. Our results show that despite the reduction in size of all island emus, especially the King Island emu that averaged 44% smaller than mainland birds, the egg remained similar-sized in linear measurements, but less in volume and mass, and had slightly thinner eggshell. We provide possible reasons why these phenomena occurred.