Ornithorhynchus anatinus 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Mammalia Monotremata Ornithorhynchidae

Scientific Name: Ornithorhynchus anatinus (Shaw, 1799)
Common Name(s):
English Platypus, Duck-billed Platypus
French Ornithorynque
Platypus anatinus Shaw, 1799

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2016
Date Assessed: 2014-04-22
Assessor(s): Woinarski, J. & Burbidge, A.A.
Reviewer(s): Hawkins, C.
Contributor(s): Menkhorst, P., Grant, T., Dickman, C., Lunney, D., Serena, M., Gust, N. & Copley, P.
The Platypus has an extensive range and a large population size that precludes eligibility under criteria B, C and D. However, an overall decline can be inferred and projected from information from a small set of monitoring programs and suspected from threats directly affecting this species and its habitat. This decline is inconsistent across its range, and the overall rate of decline is poorly defined, but is likely to approach but not exceed >30% over a 27-36 year (=three generation) period.
Previously published Red List assessments:

Geographic Range [top]

Range Description:The Platypus is endemic to Australia, where it is dependent on rivers, streams, and bodies of freshwater. It is present in eastern Queensland and New South Wales, in eastern, central, and south-western Victoria, throughout Tasmania, and on King Island. An introduced population is established at the western end of Kangaroo Island (Carrick et al. 2008). Its occurrence is reasonably continuous within some catchments, but discontinuous in others (e.g., the Bega River catchment in New South Wales; Lunney et al. 2008), and in many catchments its actual distribution is poorly known. In Victoria, fewer than 200 individuals occupy the Wimmera-Avon River basin (distributed over an area of >2,400,000 ha), and the species appears to have recently become extinct in the neighbouring Avoca River basin (Australian Platypus Conservancy, unpublished data) (T. Grant, S. Munks, F. Carrick, and M. Serena pers. comm. 2014). The species now appears to be extinct also from its former range in the Adelaide Hills and Mount Lofty Ranges in South Australia.
Countries occurrence:
Australia (New South Wales, Queensland, South Australia, Tasmania, Victoria)
Additional data:
Estimated area of occupancy (AOO) - km2:12400Continuing decline in area of occupancy (AOO):Yes
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:1096396
Continuing decline in extent of occurrence (EOO):NoExtreme fluctuations in extent of occurrence (EOO):No
Number of Locations:100Continuing decline in number of locations:Yes
Extreme fluctuations in the number of locations:No
Range Map:Click here to open the map viewer and explore range.

Population [top]


Difficulties in reliably quantifying platypus abundance compromise estimation of population size and its trends (Gust and Griffiths 2009). There has been no robust assessment of the population size of the Platypus either nationwide or for the key states in the species’ geographic range. Lunney et al. (2008) stated that ‘It is a common species’, but noted that ‘in general there is a surprising lack of knowledge about its abundance’. Carrick et al. (2008) considered it ‘common (though rarely abundant)’ but regarded it as ‘potentially vulnerable due to its specialised dependence on established water bodies for food and shelter’. Grant and Temple-Smith (2003) noted that the current and future conservation status of the Platypus is not easily predicted since their abundance is not readily measured. Since abundance is difficult to determine, population trends are generally poorly defined and the impacts of particular threats have been suggested and inferred, but rarely rigorously demonstrated (Gust and Griffiths 2009).

However, there have been some estimates of the number of individuals or of density for (parts of) individual rivers and for some areas. For Kangaroo Island, the size of the introduced subpopulation has been robustly estimated to be about 110 individuals (Furlan et al. 2012), with an effective population size of 11 individuals: this subpopulation was derived from a small number of individuals introduced between 1928 and the 1940s.

Platypus population densities in two reliably perennial rural streams in southern Victoria ranged from 1.3-2.1 subadults and adults per kilometre of channel (Serena 1994; Gardner and Serena 1995). In streams in high quality native forests at Lake Eildon National Park in central Victoria, densities were only 0.1-0.3 subadults and adults recorded per kilometre of perennial stream channel (Serena et al. 2001a, b). In a Tasmanian study of one catchment, catch rates were lower in headwaters than downstream reaches and in areas exposed to previous logging than in unmodified areas (Koch et al. 2006).

The extent of knowledge of population trends, and the trends themselves, have varied across its range. There is little available information on trends in Queensland. In New South Wales, Dickman (1994) noted that it had ‘declined in all regions’; and some studies have demonstrated local declines or even disappearances in recent decades (e.g. Grant and Denny 1991; Grant 1992, 1993, 1998; Rohweder 1992, Rohweder and Baverstock 1999; Lunney et al. 2008; Serena and Williams 2010d). A state-wide survey in 1987-88 concluded that its overall distribution had not changed significantly since the 1950s (Grant and Denny 1991; Grant 1992), and this pattern was broadly evident in some subsequent broad-scale assessment in 1994-96 (Grant et al. 2000). A more detailed and systematic assessment was undertaken in 2006, based on community knowledge (D. Lunney pers. comm. 2013). This concluded that there had been no sharp overall decline, but there were more locations showing decline than increase.

In Victoria, the Platypus is faring far less well, with substantial declines over recent decades. Mark-recapture studies carried out along the Wimmera River and its tributaries indicated that this system (conservatively estimated to have supported >1,500 Platypus at the time of European settlement) supported fewer than 200 individuals by the late 1990s, with numbers declining to <30 individuals by 2007 (Serena and Williams 2007b); juveniles have not been recorded in this system since 2006 (Griffiths and Weeks 2012). Capture frequency in replicated surveys in the Coliban River in central Victoria declined five-fold from 2001 to 2010, presumably due to drought (Williams 2010). It has been lost from several largely self-contained catchments, including the Cardinia Creek system in the mid-1980s (Serena and Williams 2004), the Curdies River system in the mid-1990s (Serena et al. 2002), and the Bass and Avoca River systems in the mid-2000s (Serena and Williams 2007a; M. Serena pers. comm. 2014). In the greater Melbourne area (across four hydrologically independent drainage basins) numerous subpopulations have contracted or become fragmented since 1995 as a by-product of urban or agricultural development and these are continuing to decline (Serena and Williams 2008a; Griffiths et al. 2012). Elsewhere in Victoria, both reduced flow regimes and severe flooding have contributed to the local depletion or disappearance of Platypus subpopulations (e.g. Serena and Williams 2007b, 2008b, 2010c).

There is little information on recent population trends in South Australia (Kangaroo Island). In Tasmania, trapping surveys in 2008-09 indicated that it remains widespread (Geragthy et al. 2011) and occupies a diverse array of water bodies (Gust et al. 2009). The lack of evidence for major reductions in abundance or distribution across Tasmania should be treated cautiously given the insensitivity of existing measures to detect change, the lack of systematic, rigorous monitoring for the species, and the possibility that significant localised declines occurred but went unnoticed (Gust and Griffiths 2010). 

Current Population Trend:Decreasing
Additional data:
Number of mature individuals:30000-300000, 50000Continuing decline of mature individuals:Yes
Extreme fluctuations:NoPopulation severely fragmented:No
Continuing decline in subpopulations:Yes
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:The Platypus is restricted to streams and suitable freshwater bodies, including some shallow water storage lakes and ponds (Carrick et al. 2008). Its food is almost exclusively benthic macroinvertebrates and so the species is water-dependent. Platypuses are largely solitary, and when not foraging in water they normally occupy a resting or nesting burrow in earth banks, although some individuals have been found resting in accumulated stream debris or in low dense vegetation. The species is seldom observed moving on land in mainland Australia, but is frequently seen out of the water in Tasmania, where its predator, the fox (Vulpes vulpes), has been introduced only relatively recently (T. Grant, S. Munks, F. Carrick, and M. Serena pers. comm. 2014). The breeding season varies widely depending on location. Females produce one to three eggs annually, but usually two (Carrick et al. 2008). Platypuses are long-lived animals (up to 20 years in the wild).
Systems:Terrestrial; Freshwater
Continuing decline in area, extent and/or quality of habitat:Yes
Generation Length (years):9-12
Movement patterns:Not a Migrant

Use and Trade [top]

Use and Trade: Formerly (mostly before the 20th century) hunted for pelts; and this trade may have affected the status of some subpopulations (Burrell 1927; Grant and Denny 1991)

Threats [top]

Major Threat(s): Currently, the predominant threat to the species on the mainland is reduction in stream and river flows due to recent successive droughts, stream regulation, and extraction of water for agricultural, domestic, and industrial supplies. It is also at risk from the opposite extremes associated with climate change – extensive flooding both in space and time associated with recent tropical cyclones that have resulted in increased mortality and all but eliminated recruitment in 2006 over a substantial part of the species’ northern range. Habitat modification due to bank erosion and stream sedimentation (as a result of poor land management practices in agriculture, forestry, and urbanization) are also of great concern. In the case of urban streams, Platypus populations may be adversely affected by poor water quality (in the form of suspended solids and nutrient enrichment), contamination of sediment by heavy metals (Serena and Pettigrove 2005) and entanglement in or ingestion of plastic, rubber and metal litter. Accidental drowning in nets and traps set for fish and crustaceans has the potential to impact Platypus distribution and abundance in all parts of its range, especially in small streams where populations may be critically small. Populations in Tasmania are affected by mucormycosis (associated with the fungal pathogen Mucor amphibiorum) (Obendorf et al. 1993). Across its range, the Platypus is also subject to predation by the introduced Red Fox, dogs and cats.

Conservation Actions [top]

Conservation Actions: Conservation of the Platypus is limited to its listing as a legally protected species in all states in which it occurs and its incidental inclusion in some national parks and reserves. Legislation prohibiting or controlling problematic fishing activities has been enacted in New South Wales and Victoria, but regulations concerning illegal netting and trapping are often poorly enforced. The most widespread field monitoring program for the species is in Victoria (Australian Platypus Conservancy). There are also a few system-specific studies in other states and community-based reporting of anecdotal occurrences of the species to a variety of institutional and private databases. Still more information about population numbers and monitoring are crucial, especially for a long-lived species such as the Platypus where a lack of recruitment can be masked until a dramatic population crash occurs as adults reach the end of their lifespan.

Population studies of fragmented populations should be a research priority, together with studies to help verify the current distribution and baseline population parameters in areas where the species has declined (Grant and Temple-Smith 2003). Once the Platypus becomes extinct in a river system, the likelihood of its re-colonising that system without human intervention is minimal (T. Grant, S. Munks, F. Carrick, and M. Serena pers. comm. 2014). One reintroduction program is underway in a single fire-affected stream in Victoria (Australian Platypus Conservancy).

Some populations of Platypuses have exhibited antibodies to Leptospirosis, probably transmitted via cattle, but no clinical symptoms have been observed. Mortality from an ulcerative dermatitis caused by Mucor fungus, however, has been recorded across many river systems in Tasmania. There is currently limited investigation of this disease, which should be a research priority both in that state and on the mainland where the fungus is also found (T. Grant, S. Munks, F. Carrick, and M. Serena pers. comm. 2014).

Citation: Woinarski, J. & Burbidge, A.A. 2016. Ornithorhynchus anatinus. The IUCN Red List of Threatened Species 2016: e.T40488A21964009. . Downloaded on 16 August 2018.
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