Threatened Species and threatened ecological communities
Advice to the Minister for the Environment and Heritage from the Threatened Species Scientific Committee (TSSC) on Amendments to the list of Threatened Species under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act)
Macropus giganteus tasmaniensis (Forester Kangaroo).
Macropus giganteus tasmaniensis is recognised as the Tasmanian subspecies of the Eastern Grey Kangaroo, Macropus giganteus, which is widespread throughout the eastern Australian mainland. The subspecies status of the Forester Kangaroo is based on differences in its skull and coat from the mainland population and its isolation in Tasmania for at least the last 10 000 to 15 000 years. Studies indicate that there is less than 1% difference in the mitochondrial DNA between the mainland Eastern Grey Kangaroo and the Forester Kangaroo.
The Forester Kangaroo is the largest of Tasmania's marsupials. A male Forester Kangaroo can reach over two metres in height when fully upright and can weigh over 60kg. Their coat colour varies from light brownish grey to grey. They are social animals often seen in family groups of three or more and may occur in groups of more than ten. Forester Kangaroos reach breeding age at approximately 2-3 years, and can live for over ten years. Forester Kangaroos feed on grasses, herbs and forbs and their preferred habitat is dry sclerophyll forest with open grassland clearings.
The Forester Kangaroo is a geographically isolated subspecies of the Eastern Grey Kangaroo. Before European settlement, the Forester Kangaroo occurred over parts of eastern, central and northern Tasmania. It has contracted in range since that time and is currently considered to be restricted to north eastern Tasmania and small areas in the Tasmanian Midlands, occurring in the flatter and drier areas in the eastern half of the state below 1000 metres.
Forester Kangaroos now occur in three core areas: two in the Midlands area of Tasmania (Ross and Nile areas) and one in the north east corner of Tasmania. In addition, there are four locations in Tasmania where Forester Kangaroo, following live trapping in the 1970s, have been relocated. They include two island locations (Maria Island, Three Hummock Island) and two locations on the Tasmanian mainland (Kempton and Narawntapu National Park (formerly Asbestos Range)).
Most of the Forester Kangaroos' current range occurs on private land. Traditionally conflicts have occurred, and continue to occur, with agricultural landholders in areas where Forester Kangaroos are implicated in the damage of fence lines and in feeding on crops and improved pastures in competition with domestic stock. Since the late 1970s, Forester Kangaroos have been culled under state Crop Protection Permits issued by the Tasmanian Director of Parks and Wildlife.
The Forester Kangaroo is not listed under the Tasmanian Threatened Species Protection Act 1995. The Forester Kangaroo is classified as 'protected native wildlife' under the Tasmanian Nature Conservation Act 2002.
TSSC judges the Forester Kangaroo to be ineligible for listing under the EPBC Act. The justification against the criteria is as follows:
There have been three state management plans for the Forester Kangaroo, published in 1976, 1988 and 2000 respectively and a number of key activities have been undertaken for the Forester Kangaroo. It has been suggested, that collectively, these actions make up a specific conservation program for the Forester Kangaroo:
It is arguable to what degree these measures actually constitute a specific conservation program for the subspecies. The recent management plan, population monitoring and culling processes can be considered to be part of general landscape management programs conducted by state wildlife authorities to maintain and manage native species that impact on agriculture or cause other problems in the landscape, with the aim of minimizing the impact while maintaining the native species at a sustainable level. Similar monitoring and culling processes occur on the mainland for the Eastern Grey Kangaroo. It was noted that current population numbers of Forester Kangaroo appear to have stabilised and have actually shown increases since the early 1990s, notably in the core population areas in the Tasmanian Midlands.
As a National Park, Mount William National Park would be currently managed for a number of conservation values, one of these being the Forester Kangaroo. It is considered that it is not appropriate to view declaration of the National Park as a specific conservation program for the Forester Kangaroo.
Relocation activities ceased in the late 1970s and only four translocated populations remain. It is not clear to what extent these remaining translocated populations are currently considered to be a specific conservation program for the species. Limited culling continues to occur in island populations of Forester Kangaroo in order to combat over-population and disease.
In summary, the Forester Kangaroo does not appear to be clearly the focus of a current conservation program aimed at the recovery of the species.
There is little quantitative information or analysis available on the likely level of impact on the conservation status of the Forester Kangaroo that would occur if current management activities ceased, and, in particular, no information on how the Forester Kangaroo would become eligible to be listed as threatened under the EPBC Act within the next five years.
It would need to be demonstrated that the level of impact of threats to the Forester Kangaroo would increase within the next five years and that this would have such an impact on population numbers of Forester Kangaroo that it would qualify for listing as a threatened species within this time period. Suggested threats to the Forester Kangaroo include: habitat loss and degradation (clearing of forest on private land), culling (legal and illegal), competition with introduced herbivores (stock and other animals), overstocking of grasslands, 1080 poisoned baiting, disease, road deaths, fences, and climate change.
The level of impact that many of these threatening processes have on the Forester Kangaroo is unclear and despite threats being identified to the Forester Kangaroo, the overall population trend, particularly since the early 1990s, is increasing. For instance the impact of fences and road deaths on the Forester Kangaroo appears to be minimal. Disease appears to only be a factor in managing island populations that have become overpopulated. Clearing has largely ceased in the Midlands.
The Forester Kangaroo has been culled since 1976 under permit. Since 2000, approximately 600 Forester Kangaroos have been culled each year in the Midlands population and 60 in the north east population. Culling also occurs in at least one of the translocation populations. It is claimed that degradation of pasture in Mount William National Park (a former farm) has led to the Forester Kangaroo moving to adjoining private lands and the subsequent need to cull this Kangaroo under permit on these lands. If limited strategic culling was removed, the overall population is likely to increase further and while this may lead to an increase in illegal culling activities, it is unlikely that the species would become threatened within five years.
The Forester Kangaroo has not undergone a recent decline in numbers (within the last three generations) nor is it undergoing a continuing decline, or is it likely to in the foreseeable future. While it is difficult to determine the exact level of impact that cessation of current management measures would have on the subspecies, many measures are unlikely to cease in the short to medium term as they are fundamental to general landscape management programs. Even if they did, it is likely, on the balance of probabilities, that the Forester Kangaroo would not qualify for listing in either the Critically Endangered, Endangered or Vulnerable categories under the Act within the next five years.
In summary, current management measures for the Forester Kangaroo can not be clearly regarded as constituting a specific conservation program for the subspecies, and even if they did, the subspecies is not likely to be eligible for listing as a threatened species within five years should they cease.
Therefore the species is not eligible for listing under this criterion.
Historical trends and threats: The Forester Kangaroo has undergone a reduction of at least 90% in range since European settlement. Little is known regarding the actual rate of historical decline in population numbers since European settlement but it is considered that major declines related to the arrival of white settlers in Tasmania in the early 1800s and occurred due to shooting for human consumption and dog meat. The loss and fragmentation of habitat due to clearing of land for agriculture following expansion of the pastoral industry in the 1820's led to open woodlands with native grasslands, the preferred habitat of the Forester Kangaroo, being used for sheep and cattle grazing. Much of the historical reduction in range occurred before the 1970s as by that time broadscale shooting of Forester Kangaroo has ceased along with broadscale clearing of Forester Kangaroo habitat.
Recent threats: There are claims that a number of threats are currently impacting on the Forester Kangaroo including: habitat loss and degradation (specifically clearing of forest on private land), direct culling of Kangaroos (legal and illegal), competition with introduced herbivores (stock and other introduced animals), overstocking of grasslands, 1080 poisoned baiting, disease, road deaths, fences, and climate change.
The level of impact of these claimed threats is either not clear or minimal. For example, the strength of 1080 poison baits is usually not of sufficient dosage to kill Forester Kangaroos and deaths attributable to roads and fences are considered to be minimal.
Recent population trends: In the 1980s, regular monitoring of the population began. There were some declines in numbers in the 1980s, however, since the early 1990s the overall population has been increasing with the exception of some local declines. Currently the total population of Forester Kangaroo is estimated at approximately 26 000 individuals. Of the 26 000, it is estimated that 30% are yearlings. Therefore the number of mature individuals is no more than 18 200.The north east population, with approximately 2000 individuals, represents less than 8% of the total Forester Kangaroo population.
Due to conflict with agricultural practices, the Forester Kangaroo has been culled since 1976 under permit. Since 2000, approximately 600 Forester Kangaroos have been culled each year in the Midlands population and 60 in the north east population.
The north east Tasmanian population is the only core population where there is claimed to have been a recent and ongoing decline in kangaroo numbers. It is claimed the decline is due to clearing of open forest and heathland for agriculture and culling activities (both legal and illegal). There are claims that degradation of pasture in Mount William National Park (a former farm) has led to the Forester Kangaroo moving from the National Park to adjoining private lands and its subsequent culling under permit. Following surveys undertaken in 2002 this population was estimated to contain approximately 1400 mature individuals (both within the national park and adjoining private land). Some experts consider numbers to be relatively stable in the Mount William National Park but there are concerns about a declining population on adjoining private lands.
It is acknowledged that there has been an increase in population numbers occurring in both the Ross and Nile areas (Midlands region). This region represents by far the most significant percentage of the total Forester Kangaroo population. Both the Ross and Nile core populations are considered to be secure at present, with numbers actually increasing during the 1990s. These areas showed some decline in the 1980s, but populations numbers have been restored to the 1980 level in the Ross area and exceed those of 1980 in the Nile area (in 1999 they were 35% higher).
Relocated populations occur at Maria Island (45 introduced between 1969 to 1971, estimated at 2000 in 1985, currently estimated at 1000), Three Hummock Island (12 introduced in 1975, currently estimated at 400-600), Narawntapu National Park (by 1987 estimated at 200, currently estimated at 50-100), and Kempton (264 animals were released here between 1971-74, currently estimated to be below 200 individuals).
While it is acknowledged that there has been a significant decrease in the geographic distribution of the Forester Kangaroo since European settlement and that from this a significant population size reduction can be suspected to have occurred, the key threatening processes considered to be responsible for this historical decline have slowed considerably or have ceased and the total population is considered to have stabilised within the last three generations . Core populations, in both the Nile and Ross areas, have shown population increases since 1990 and the overall trend in population figures for the Forester Kangaroo has been upward.
Therefore, the species is not eligible for listing under this criterion.
The Forester Kangaroo is now considered to inhabit about 10% of its pre-European range (which was estimated at 40% of Tasmania) and is known from three core population areas (i.e. the Ross and Nile areas in the Tasmanian Midlands and the north east in, and adjacent to, Mount William National Park) with an estimated area of occupancy of 1400km2.
The habitat of the Forester Kangaroo has undergone fragmentation and the subspecies now occurs in a greatly reduced number of locations within Tasmania. The Forester Kangaroo population appears to have stabilised and is not subject to a continuing decline nor is there evidence of extreme fluctuations in population numbers.
There is insufficient justification that the geographic distribution of the Forester Kangaroo is precarious for the survival of the species. It is considered that the remaining habitat is not severely fragmented, the population still exists in a number of locations, and there is neither a continuing decline or evidence of extreme fluctuations in population numbers. The population size of the Forester Kangaroo has stabilised, though there have been some localised decline in the north east.
Therefore, the species is not eligible for listing under this criterion.
The total population size of the Forester Kangaroo is estimated to be approximately 26 000 individuals. Thirty percent of the population are considered to be yearlings. The number of mature individuals is therefore approximately no less than 18 200 (i.e. greater than 10 000) and it is considered that the population has stabilised (see Criteria 1 & 2).
Therefore, the species is not eligible for listing under this criterion.
The estimated total population size of Forester Kangaroo is approximately 26 000 individuals. 30% are considered to be yearlings. The number of mature individuals is approximately no less than 18 200 (i.e. greater than 10 000). The estimated total number of mature individuals is not low, nor does the Forester Kangaroo population have a sufficiently restricted area of occupancy to qualify under this criterion.
Therefore, the species is not eligible for listing under this criterion.
It has been suggested that the probability of extinction in the wild for the Forester Kangaroo is at least 10% in the medium term (i.e. within the next 100 years).
It is unclear what quantitative methods were used or what model was employed in deriving this result. No data was presented to substantiate this claim, nor were the assumptions on which it was based presented. There is no indication that a population viability analysis, or similar analysis, has been undertaken to support this finding.
While a number of threatening processes are identified, many of those thought to have caused the historical decline in the subspecies have ceased. Those currently operating are considered to be having negligible impact and population numbers are showing evidence of recent increases, notably in the Tasmanian Midlands core population areas. The subspecies is actively managed to ensure that population levels remain viable. While it is acknowledged that the impacts of threats are likely to be occurring on the north east population, this is not considered to be significant across the total population, and not sufficient to justify listing under this criterion.
The Committee notes that, since the 1990s the overall population trend for the Forester Kangaroo has been upward and that there is little evidence substantiating a 10% probability of extinction in the next 100 years.
There is insufficient justification against this criterion. Therefore, the species is not eligible for listing under this criterion.
The Forester Kangaroo has been subject to, and continues to be subject to, a number of management measures that are part of general landscape management conducted by state wildlife authorities to maintain and manage the population at a sustainable level. The Forester Kangaroo is primarily managed to ensure sustainable population levels and to mitigate the impacts of kangaroo numbers on agricultural enterprises. This, in itself, is not considered to constitute a specific conservation program for the Forester Kangaroo.
In addition, even if these measures did constitute a specific conservation program, the Forester Kangaroo would, on the balance of probabilities, not be eligible for listing as either Critically Endangered, Endangered or Vulnerable under the Act within the next five years should such measures cease. It is further noted that it is extremely unlikely that current management activities would cease within this time period.
The Forester Kangaroo, while having suffered a historical decline, much of which seems to have occurred in the 1800s and early 1900s, such that it is now estimated to occupy approximately 10% of its pre-European range, is not subject to a continuing decline, nor has it undergone a recent decline (i.e. within the last three generations), and nor is it likely to in the foreseeable future under current circumstances. The Forester Kangaroo is being actively managed to ensure its population numbers remain stable and it is evident that identified threatening processes are not impacting sufficiently on population numbers to cause an overall decline in numbers. While there may have been localised reductions in some locations, these are not significant across the entire population, which has increased in number since the early 1990s.
In addition to its consideration of the Forester Kangaroo for listing under the Conservation Dependent category, the Committee also concluded that the Forester Kangaroo was not eligible for listing as either a Critically Endangered, Endangered or Vulnerable species at this time.
TSSC recommends that the subspecies Macropus giganteus tasmaniensis (Forester Kangaroo) is not eligible for inclusion in any category of the list referred to in section 178 of the EPBC Act.
Barker, R.D. and Caughley, G. (1990). Distribution and abundance of kangaroos (Marsupialia: Macropodidae) at the time of European contact: Tasmania. Australian Mammalogy 13:157-166.
Hocking, G.J. and Dreissen, M.M. (1996). Mammals of Northeast Tasmania. Records of the Queen Victoria Museum 103:163-169.
Kirsch, J.A.W. and Poole, W.E. (1972). Taxonomy and Distribution of Grey Kangaroos Macropus giganteus (Shaw) and Macropus fuliginosus (Desmarest), and their subspecies (Marsupialia: macropodidae). Australian Journal of Zoology 20:315-339.
Tanner, Z. and Hocking, G.J. (2001). Status and Management of the Forester Kangaroo in Tasmania, 2000. Nature Conservation Report 2001/02. Department of Primary Industries, Water and Environment.
Wapstra, J.E. (1976). Forester Kangaroo in Tasmania: Status and Management 1976. Wildlife Division Technical Report 76/1. National Parks and Wildlife Service, Tasmania.