Management of kangaroos in Australia continues to be problematic at a number of levels. Overabundance affects other biodiversity, poses a threat to the conservation or restoration of native vegetation and damages sustainability of primary production. Millions of kangaroos are starving due to drought which is an animal welfare disaster and a national disgrace.
Avoiding boom and bust cycles is a challenge for wildlife and land managers, agricultural agencies, regulators and industry. It also has significant benefits for rural communities, landscape health, food security and waste.
Under what currently passes for management graziers desperate to ‘deal with pests’ are increasingly using control methods that have poor animal welfare outcomes. Amateur shooting and vermin exclusion fences are erected around clusters of properties to reduce unprofitable grazing pressure.
In 2019 two symposia seek a dialogue to address these issues. The first symposium held at the Australian Rangeland Society Biennial Conference in September 2019 focused on kangaroos on lands in primary production. It discussed how imprecise management goals, diverse legislative approaches across jurisdictions, disconnected culling policies even in the one jurisdiction, inadequate application of animal welfare codes and poor market support and product description result in bad outcomes for the welfare of individual kangaroos, the natural resource base on which they depend, land managers, industry participants and eventually the whole kangaroo population.
The second at the ESA in Launceston in November 2019 focuses on kangaroo ecology and population biology. It aims to highlight several case studies where these threats have been measured and to showcase examples of how such risks can be managed.
The output of both symposia will be published in a special edition of Ecological Management and Restoration sponsored by the NSW Kangaroo Management Task Force. It will include messages for policy makers, politicians, international interests and the media plus a statement by concerned scientists which will be available for endorsement by organisations. In its draft form the statement recommends multi-stakeholder collaboration to prepare a National Kangaroo Conservation Strategy.
The proposed Strategy development process would build on existing regional initiatives, include both State and Federal governments, and take steps to prevent perverse cycles from re-establishing when the current drought breaks. The outcome would be reformed management of kangaroos, improved animal welfare and enhanced environmental and agricultural sustainability.

Regulation of macropod populations leading to vegetation change has been proposed as a benefit of reintroducing dingoes into Australian rangelands. The relationship between macropods, vegetation and environmental influences on changes in floristics and structure of herbaceous understorey were studied in temperate grassy woodlands of the New England Tablelands Bioregion, Australia. The aim was to determine whether these ecosystems are more influenced by top-down (herbivory) or bottom-up (environmental) processes. Composition, cover and biomass of vegetation were compared in five pairs of fenced and unfenced experimental plots in two grassy communities, forest grassy dells and derived open grasslands. Macropod grazing density was estimated with time-lapse camera-trapping on each unfenced plot, and environmental variables were also recorded at each plot. Five vegetation surveys were conducted over 2.75 years and analysed in a before-after-control-impact (BACI) framework using univariate and multivariate analyses to identify the response of the vegetation and the drivers of any change. Species cover and diversity increased significantly in both treatments and communities as did the total biomass of dells in both treatments. Dominant and subdominant species remained stable in both treatments and communities despite biomass and cover increases. Macropod grazing supressed biomass increase and increased taxa richness in dells but did not influence the changes in floristics or structure in either community. Fluctuations in biomass and cover and associated shifts in evenness and diversity did not induce a change in vegetation state. The vegetation in this study was more influenced by environmental processes than herbivory, at least in the short term.

Eastern Grey Kangaroos are managed annually across the ACT’s urban reserve network to protect important grassy ecosystems from the impacts of under- or overgrazing. The number of kangaroos to be removed from individual ‘kangaroo management units’ each year is determined based on ecological models which consider functional response curves for the grey kangaroos in a temperate environment, and predictions of pasture growth based on historic weather patterns.
In 2018, an expert workshop was held in Canberra to identify potential improvements to the program based on newly available ecological research. Improvements in the understanding of grassy habitat requirements for reptile, bird and plant species firstly enabled the identification of grass community specific ‘safe operating environments’ as a target for grassy habitat structure. An improved understanding of kangaroo grazing behaviour under different grass structural conditions also enabled identification of scenarios where kangaroo grazing should, or should not, be considered as a tool for effective grassy habitat modification. Combined, this new research enabled kangaroo culling decisions to have improved sensitivity to both current grassy habitat condition (and hence food availability), and the overall conservation objectives for the management unit.
These modifications have since been implemented as part of an updated adaptive management framework for conservation culling in the ACT, and better enable kangaroo management to become part of an integrated approach to grassy layer management at the landscape scale.

We report on a new quantitative review of 50 years of kangaroo population monitoring and management in Victoria's mallee parks. The management program faltered into existence in the 1980s against strong public opposition. The program's motivation was inseparable land degradation and animal welfare concerns: poor vegetation condition and regeneration failure on the one hand, and the repeated instances of mass kangaroo die-off caused by food shortages in dry periods on the other. Population control is considered necessary because the carrying capacity for kangaroos greatly benefited from an increase in pasture availability due to colonial expansion and the absence of hunting and predation. Nonetheless the population control measures are controversial, and expensive to maintain, and Parks Victoria has a long history of research collaboration seeking the most cost-effective ecological outcome with the destruction of as few kangaroos as possible. We synthesise the accumulated population and control data, and review the potential to unify monitoring and control efforts and improve the precision of estimates via removal sampling. We found that the removal sampling model contained a fundamental mis-step that had flattered its simulated performance. The options for park managers to implement more cost effective monitoring and control are limited by fundamental uncertainty about kangaroo population dynamics, and the link between kangaroo control (the action) and regeneration of semi-arid woodlands (the objective) given other herbivores.

The endangered semi-arid Buloke (Allocasuarina luehmannii) Woodlands of south-eastern Australia are threatened by ongoing grazing. Western grey kangaroos (Macropus fuliginosus) are thought to switch from grassy forage to browse, such as tree seedlings, when grass biomass is low. Managers are keen to use forage availability to inform kangaroo management decisions and to refine cull targets. Remote sensing allows for frequent monitoring over a large area, capturing the changes in grass biomass over the landscape and through time. Generalised Linear Mixed Models (GLMMs) were used to describe relationships between biomass data collected over 6 seasons, remote sensing signals, and environmental variables comprising soil moisture, overstorey canopy type, and dominant understorey vegetation. Several vegetation indices and Tasseled Cap transformation bands were compared for their usefulness in modelling biomass in this semi-arid region; results showed that the Normalized Difference Moisture Index (NDMI) performed best overall. Information on forage availability will enable managers to anticipate a decline in biomass to levels where high kangaroo numbers may threaten Buloke regeneration, with the aim of promoting the regeneration of this endangered Woodland Community.

This paper brings into stark focus the reality of managing native animal populations on a grazing property in western NSW when impacted by severe drought in 2018. The property is destocked, feral animals are present (pigs and goats), large dams are almost all dry and there is no feed. This is a property which in the last 10 years has been run on principles of conservative land management, soil conservation and low stocking rates. This, along with the co-existence of native wildlife and feral animals. Feral animals can be culled. Kangaroos are protected. But when drought hits they suffer the most excruciating deaths:
“They die hard and are doing it in their tens of thousands. I hope you understand.”
Appropriate management strategies must be developed to enable the co-existence of wildlife with conservation grazing and land management practices. All Australians are equally responsible for the well-being and management of our native animals. Currently this is solely the responsibility and cost of the farmer.

A regionally significant population of black wallabies (Wallabia bicolor) has been monitored at Royal Botanic Gardens Cranbourne since 2001. Within one of the oldest predator-proof exclosures in Australia, and partly as a consequence of ongoing predator control, the population began to grow exponentially: increasing from around 1 individual /km2 to more than 65/km2 in less than a decade. While there were several potentially positive outcomes from increased wallaby density, the population growth was unsustainable and threatened other biodiversity values at the site. However, options to control population growth rates were fraught with difficulties and required some “outside the square” thinking. Since 2013 a number of passive strategies, including the development of selective fencing, have been implemented to attempt to stem population growth and hopefully allow vegetation communities and small mammal habitats to recover.

Studies of the ecology and management of overabundant macropod populations have traditionally focussed on rural areas, with a particular emphasis on the commercial kangaroo industry. However, as regional areas of Australia become increasingly urbanised and large infrastructure projects fragment the landscape, peri-urban kangaroo populations are increasingly coming into conflict with humans. This is especially the case for the eastern grey kangaroo, Macropus giganteus, which is common along the east coast of Australia, coinciding with the highest human population densities. Regional areas along the east coast are rapidly urbanising. Former agricultural land, a preferred habitat of kangaroos, is being converted to residential estates at an unprecedented rate, combined with large transport infrastructure projects. The end result is fragmentation and isolation of kangaroo populations along the coast.

We studied kangaroo populations dynamics, movement patterns and health at four coastal peri-urban sites. Kangaroo densities at these sites are generally increasing, with the exception of sites which have a high incidence of road kill. Kangaroos in these areas have small home ranges (females = 8.1  1.2Ha, n=20; Males = 12.6  4.2Ha, n=10), and at some sites their core activity areas overlap entirely with residential properties. Conflict is frequently reported at these sites, with kangaroo attacks on people generating fear and promoting a culture where land-owners exclude kangaroos from their property using fencing. When this is coupled with a reluctance to cross major roads, kangaroo populations are faced with diminishing habitat, isolation and unsustainable population densities. In some isolated peri-urban reserves kangaroo population densities exceed 500/km2 and are associated with widespread ill-health, including poor body condition, nutritional stress, non-regenerative anaemia and high levels of parasitism. There are no winners at present. Successful co-existence in the future will, at a minimum, require policy changes which necessitate the inclusion of kangaroo management plans as part of infrastructure development applications in high risk areas.

In the absence of predators, large marsupial herbivores, such as the eastern grey kangaroo (Macropus giganteus) can exhibit irruptive population dynamics. Left unchecked, these irruptions typically lead to overabundance issues, particularly in peri-urban parks and reserves, with negative consequences for biodiversity and animal welfare. Current management decisions are usually guided by estimates of population density, but these can be difficult to obtain, inaccurate and inadequate, because long-term data is required to determine the growth trajectory of a population. We used an alternative framework based on density-dependent changes in vital rates and their surrogates to assess potential indicators of population growth trajectory for eastern grey kangaroos. We measured reproductive rate (a vital rate), body condition as a surrogate for reproduction and survival, and adult sex ratio as a surrogate for (sex-biased) survival, We obtained these data from kangaroos culled during two phases of a population irruption: increasing and post-peak decline. When the population was increasing, female reproductive rate (50% breeding) and body condition (Kidney Fat Index = 12.4) were higher, and sex ratio was less female-biased (66% females) than during the post-peak decline (18% breeding; KFI = 2.9; 90% females). Two of these three variables, reproductive rate and adult sex ratio, are readily measured by observation of free-ranging eastern grey kangaroo populations. Additionally, indices of body condition can be assessed from captured animals or carcasses. This framework therefore provides useful indicators of population growth trajectory, which can be used to forecast management issues and initiate timely management actions.

A remotely deliverable, single dose, long-lasting contraceptive could provide an efficient tool for reducing the rate of increase of free-ranging populations of Eastern Grey Kangaroos (Macropus giganteus).
We are evaluating dart delivered administration of GonaCon Immunocontraceptive Vaccine to female Eastern Grey Kangaroos by observing responses over time at the individual and population levels.
Initial trials identified a suitable dart for administering GonaCon intramuscularly. Female kangaroos (n=142) at five sites in the ACT were then treated with a single dose of GonaCon, injected either by hand or by remote dart, or a placebo, to compare the efficacy of the two methods. Population level effects are being investigated by comparing population growth and fecundity between treated (n=3) and untreated (n=7) sites.
In the year following GonaCon treatment, 13.3% of hand-injected and 20.8% of dart-delivered kangaroos produced a young. In the second year, none of the hand-injected and 8% of the dart-delivered kangaroos produced a young. In the two years following placebo treatment, 90% and 88.9% of females produced a young.
Fecundity decreased to between 0% and 22% in treated populations whereas fecundity in untreated populations ranged from 54% to 88%.
Results so far indicate that if long-term efficacy is achieved, dart delivery of GonaCon will be at least 50% more efficient than capture and injection by hand. This approach therefore could provide an efficient and more cost-effective option compared to currently available fertility control methods which require kangaroos to be captured for treatment.