Australia is home to roughly 40 to 50 million kangaroos of the four large commercially managed species, though that number swings wildly depending on rainfall and drought cycles. The Australian government conducts aerial surveys each year across the commercial harvest zones, and those counts have dipped below 30 million after severe droughts and climbed above 50 million during extended wet periods. Those headline figures, however, only cover the four species tracked for the commercial harvest and only within designated survey zones, so the true continent-wide total across all kangaroo and wallaby species is almost certainly higher, and harder to pin down than a single number suggests.
Which Species Get Counted
When people cite a national kangaroo population figure, they are almost always talking about the four species monitored under Australia’s commercial kangaroo management programs: the red kangaroo, the eastern grey kangaroo, the western grey kangaroo, and the common wallaroo. These are the largest macropods, the ones most visible across Australia’s rangelands, and the ones most likely to come into contact with pastoralists and their livestock. State wildlife agencies in New South Wales, Queensland, South Australia, and Western Australia fly annual aerial transects to estimate their numbers, then set harvest quotas based on those estimates.
Dozens of other macropod species live across the continent, from small rock-wallabies and pademelons in Queensland’s wet tropics to quokkas on Western Australia’s Rottnest Island. These species are not included in the headline population number, and many of them face conservation challenges that are the opposite of the large kangaroos’ story: habitat loss, predation by foxes and cats, and declining numbers. When researchers talk about kangaroo “overabundance,” they are talking about the big four, not macropods as a group.
How Australia Counts Its Kangaroos
The standard method is strip-transect aerial survey. Light aircraft fly predetermined lines across the landscape at low altitude, and trained observers on each side of the plane count every kangaroo they can see within a fixed strip below. The distances covered are enormous; the survey zones span hundreds of thousands of square kilometres of arid and semi-arid rangeland. Because observers can only spot animals that are visible and not hidden under trees or scrub, correction factors are applied to account for the ones that are missed.
Those correction factors are a significant source of uncertainty. A comparative study that flew the same transects using both thermal cameras and human observers found that the thermal imagery detected about 30% more kangaroos per square kilometre than the human crew did.1Wildlife Research. Estimating kangaroo density by aerial survey: a comparison of thermal cameras with human observers That gap matters when you scale it up across an entire state. If standard surveys systematically undercount by even a modest percentage, the real population could be substantially larger than published estimates. On the other hand, surveys are generally flown during cooler morning hours when kangaroos are more active and visible, which may partially offset the undercounting problem. The bottom line is that every published kangaroo population figure carries a margin of error that is hard to nail down precisely.
Critics of the survey system have pointed out additional concerns. One analysis argued that year-to-year changes in the official estimates sometimes imply biologically implausible growth rates, suggesting that counting variability rather than actual population change may be driving some of the fluctuation. Even in very good conditions, a kangaroo population is unlikely to grow at a rate much above 12% per year, yet official tables have sometimes shown apparent jumps of several hundred percent between consecutive surveys in some zones.2Animal Studies Journal. The Number Game: Counting Kangaroos Whether those jumps reflect real movement of animals into a survey area or statistical noise in the count is an ongoing debate.
Why the Numbers Swing So Dramatically
Rainfall is the single biggest driver of kangaroo population size. In Australia’s arid interior, a few good wet years can transform sparse, dry rangeland into lush grassland, giving kangaroos abundant food and triggering a reproductive boom. Female kangaroos can reproduce quickly under good conditions, and their unusual reproductive biology, including the ability to pause embryonic development and resume it when conditions improve, helps the population respond fast when rain arrives.
Drought reverses the process just as sharply. When feed dries up, kangaroos lose body condition, reproduction slows, and mortality climbs. Poor body condition during drought weakens immune responses and increases susceptibility to infection, contributing to elevated death rates beyond simple starvation.3PubMed Central. The Impacts of Drought on the Health and Demography of Eastern Grey Kangaroos Red kangaroos in particular tend to aggregate in areas where green feed persists, creating local concentrations that can give the impression of abundance even as the total population is crashing.4Journal of Applied Ecology. Spatial patterns of kangaroo density across the South Australian pastoral zone over 26 years: aggregation during drought and suggestions of long distance movement Western grey kangaroos, by contrast, do not show the same drought-driven aggregation pattern, which may reflect differences in mobility and habitat preference between the two species.
This boom-and-bust cycle means that a single population snapshot can be misleading. The national estimate after the severe 2018–2020 drought was dramatically lower than the figure just a few years earlier, and numbers rebounded once widespread rains returned. Anyone quoting a kangaroo population figure without specifying the year and the rainfall context is telling you only part of the story.
The Subpopulation Puzzle
Kangaroo populations are not one giant, well-mixed mass spread evenly across the continent. Research using statistical models to tease apart spatial structure has identified distinct subpopulations of red kangaroos and grey kangaroos within individual states, with the boundaries between groups appearing to follow rainfall gradients running roughly east to west.5Ecological Management & Restoration. Assessing the spatial and temporal organization of Red Kangaroo, Western Grey Kangaroo and Eastern Grey Kangaroo populations in eastern Australia using multivariate autoregressive state‐space models This means that a drought hitting western New South Wales might hammer one subpopulation while another farther east, receiving slightly more rain, holds steady.
Genetic work adds another layer. A study of eastern grey kangaroos in southeast Queensland found clear genetic differentiation between populations separated by relatively short distances, with urbanisation and natural barriers limiting gene flow between groups. Some local populations had very small effective population sizes despite appearing outwardly healthy, and high numbers of unique genetic variants in each region underscored the conservation value of maintaining connectivity between them.6Global Ecology and Conservation. Spatial genetic structure and gene flow of the eastern grey kangaroo (Macropus giganteus), in a rapidly urbanising landscape In northern Australia, the picture is different again: the antilopine wallaroo, whose range is broken by an arid gap in the Gulf Country, showed surprisingly little genetic divergence across that gap, while the common wallaroo, whose range is continuous through the same area, was highly divergent across it.7PubMed Central. Differing impact of a major biogeographic barrier on genetic structure in two large kangaroos from the monsoon tropics of Northern Australia Barriers to movement do not affect every species the same way.
How Humans Inflated the Big Kangaroos
Today’s large kangaroo populations are not entirely “natural” in the sense of reflecting pre-European conditions. The arrival of pastoral agriculture fundamentally reshaped the Australian landscape in ways that favoured the big kangaroo species. Sheep and cattle grazing converted tall tussock grasslands into short, open pastures, which happen to be ideal foraging habitat for red and grey kangaroos. Smaller macropods that depended on dense grass cover for shelter lost out, while the large, open-country kangaroos gained access to better food over a much wider area.8PubMed Central. An ecological comparison of the two arid-zone kangaroos of Australia, and their anomalous prosperity since the introduction of ruminant stock to their environment
Pastoralists also installed tens of thousands of artificial water points, bore-fed dams and troughs, across the rangelands. This opened up vast tracts of country that kangaroos could not previously use because they were too far from water. Interestingly, one field experiment found that fencing off these water points did not reduce kangaroo density or change their distribution in the surrounding area, suggesting that food availability rather than water access is the primary factor determining where kangaroos settle at a local scale.9CSIRO Publishing / Wildlife Research. Fencing artificial waterpoints failed to influence density and distribution of red kangaroos (Macropus rufus) Still, at a landscape scale the cumulative effect of reliable water access has been significant for allowing kangaroos to persist in areas that were previously marginal.
What the Dingo Fence Reveals
Australia’s dingo barrier fence stretches over 5,000 kilometres across the southeast of the continent, originally built to keep dingoes away from sheep country. It also created a continent-scale natural experiment in predator effects on kangaroo populations. On the sheep-farming side where dingoes are rare or absent, kangaroo numbers are consistently higher. On the other side, where dingo populations are healthier, kangaroo abundance is markedly lower.10Journal of Archaeological Science. The effect of a top predator on kangaroo abundance in arid Australia and its implications for archaeological faunal assemblages
The difference is not just in total numbers. Research comparing red kangaroo populations on either side of the fence found that in areas with more dingoes, there were relatively fewer females and juveniles, but the kangaroos that survived were physically larger for their age.11PubMed Central. Differential developmental rates and demographics in Red Kangaroo (Osphranter rufus) populations separated by the dingo barrier fence This is a classic pattern in prey populations under predation pressure: fewer individuals, but each one in better condition because there is less competition for food. The dingo fence effectively demonstrates that removing a top predator inflates kangaroo populations, which then face greater food competition and may cause more damage to vegetation, precisely the dynamic that fuels ongoing debates about kangaroo management.
Kangaroos, Livestock, and the Competition Question
Graziers have long argued that kangaroos compete with their sheep and cattle for pasture, and the science broadly supports this claim, though with important caveats. A large-scale field experiment in arid rangeland tested the interaction directly by running paddocks with sheep only, kangaroos only, and a mixed treatment. Competition between red kangaroos and sheep was intermittent, occurring mainly during periods of drought-related food shortage, when kangaroo densities spiked because animals moved in from surrounding country. During those lean times, sheep in mixed paddocks lost body weight, though their wool production was not significantly affected. The kangaroos themselves showed no detectable drop in condition from the competition.12Australian Journal of Ecology. Competition between red kangaroos (Macropus rufus) and sheep (Ovis aries) in the arid rangelands of Australia
Under severe feed shortage, both kangaroos and livestock concentrate on whatever patches still support nutritious forage, intensifying the overlap in their diets.13Journal of Arid Environments. Competitive interactions in the dietary preference of kangaroos and sheep, cattle and goats in inland Australia This means that competition is not a constant drag on pastoral productivity but a periodic, drought-triggered problem, which is precisely when graziers can least afford it.
Overgrazing in Conservation Reserves
The ecological impact of high kangaroo numbers extends beyond farmland. In semi-arid conservation reserves, where sheep and cattle have been removed, kangaroos sometimes fill the grazing niche and reach densities that damage the vegetation the reserves are meant to protect. Studies in reserves across semi-arid New South Wales found that kangaroo grazing reduced grass cover, decreased plant species richness, depleted soil carbon and phosphorus, and increased soil compaction, all symptoms of overgrazing.14Global Ecology and Conservation. Grazing by over-abundant native herbivores jeopardizes conservation goals in semi-arid reserves Separate work confirmed that kangaroo grazing decreased grass biomass, raised soil density, and reduced the rate at which water could soak into the ground.15Journal of Arid Environments. Impacts of grazing by kangaroos and rabbits on vegetation and soils in a semi-arid conservation reserve
This creates an uncomfortable management dilemma. Conservation reserves are fenced to keep livestock out, but kangaroos are native animals that move freely across fences. Without dingoes to regulate them, and with artificial water and improved pasture nearby, kangaroo numbers inside reserves can climb to levels that undermine the very ecosystems the reserves were established to conserve. Some ecologists have argued that active management of kangaroo numbers inside reserves may be necessary, a position that sits uneasily alongside the broader public sentiment that kangaroos are an iconic species deserving protection.
Kangaroos at the Urban Edge
Australians increasingly encounter kangaroos not on remote pastoral stations but in suburban parks, golf courses, and along highways. Eastern grey kangaroos in particular thrive in the grassy margins of cities and towns, where irrigated sports fields and nature reserves provide year-round food. But urban proximity comes with a heavy cost: vehicle collisions.
In Canberra, rangers collected over 3,300 kangaroo-vehicle collision reports in just 15 months, and the frequency of these collisions has risen steadily over the past three decades as the city has expanded into kangaroo habitat.16Ecological Management & Restoration. Spatio‐temporal analysis of kangaroo–vehicle collisions in Canberra, Australia A tracking study of an urban eastern grey kangaroo population found that vehicle collisions accounted for nearly three-quarters of all deaths, and the population underwent a steep decline as a result. Roads cut through many parts of the kangaroos’ home ranges, exposing them to traffic on a daily basis.17Wildlife Research. Spatial ecology of an urban eastern grey kangaroo (Macropus giganteus) population: local decline driven by kangaroo–vehicle collisions For peri-urban kangaroo populations, road mortality can be a bigger threat than drought or predation.
Toxic Plants and Emerging Health Threats
Disease and poisoning occasionally cause localised mass mortality events that do not register in the national population estimates but can devastate individual populations. In 2014, a mass die-off of eastern grey kangaroos near Wagga Wagga, New South Wales, was linked to ingestion of an introduced grass species that caused liver damage and photosensitisation. Affected kangaroos went blind, sought shade in buildings, and wandered onto roads, leading to large numbers of deaths.18Charles Sturt University Research Output. Mass mortality of Eastern Grey Kangaroos (Macropus giganteus) associated with hepatogenous photosensitisation subsequent to ingestion of Panicum gilvum The broader issue of introduced toxic plants affecting native mammals that have no evolutionary tolerance for them is still poorly documented but appears to be a growing concern.
Blood parasites including piroplasms and trypanosomes have been detected in eastern grey kangaroos during mortality investigations, though the role of these parasites in causing illness remains unclear. One study noted that other factors, such as chronic toxicity from Phalaris grass, likely played a larger role in the mortality event being investigated.19International Journal for Parasitology: Parasites and Wildlife. Tick-borne piroplasms and trypanosomes incidentally detected in eastern grey kangaroos (Macropus giganteus) during a mortality and morbidity event in southern New South Wales, Australia Australia has so far avoided the kind of devastating wildlife diseases, like chronic wasting disease in North American deer, that could reshape kangaroo population dynamics overnight, but the potential is something wildlife managers keep an eye on.
The Commercial Harvest and What It Means for Numbers
Australia permits a commercial harvest of the four main kangaroo species, with annual quotas set by state governments based on the aerial survey estimates. In a typical year, well over a million kangaroos are shot commercially in New South Wales alone, with roughly half taken for the kangaroo meat and skin industry and the rest culled under damage-mitigation permits.2Animal Studies Journal. The Number Game: Counting Kangaroos Nationally, the total annual harvest across all states usually falls between 1.5 and 3 million animals, depending on quotas and market conditions.
Supporters of the harvest argue that it is ecologically sustainable given the population sizes involved, and that without it, kangaroo numbers would climb even higher and cause more environmental damage. Critics counter that the population estimates underpinning the quotas are less reliable than they appear, and that framing kangaroos as pests “in plague proportions” serves the commercial industry more than it reflects ecological reality. The debate is unlikely to be resolved soon, because it rests as much on values and priorities as on population biology. What is clear is that the harvest, whatever its merits, does remove a significant number of animals each year and is one of several factors, along with drought, predation, disease, and vehicle collisions, that shape the national total.
Why a Single Number Is Always Misleading
Asking “how many kangaroos are in Australia” is a bit like asking how full a reservoir is without specifying the season. The answer changes year to year, sometimes by tens of millions of animals. It depends on which species you include, which parts of the country get surveyed, and how much rain fell in the previous couple of years. The published estimates for the four commercial species are the best numbers available, but they apply only to the survey zones, they carry inherent undercounting biases, and they exclude the many smaller macropod species that share the continent. The true total number of kangaroos and their close relatives across all of Australia is genuinely unknown, and given the practical impossibility of surveying every patch of forest, mountain, and coast, it will stay that way.