An analysis of nearly 400 platypus mortalities reported to the APC from the 1980s to mid-2024 (mainly from sites on the Australian mainland, especially Victoria) found that animals died most often after drowning in nets or traps set to capture fish or crayfish/yabbies (as shown at right, 55% of all mortalities). However, the good news was that both platypus and rakali deaths in opera house traps in Victoria dropped very markedly after a statewide ban on the recreational use of enclosed yabby traps came into effect in mid-2019 (Serena et al. 2025). 
Apart from nets and traps, the impact of various platypus mortality factors was as follows:
- Predation by foxes, dogs or birds of prey – 13% of victims
- Embedded fishing hooks or discarded fishing line – 9% of victims
- Entanglement in other sources of litter – 6% of victims (as shown above)
- Run over by a motor vehicle – 6% of victims (as shown below)
- Sucked into irrigation pumps or mini-hydro turbines – 3% of victims
- Entrapment in other manmade structures – 2% of victims
- Flooding – 2% of victims
- Drought – 2% of victims
- Other causes (such as juveniles dug up during earth-moving works) – 2% of victims
This link can be used to read or download all of the study’s findings: https://www.publish.csiro.au/AM/AM24026.
By comparison, a study of factors contributing to 23 Tasmanian platypus mortalities in the mid-1990s concluded that the most common cause of death was attack by domesticated dogs (43% of victims).
This was followed by being run over by a car (30% of victims), starvation or exposure due to natural causes such as flooding (17% of victims) and infection by Mucor amphibiorum, an ulcerative fungal disease that was first recorded in Tasmanian platypus in 1982 (9% of victims) (Connolly et al. 1998).
Differences in the findings from the two studies reflect the fact that:
- Use of crayfish/yabby traps was undoubtedly much less widespread in Tasmania than on the mainland (reflecting differences in state fishing regulations).
- Foxes were not present in Tasmania in the mid-1990s.
- There are no known cases of platypus on the mainland becoming sick due to infection by Mucor (Connolly et al. 1998). Interestingly, the frequency of Mucor cases has dropped markedly over time, with the average prevalence of infected animals in affected catchments declining from 30% (between 1994 and 2000) to 7% (from 2008 to 2009) (Gust et al. 2009) and very few cases reported since around 2016.
- As compared to mainland platypus, Tasmanian animals are known to spend more time travelling across land and therefore are more at risk of being attacked by pet dogs or hit by cars.
Photos courtesy of B. McNamara (top); Wildlife Victoria (middle); J. Pammer (bottom)
LITERATURE CITED
Connolly JH, Obendorf DL, Whittington RJ and Muir DB (1998) Causes of morbidity and mortality in platypus (Ornithorhynchus anatinus) from Tasmania, with particular reference to Mucor amphibiorum infection. Australian Mammalogy 20, 177-187.
Gust N, Griffiths J, Driessen M, Philips A, Stewart N and Geraghty D (2009) Distribution, prevalence and persistence of mucormycosis in Tasmanian platypuses (Ornithorhynchus anatinus). Australian Journal of Zoology 57, 245-254.
Serena M, Williams GA and Thomas JL (2025) Factors contributing directly to platypus (Ornithorhynchus anatinus) mortality and implications for conserving populations in the wild. Australian Mammalogy 47, AM24032.