Eggs of extinct dwarf island emus retained large size. (26th May 2021)

• Record Type: Journal Article
• Authors: Hume, Julian P.; Robertson, Christian
• Is Part Of: Biology letters. Volume 17:Number 5(2021)
• Publication Date: 2021-05-26
• Subjects: extinction -- dwarfism -- adaptation -- Dromaius novaehollandiae diemenensis -- Dromaius novaehollandiae minor -- Dromaius novaehollandiae baudinianus; Biology -- Periodicals; 570.5
• DOI: 10.1098/rsbl.2021.0012
• Languages: English
• ISSNs: 1744-9561

Abstract

Abstract : 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 the 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 seemingly had a slightly thinner eggshell. We provide possible reasons why these phenomena occurred.