Dietary characteristics of Emus (Dromaius novaehollandiae) in semi-arid New South Wales, Australia, and dispersal and germination of ingested seedsHeath Dunstan A , Singarayer K. Florentine A C , Maria Calviño-Cancela B , Martin E. Westbrooke A and Grant C. Palmer A
A Centre for Environmental Management, School of Science, Information Technology and Engineering, University of Ballarat, PO Box 663, Ballarat, Vic. 3350, Australia.
B Department of Ecology and Animal Biology, University of Vigo, EUE Forestal, Campus Universitario, E-36005 Pontevedra, Spain.
C Corresponding author. Email: firstname.lastname@example.org
Emu 113(2) 168-176 https://doi.org/10.1071/MU12061
Submitted: 2 August 2012 Accepted: 8 November 2012 Published: 15 February 2013
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.
Additional keywords: arid landscapes, Eremophila, fragmentation, scat, Mallee.
ReferencesAnon. (1999). ‘S-PLUS 2000. Guide to Statistics. Vol. 2.’ (Mathsoft Inc.: Seattle, WA.)
Baskin, C. C., Thompson, K., and Baskin, J. M. (2006). Mistakes in germination ecology and how to avoid them. Seed Science Research 16, 165–168.
| Mistakes in germination ecology and how to avoid them.CrossRef |
Bell, D. T. (1999). Turner Review No. 1. The process of germination in Australian species. Australian Journal of Botany 47, 475–517.
| Turner Review No. 1. The process of germination in Australian species.CrossRef |
Benvenuti, S. (2007). Weed seed movement and dispersal strategies in the agricultural environment. Weed Biology and Management 7, 141–157.
| Weed seed movement and dispersal strategies in the agricultural environment.CrossRef |
Biser, J. A. (1998). Really wild remedies – medicinal plant use by animals. Zoogoer 27, 1.
Booth, R. E., and Hendry, G. A. F. (1993). Seed viability and germination. In ‘Methods in Comparative Plant Ecology’. (Eds G. A. F. Hendry and J. P. Grime.) pp. 10–13. (Chapman and Hall: London.)
Brunner, H., Harris, R. V., and Amor, R. L. (1976). A note on the dispersal of seeds of blackberry (Rubus procerus P. J. Muell) by Fox and Emus. Weed Research 16, 171–173.
| A note on the dispersal of seeds of blackberry (Rubus procerus P. J. Muell) by Fox and Emus.CrossRef |
BOM (2005). Climate averages – Wentworth recording station. Bureau of Meteorology, Canberra. Available at http://www.bom.gov.au/climate/averages/tables/cw_047053_All.shtml [Verified 2 January 2013].
Cain, M. L., Milligan, B. G., and Strand, A. E. (2000). Long-distance seed dispersal in plant populations. American Journal of Botany 87, 1217–1227.
| Long-distance seed dispersal in plant populations.CrossRef | 1:STN:280:DC%2BC3Mngt12ntw%3D%3D&md5=4532a696374c76774d73a22638f4e621CAS |
Calviño-Cancela, M. (2011). Seed dispersal of alien and native plants by vertebrate herbivores. Biological Invasions 13, 895–904.
| Seed dispersal of alien and native plants by vertebrate herbivores.CrossRef |
Calviño-Cancela, M., Dunn, R. R., van Etten, E. J. B., and Lamont, B. (2006). Emus as non-standard seed dispersers and their potential for long-distance dispersal. Ecography 29, 632–640.
| Emus as non-standard seed dispersers and their potential for long-distance dispersal.CrossRef |
Calviño-Cancela, M., Fernandez, C. A., and Rivera, A. C. (2007). European Pond Turtles (Emys orbicularis) as alternative dispersers of ‘water-dispersed’ Waterlily (Nymphaea alba). Ecoscience 14, 529–534.
| European Pond Turtles (Emys orbicularis) as alternative dispersers of ‘water-dispersed’ Waterlily (Nymphaea alba).CrossRef |
Calviño-Cancela, M., He, T., and Lamont, B. B. (2008). Distribution of myrmecochorous species over the landscape and their potential long-distance dispersal by Emus and Kangaroos. Diversity & Distributions 14, 11–17.
| Distribution of myrmecochorous species over the landscape and their potential long-distance dispersal by Emus and Kangaroos.CrossRef |
Commander, L. E., Merritt, D. J., Rokich, D. P., and Dixon, K. W. (2009). Seed biology of Australian arid zone species: germination of 18 species used for rehabilitation. Journal of Arid Environments 73, 617–625.
| Seed biology of Australian arid zone species: germination of 18 species used for rehabilitation.CrossRef |
Davies, S. J. J. F. (1963). Emus. Australian Natural History 14, 225–229.
Davies, S. J. J. F. (1976). Studies of the flowering season and fruit production of some arid zone shrubs and trees in western Australia. Journal of Ecology 64, 665–687.
| Studies of the flowering season and fruit production of some arid zone shrubs and trees in western Australia.CrossRef |
Davies, S. J. J. F. (1978a). The food of Emus. Australian Journal of Ecology 3, 411–422.
| The food of Emus.CrossRef |
Davies, S. J. J. F. (1978b). Predicting Emu movements in Western Australia. Australian Vertebrate Pest Conference 1978 – Working Papers 78, 85–90.
Davies, S. J. J. F. (1984). Nomadism in response to desert conditions in Australia. Journal of Arid Environments 7, 183–193.
Davies, S. J. J. F. (2002). ‘Ratites and Tinamous.’ (Oxford University Press: Oxford, UK.)
Davies, S. J. J. F., Beck, M. W. R., and Kruiskamp, J. P. (1971). The results of banding 154 Emus in Western Australia. CSIRO Wildlife Research 16, 77–79.
| The results of banding 154 Emus in Western Australia.CrossRef |
Dawson, T. J., Read, D., Russell, E. M., and Heard, R. M. (1984). Seasonal variation in daily activity patterns, water relations and diet of Emus. Emu 84, 93–102.
| Seasonal variation in daily activity patterns, water relations and diet of Emus.CrossRef |
Day, R. W., and Quinn, G. P. (1989). Comparisons of treatments after an analysis of variance in ecology. Ecological Monographs 59, 433–463.
| Comparisons of treatments after an analysis of variance in ecology.CrossRef |
Fox, G. A. (2000). Failure time analysis: studying times-to-events and rates at which events occur. In ‘Design and Analysis of Ecological Experiments’. 2nd edn. (Eds S. Scheiner and J. Gurevitch.) pp. 253–289. (Oxford University Press: Oxford, UK.)
Grant, W. J. R., and Buttrose, M. S. (1978). Santalum fruit. Domestication of the quandong, Santalum acuminatum (R.Br.) A.DC. Australian Plants 9, 316–318.
Guimarães, P. R., Galetti, M., and Jordano, P. (2008). Seed dispersal anachronisms: rethinking the fruits extinct megafauna ate. Plos One 3, e1745.
| Seed dispersal anachronisms: rethinking the fruits extinct megafauna ate.CrossRef |
Herd, R. M., and Dawson, T. J. (1984). Fiber digestion in the Emu, Dromaius novaehollandiae, a large bird with a simple gut and high rates of passage. Physiological Zoology 57, 70–84.
Higgins, S. I., Nathan, R., and Cain, M. L. (2003). Are long-distance dispersal events in plants usually caused by nonstandard means of dispersal? Ecology 84, 1945–1956.
| Are long-distance dispersal events in plants usually caused by nonstandard means of dispersal?CrossRef |
Howe, H. F., and Smallwood, J. (1982). Ecology of seed dispersal. Annual Review of Ecology and Systematics 13, 201–228.
| Ecology of seed dispersal.CrossRef |
Long, J. L. (1965). Weights, measurements and food of the Emu in the northern wheatbelt of Western Australia. Emu 64, 514–524.
Loveys, B. R., and Jusaitis, M. (1994). Stimulation of germination of quandong (Santalum acuminatum) and other Australian native plant seeds. Australian Journal of Botany 42, 565–574.
| Stimulation of germination of quandong (Santalum acuminatum) and other Australian native plant seeds.CrossRef |
McGrath, R. J., and Bass, D. (1999). Seed dispersal by Emus on the New South Wales north-east coast. Emu 99, 248–252.
| Seed dispersal by Emus on the New South Wales north-east coast.CrossRef |
Mott, J. J., and Groves, R. H. (1981). Germination strategies. In ‘The Biology of Australian Plants’. (Eds J. S. Pate and A. J. McComb.) pp. 307–341. (University of Western Australia Press: Perth.)
Murdoch, A. J., and Ellis, R. H. (2000). Dormancy, viability and longevity. In ‘Seeds – The Ecology of Regeneration in Plant Communities’. 2nd edn. (Ed. M. Fenner.) pp. 183–214. (CABI Publishing: Wallingford, UK.)
Neilson, R. P., Pitelka, L. F., Solomon, A. M., Nathan, R., Midgley, G. F., Fragoso, J. M. V., Lischke, H., and Thompson, K. (2005). Forecasting regional to global plant migration in response to climate change. Bioscience 55, 749–759.
| Forecasting regional to global plant migration in response to climate change.CrossRef |
Noble, J. C. (1975a). Difference in size of Emus on two contrasting diets on the riverine plain of New South Wales. Emu 75, 35–37.
| Difference in size of Emus on two contrasting diets on the riverine plain of New South Wales.CrossRef |
Noble, J. C. (1975b). The effect of Emus (Dromaius novaehollandiae Latham) on the distribution of Nitre Bush (Nitraria billardierei DC.). Journal of Ecology 63, 979–984.
| The effect of Emus (Dromaius novaehollandiae Latham) on the distribution of Nitre Bush (Nitraria billardierei DC.).CrossRef |
Pakeman, R. J., Digneffe, G., and Small, J. L. (2002). Ecological correlates of endozoochory by herbivores. Functional Ecology 16, 296–304.
| Ecological correlates of endozoochory by herbivores.CrossRef |
Quin, B. R. (1984). Food selection and diet in the Emu Dromaius novaehollandiae in the Victoria Valley, Grampians National Park, Victoria. B.Sc.(Hons) Thesis, La Trobe University, Bundoora, Vic.
Quin, B. R. (1996). Diet and habitat of Emus Dromaius novaehollandiae in the Grampians Ranges, south-western Victoria. Emu 96, 114–122.
| Diet and habitat of Emus Dromaius novaehollandiae in the Grampians Ranges, south-western Victoria.CrossRef |
Richmond, G. S., and Chinnock, R. J. (1994). Seed-germination of the Australian desert shrub Eremophila (Myoporaceae). Botanical Review 60, 483–503.
| Seed-germination of the Australian desert shrub Eremophila (Myoporaceae).CrossRef |
Richmond, G. S., and Ghisalberti, E. L. (1994). Seed dormancy and germination mechanisms in Eremophila (Myoporaceae). Australian Journal of Botany 42, 705–715.
| Seed dormancy and germination mechanisms in Eremophila (Myoporaceae).CrossRef |
Robertson, A. W., Trass, A., Ladley, J. J., and Kelly, D. (2006). Assessing the benefits of frugivory for seed germination: the importance of the deinhibition effect. Functional Ecology 20, 58–66.
| Assessing the benefits of frugivory for seed germination: the importance of the deinhibition effect.CrossRef |
Rogers, R. W., Butler, D., and Carnell, J. (1993). Dispersal of germinable seeds by Emus in semi-arid Queensland. Emu 93, 132–134.
Schoener, T. W. (1971). Theory of feeding strategies. Annual Review of Ecology and Systematics 2, 369–404.
| Theory of feeding strategies.CrossRef |
Sokal, R. R., and Rohlf, F. J. (1995). ‘Biometry.’ 3rd edn. (Freeman: New York.)
Struhsaker, T. (1998). Zanzibar’s endangered Red Colobus Monkeys. National Geographic 194, 72–81.
Sweedman, L., and Merritt, D. (2006). ‘Australian seeds. A guide to their collection, identification and biology.’ (CSIRO Publishing: Melbourne.)
Thomas, C. D., Cameron, A., Green, R. E., Bakkenes, M., Beaumont, L. J., Collingham, Y. C., Erasmus, B. F. N., de Siqueira, M. F., Grainger, A., Hannah, L., Hughes, L., Huntley, B., van Jaarsveld, A. S., Midgley, G. F., Miles, L., Ortega-Huerta, M. A., Peterson, A. T., Phillips, O. L., and Williams, S. E. (2004). Extinction risk from climate change. Nature 427, 145–148.
| Extinction risk from climate change.CrossRef | 1:CAS:528:DC%2BD2cXhtFOgtQ%3D%3D&md5=66ae8ac8b5e4bbde1716aca510e43ed8CAS |
Trakhtenbrot, A., Nathan, R., Perry, G., and Richardson, D. M. (2005). The importance of long-distance dispersal in biodiversity conservation. Diversity & Distributions 11, 173–181.
| The importance of long-distance dispersal in biodiversity conservation.CrossRef |
Traveset, A., Robertson, A. W., and Rodríguez–Pérez, J. (2007). A review on the role of endozoochory in seed germination. In ‘Seed Dispersal: Theory and its Application in a Changing World’. (Eds A. Dennis, R. Green, E. Schupp and D. Westcott.) pp. 78–103. (CABI Publishing: Norfolk, UK.)
van der Pijl, L. (1982). ‘Principles of Dispersal in Higher Plants.’ 3rd edn. (Springer–Verlag: Berlin.)
Wenny, D. G. (2001). Advantages of seed dispersal: a re-evaluation of directed dispersal. Evolutionary Ecology Research 3, 51–74.
Westbrooke, M. E., Miller, J. D., and Kerr, M. K. C. (1998). Vegetation of the Scotia 1:100,000 map sheet, western New South Wales. Cunninghamia 5, 665–684.
Williams, D. A. (1982). Extra-binomial variation in logistic linear models. Applied Statistics 31, 144–148.
| Extra-binomial variation in logistic linear models.CrossRef |
Willson, M. F. (1989). Gut retention times of experimental pseudoseeds by Emus. Biotropica 21, 210–213.
| Gut retention times of experimental pseudoseeds by Emus.CrossRef |
Wings, O. (2007). A review of gastrolith function with implications for fossil vertebrates and a revised classification. Acta Palaeontologica Polonica 52, 1–16.
Woodall, G. S. (2004). Cracking the woody endocarp of Santalum spicatum nuts by wetting and rapid drying improves germination. Australian Journal of Botany 52, 163–169.
| Cracking the woody endocarp of Santalum spicatum nuts by wetting and rapid drying improves germination.CrossRef |