Three species of deer found in Australia’s tropics: Chital (photo Dr Rory Nevard); rusa (photo Harry Nevard); sambar (photo Dr Tim Nevard).
NEWS Tim Nevard
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A recently published article in the peer-reviewed journal Animals has explored ecological and historical factors related to the current unique guild of native and introduced mammalian herbivores in northern Australia. The authors, Dr Peter Murray, an Associate Professor of Wildlife Management at the University of Southern Queensland’s School of Agriculture and Environmental Science and Dr Tim Nevard, an Adjunct Professor at James Cook University’s Cairns Institute (who is also a board member of the Australian Deer Association), found a dearth of supporting evidence to properly inform appropriate sustainable management of deer in Northern Australia, and identified essential research to address significant gaps in our knowledge.
Mean mature bodyweights of the guild of northern tropical Australian native (blue); introduced mammalian herbivores larger than 5 kg (dark green); and deer (light green).
Following the disappearance of Australia’s native megafauna about 46,000 years ago, only one surviving species of native mammalian herbivore has an adult bodyweight approaching 100 kg (the red kangaroo), with all other native herbivorous mammals being mid-sized. All these have continued to utilise the native vegetation on which their much larger former co-inhabitants also foraged. Since the arrival of Europeans and their livestock, over the past 150–200 years the total biomass of introduced domestic and wild herbivores has massively exceeded that of native herbivorous species, with research recently published in Science by Dr Erick Lundgren and his colleagues indicating that the ecological roles of at least some of these animals could be close to that of Australia’s extinct megafauna.
With climate and human-related changes due to fire, drought, flooding, predation and introduced weeds, there are likely to be significant impacts on the ecological roles and populations of our current guild of native and introduced mammalian herbivores. Against this backdrop and given their differing ecological and dietary characteristics, it is unclear what the potential impact of the dispersal of deer species could have in northern Australia. The review therefore focussed on what research exists against which the potential impacts of range expansion of the three deer species currently found in northern Australia could be adequately assessed and managed.
“It is unclear what the potential impact of the dispersal of deer species could have in northern Australia.”
The principal author of the review, Dr Murray, indicated that “Northern Australia has a unique community of native and introduced mammal herbivores where there is only one native herbivore with an adult bodyweight of about 100 kg; all other large herbivorous species, weighing up to 1,000 kg, are introduced species. With climate and anthropogenically related changes due to fire, drought, flooding, predation, introduced plants and introduced animals means that this landscape is undergoing significant change. With different ecological and dietary characteristics, it is difficult to predict the potential impact and possible benefits that chital, rusa and sambar could have, if dispersal of these species occurs in northern Australia, given a lack of information to inform appropriate management of these species, research is required.”
Dr Nevard went on to say that “the review identified that there are clear gaps in published research on how deer coexist or interact with domestic and free-living populations of introduced and native herbivores in tropical Australia’s savannas. We strongly urge that research focusing on the degree of ecological separation of deer from native and introduced herbivores be undertaken to address these gaps.”
Although the review noted some degree of ecological separation amongst northern Australia’s mammalian herbivore guild, it identified clear gaps in the published research identifying how deer coexist or interact with domestic and free-living populations of introduced and native herbivores. Before appropriate informed decisions on the sustainable management of deer in northern Australia can be therefore made, significant additional objective structured scientific investigation in the following areas is essential:
What are the changes to plant community structure initiated or progressed by deer (grazing, browsing, the removal of seedlings, tree rubbing, etc.) in different habitats; where populations of native and introduced herbivores are also found?
Do deer compete with or negatively impact native herbivores or displace other introduced species?
How frequently are deer are predated by dingoes/wild dogs and crocodiles and is this predation a regulator of populations?
Do deer have their populations regulated by current climatic conditions and will climate change, water sources, fire, floods and drought be important regulators of deer populations in the future?
What are the roles of deer and other introduced herbivores as dispersers of plant seeds or spores through ingestion and distribution through their faeces?
Do deer have impacts on smaller (<5 kg) native vertebrates and the wide range of invertebrates sharing the same habitats?
What is the potential for deer to create local industries for meat, skins, velvet or hunting and how these might be engaged by First Nations people, as currently occurs in the Cobourg/Garig Gunak Barlu National Park in the Northern Territory?
What are the potential roles of deer and other introduced herbivores as reservoirs and vectors for parasites and infectious diseases?
The full article can be accessed at: Murray, P.J. & Nevard, T.D. The Ecological Separation of Deer and Domestic, Feral and Native Mammals in Tropical Northern Australia—A Review. Animals 2024, 14, 1576. https://doi.org/10.3390/ ani14111576
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