|Scientific Name:||Phascolarctos cinereus (Goldfuss, 1817)|
Lipurus cinereus Goldfuss, 1817
|Red List Category & Criteria:||Vulnerable A2b+3bce+4bce ver 3.1|
|Assessor(s):||Woinarski, J. & Burbidge, A.A.|
|Contributor(s):||Martin, R., Menkhorst, P., Lunney, D., Gordon, G., Adams-Hosking, C., Dickman, C. & McAlpine, C.|
The conservation status of the Koala has been contested (Melzer et al. 2000; The Senate Environment and Communications References Committee 2011), in part because of uncertainty about relevant population parameters and marked variation in population trends across its large range. The overall rate of decline in population size over the last 18-24 years (=three generations) was estimated at about 28% by the Threatened Species Scientific Committee (2012), with this rate substantially influenced by a severe decline in inland regions most exposed to recent drought. A separate expert elicitation process involving independent estimates (from 15 Koala experts) of population size in every bioregion inhabited by Koalas concluded that the Koala population size reduction or projected reduction over three generations is a mean of 29%, albeit with substantial variation amongst experts in estimation of this rate (McAlpine et al. 2012). Climate change is expected to lead to an increased rate of population reduction over the next 20-30 years, and the impacts of other threats will magnify over this period. Here we consider that the conservation status of the Koala is border-line between Near Threatened and Vulnerable, but we adopt a precautionary assessment given the proximity of the estimated current and projected rate of decline to the threshold, and published assessments of the likelihood of additional and compound impacts due to climate change (Woinarski et al. 2014)
|Previously published Red List assessments:|
|Range Description:||The Koala was formerly common throughout the broad band of forests and woodlands dominated by Eucalyptus spp. extending from north Queensland to the south-eastern corner of mainland South Australia, Australia (Maxwell et al. 1996). Currently it occurs in northeastern, central, and southeastern Queensland with patchy populations in western areas; eastern New South Wales including the coastal strip and highlands of the Great Dividing Range, as well as the western plains and related riparian environments where suitable habitat occurs; Victoria; and southeastern South Australia. Its total geographic range has contracted significantly due to loss of large areas of habitat since European settlement. In Queensland, extent of occurrence and area of occupancy have contracted by about 30% (Gordon et al. 2006).|
The Koala has been introduced to at least 12 islands including: Kangaroo (South Australia, 450,000 ha), French (Victoria, 17,470 ha), Phillip (Victoria, 10,116 ha), and Magnetic (Queensland, 5,200 ha) (Abbott and Burbidge 1995). It has also been introduced within the mainland in the Adelaide Region and along the Murray River (Maxwell et al. 1996).
Native:Australia (New South Wales, Queensland, South Australia, Victoria)
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||There are robust population estimates for some regions, notably the Mulga Lands of southwest Queensland (for which a 2009 estimate is about 12,000 individuals: Seabrook et al. 2011). More broadly, Queensland EPA (2006) estimated the Koala population size in Queensland in 2006 at between 100,000 and 300,000 individuals. In its 2012 listing advice, the Threatened Species Scientific Committee (2012) provided State-based ‘best estimates’ of population size in 2010, tallying to between 347,000 and 518,000 individuals across all States. Some other sources have concluded that the population size is <100,000 individuals (see The Senate Environment and Communications References Committee 2011). A recent expert-based elicitation process provided an aggregated mean estimate of 330,000 individuals across the Koala’s current range (McAlpine et al. 2012), suggesting the number of mature individuals is c. 300,000.|
Population densities are very variable between regions and across time: examples include 1-3 individuals/ha in coastal forests in south-eastern Queensland (Queensland EPA 2006), 0.01/ha in central Queensland (Melzer et al. 2000), 0.006/ha in coastal forests of south-eastern New South Wales (Jurskis and Potter 1997), and >5/ha in forests on Kangaroo Island prior to population control (Masters et al. 2004).
Koala subpopulations may show marked fluctuation, with severe crashes associated with over-browsing (Menkhorst 2004, 2008) and with long periods of low rainfall or episodes of very high temperatures (Gordon et al. 1988, Seabrook et al. 2011).
Gordon et al. (2008) considered the overall direction for population trend for Koalas to be unknown. However, the evidence for overall reduction in population size over the past three generations is compelling, given sustained management to reduce or stabilize population density of the largest South Australian subpopulation, demonstration of major decline in parts of inland Queensland (notably in the Mulga Lands, where population size decreased over recent decades by 80%: Seabrook et al. 2011), and in much of the coastal range of south-eastern Queensland (e.g. 68% decline in the ‘Koala Coast’ region from 1999 to 2010) and New South Wales. However, trends in these regions are not necessarily typical of the broader range, and population trends may also vary between different subpopulations within regions: for example, while most monitored Queensland subpopulations have experienced decline over the last two decades, a low density population at Oakey on the eastern Darling Downs has shown relative stability in population size (McAlpine et al. 2012; G. Gordon pers. comm. 2014). Likewise, in New South Wales, subpopulations in coastal regions have declined (some, including around Eden and Iluka, to extirpation or nearly so), but there are several subpopulations (including Lismore, Campbelltown and Southern Highlands) that are relatively stable.
Regional-level population size and trend estimates were collated by the Threatened Species Scientific Committee (2012), based on information from sites with known population density information (or estimates of number of individuals in subpopulations) and monitoring results, extrapolated to regional scale, and summed over regions, with some sensitivity analysis. These estimates indicate a 20-year (1990-2010) decline in population size nationally of about 28%, with that decline greatest in low rainfall areas of western Queensland exposed to drought conditions. A summary of their interpretation of population status and trends is given in Table 1 in the Supplementary Material. The major uncertainties in these estimates of population trends arise from the wide range of estimates for the size of the Victorian subpopulations, and to the imprecision of extrapolations of limited site-specific data to broader regional trends.
A separate and subsequent independent assessment of population size and trends was provided by McAlpine et al. (2012), based on an expert elicitation process (e.g. McBride et al. 2012) involving 15 experts in Koala ecology and management across the Koala’s range. Although some state-based population size estimates differed from those given by the Threatened Species Scientific Committee, this process reported a remarkably similar estimate of overall decline in population size of 28.6% in three generational periods (over a ‘sliding time window of the past three generations and the future three generations of koala (15-21 years)’), although with very wide bounds around the relevant population size and trend estimates (Table 2 in the Supplementary Material). These wide bounds are indicative of substantial disagreements between experts concerning population size and trends, and the sparse and not necessarily representative monitoring data for some subpopulations. Note also that McAlpine et al. (2012) used a 5-7 year period for generational length, in contrast to the 6-8 year period reported by Phillips (2000).
With respect to eligibility against IUCN criteria, it could be argued that the decline over the last three generations has been driven mainly by the impacts of a severe drought, that has now ceased, and hence that the relevant criterion is A1, for which a decline of >50% in the relevant 20 year time frame would be required for eligibility. However, drought has been only one of many factors driving decline across the Koala’s range. Furthermore, the ability of inland Koala populations to recover from this recent drought is likely to be severely compromised by widespread tree death and the legacy impacts of vegetation clearance which will constrain options for repopulation of now fragmented habitat (Seabrook et al. 2011; Adams-Hosking et al. 2011a,b, 2012). Other threats will continue to cause broad-scale population decline across much of the Koala’s range, and the impacts of at least some of these threats may be expected to be exacerbated by climate change (Adams-Hosking et al. 2011a,b, 2012).
|Current Population Trend:||Decreasing|
|Habitat and Ecology:|
The Koala is an arboreal folivorous marsupial. It occurs in forests and woodlands, typically dominated by eucalyptus species. In inland (semi-arid) portions of its range, it occurs mainly in riparian woodlands (Ellis et al. 2002, Seabrook et al. 2011). Elsewhere distribution may be associated particularly with soil fertility (and hence foliage nutrient content) (Moore and Foley 2000). The Koala has a specialist diet, mostly limited to foliage of Eucalyptus species, with occasional intake of leaves of other plant (mostly Myrtaceous) genera (Martin and Handasyde 1999; Moore and Foley 2000, 2005). At high population densities, Koalas can defoliate preferred tree species, causing tree death and subsequent Koala population crash (Menkhorst 2004, 2008).
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Generation Length (years):||6-8|
|Movement patterns:||Not a Migrant|
|Use and Trade:||Formerly Koala subpopulations were severely depleted by hunting (for furs), with millions killed. This hunting continued up to 1927 in Queensland (Hrdina and Gordon 2004, Gordon and Hrdina 2005, Gordon et al. 2008).|
Current threats to this species include continued habitat destruction, fragmentation, and modification (which makes them vulnerable to predation by dogs, vehicle strikes, and other factors), bushfires, and disease, as well as drought associated mortality in habitat fragments. Public concern for the species is high. There are management problems with many populations; remnant populations living at high densities in isolated patches of habitat are at greatest risk (Martin et al. 2008). Effective management of some of the threats on the mainland could lead to excessive abundance and result in pest problems similar to those occurring on Kangaroo Island and in parts of Victoria.
The overall distribution of Koalas has been reduced since European settlement. This decline was primarily due to disease, bushfires, and widespread habitat destruction in the early decades of the 20th century. Commercial harvesting also took place across the range towards the end of the 19th century and early 20th century (large numbers, running into the millions, were killed for their pelts for a large export industry in Victoria, New South Wales, and Queensland). This was banned in Victoria in the 1890s, and it continued sporadically (and under regulation) in Queensland until 1927 (Hrdina and Gordon 2004). There is no evidence, however, that the early spate of commercial harvesting had any long-term impact on the overall population. Climate change is likely to have severe consequences for this species (Adams-Hosking et al. 2011a,b, 2012).
There is no national recovery plan; however there is a national conservation and management strategy (NRMMC 2009), a recovery plan for the Koala in New South Wales (NSW DECC 2008), a management strategy in Victoria (Menkhorst 2004), and a conservation plan and management program for the Koala in Queensland (Queensland EPA 2006).
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Adams-Hosking, C., Moss, P.T., Rhodes, J.R., Grantham, H.S. and McAlpine, C. 2011. Modelling the potential range of the koala at the last glacial maximum: Future conservation implications. Australian Zoologist 35: 983-990.
Ellis, W.A.H., Melzer, A., Carrick, F.N. and Hasegawa, M. 2002. Tree use, diet and home range of the koala (Phascolarctos cinereus) at Blair Athol, central Queensland. Wildlife Research 29: 303-311.
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|Citation:||Woinarski, J. & Burbidge, A.A. 2016. Phascolarctos cinereus. The IUCN Red List of Threatened Species 2016: e.T16892A21960344.Downloaded on 24 November 2017.|
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