A national assessment of the conservation status of the platypus Assessors: Tahneal Hawke, Gilad Bino, Richard T. Kingsford. Contributors: Tom Grant, Josh Griffiths, Andrew Weeks, Reid Tingley, Emily McColl-Gausden, Melody Serena, Geoff Williams, Tamielle Brunt, Luis Mijangos, William Sherwin, Jessica Noonan. Acknowledgements: This report was funded through a research grant from the Australian Conservation Foundation (ACF) in collaboration with WWF-Australia and Humane Society International (HSI). Date: 17/11/2020 We acknowledge the Traditional Owners of this country and their continuing connection to land, waters and community. We pay respect to elders both past and present. Table of Contents Table of Contents ....................................................................................................................... 2 Table of Figures ......................................................................................................................... 4 Table of Tables .......................................................................................................................... 7 Executive summary .................................................................................................................... 8 Taxonomy ................................................................................................................................ 10 IUCN threated species assessment status ................................................................................ 10 EPBC threatened species assessment status ............................................................................ 10 Species description ................................................................................................................... 10 The platypus in Indigenous culture .......................................................................................... 11 Utilization of taxon .................................................................................................................. 11 Geographic Range .................................................................................................................... 12 Countries of occurrence ....................................................................................................... 12 Historic distribution ............................................................................................................. 12 Change in distribution .......................................................................................................... 15 Habitat and ecology (see Appendix for additional information) ............................................. 22 Systems ................................................................................................................................ 22 Generation length ................................................................................................................. 22 Ecology ................................................................................................................................ 22 Habitat .................................................................................................................................. 23 Population ................................................................................................................................ 24 Historical numbers ............................................................................................................... 24 Contemporary numbers ........................................................................................................ 26 Population trends ................................................................................................................. 33 Case study: Greater Melbourne region ............................................................................ 38 Rate of reduction .................................................................................................................. 42 Estimated current population size ........................................................................................ 42 2 Extinction probability and viability models ......................................................................... 46 Threats (See Appendix for additional information) ................................................................. 59 Vegetation clearing .............................................................................................................. 59 Urbanisation ......................................................................................................................... 61 River regulation ................................................................................................................... 62 Fishing by-catch, predation & pollution .............................................................................. 65 Disease ................................................................................................................................. 65 Climate change..................................................................................................................... 65 Cease to flow and drought ................................................................................................... 70 Bushfires .............................................................................................................................. 71 Conservation ............................................................................................................................ 74 Conservation actions in place (See Appendix for additional information) .......................... 74 Monitoring actions in place ................................................................................................. 75 Conservation actions needed (See Appendix for additional information) ........................... 75 Summary criteria for platypus ................................................................................................. 76 A. Population size reduction ............................................................................................. 77 B. Geographic range .......................................................................................................... 77 C. Small population size and decline ................................................................................ 77 D. Very small population size and decline ....................................................................... 78 E. Quantitative analysis ..................................................................................................... 78 Potential listing category ................................................................................................... 78 References ................................................................................................................................ 79 Appendix .................................................................................................................................. 89 Appendix 1 ........................................................................................................................... 89 Appendix 2 ........................................................................................................................... 93 Appendix 3 ........................................................................................................................... 95 3 Table of Figures Figure 1. All reported sightings of platypuses (Atlas data bases, iNaturalist, museum records, Trove, platypusSPOT; 1770-2020; green since 1990, red prior to 1990), currently used distribution by IUCN (light grey\black outline), and proposed updated distribution (light blue). .................................................................................................................................................. 13 Figure 2. a) Sub-catchments (Hybas7) with platypus records (1770-2020) and b) Sub- catchments intersecting with the current IUCN distribution for platypus (blue line). ............. 15 Figure 3. Last year of platypus record in each sub-catchment (HydroBASIN Level 7) across the distribution of platypus. ..................................................................................................... 19 Figure 4. Last year of platypus record in each of the sub-catchments (HydroBASIN Level 8). .................................................................................................................................................. 20 Figure 5. Sub-catchments (HydroBASIN Level 7) where platypus have not been detected (red outline) and where they have been detected (green outline) using eDNA sampling. .............. 21 Figure 6. The distribution and number of studies (peer reviewed articles, reports, and theses) across the distribution of the platypus. .................................................................................... 27 Figure 7. The average catch per hour (± SD) of platypuses across years (1992-2018) for a) different states: NSW (blue), VIC (orange) and Tasmania (grey) and b) different net type: mesh nets (red ), fyke nets (blue), and combined nets (green). ......................................................... 31 Figure 8 Proportion of platypus records since 1990 (n=12,513) by decade in each of the 270 sub-catchments ......................................................................................................................... 34 Figure