Dietary characteristics of Emus (Dromaius novaehollandiae) in semi-arid New South Wales, Australia, and dispersal and germination of ingested seeds

Abstract

The Emu (Dromaius novaehollandiae) eats a wide range of seeds and other plant material but little is known of the seeds eaten and dispersed in arid Australia. This study aimed to determine the species of seed and fruits eaten by Emus through the year and investigate the effect of the passage of seeds through the Emu gut on seed germination. Emu scats were opportunistically collected in all seasons of 2005 at Nanya Research Station, western New South Wales. Seeds of 29 plant species were retrieved, identified and counted from 221 scats. Seeds of perennial species, such as Belah (Casuarina pauper), Ruby Saltbush (Enchylaena tomentosa), Common Emu-bush (Eremophila glabra) and Nitre-bush (Nitraria billardierei), predominated. Seed composition of scats was more diverse in summer than in winter, autumn and spring. Seeds of Common Emu-bush, Berrigan (Eremophila longifolia) and Sweet Quandong (Santalum acuminatum) showed no germination after passage through the gut. Ruby Saltbush and Nitre-bush showed very low germination rates. The Emu is a generalist feeder, capable of ingesting and dispersing large numbers of plant species. Through high seed consumption and long gut-retention time, Emus could potentially play a significant role in long-distance dispersal of seeds and, through such dispersal, in the vegetation dynamics of arid Australia.