Lesser Swamp-orchid (Phaius australis). Photo credit: Nicolas Rakotopare.
25 November 2025
The Threatened Species Index 2025
The TSX brings together thousands of monitoring datasets from across Australia and releases trend updates annually. In 2025, along with updates to the existing groups (amphibians, birds, mammals, and plants), a pilot Threatened Reptile Index has been created. Key results across all groups are described below.
Key Results: National Trend
At the national scale, threatened and near-threatened species have experienced significant long-term losses, with an average decline of 75% in relative abundance since 1985 for the 395 taxa represented. Overall, the abundance of threatened and near-threatened species in the TSX dataset has declined by 1.6% per annum between 2000 and 2022. The full set of trends for the 2025 index can be explored using the TSX trend visualiser tool below.
TSX Trend Visualiser ToolFigure 1 (right): The Threatened Species Index 2025, showing trends up to 2022 across all taxa and separately for birds, mammals, plants, amphibians and reptiles. Each line shows the average change in relative abundance compared to the baseline year of 1985 where the index value is set to 1.
Bird TAXA
MAMMAL TAXA
PLANT TAXA
AMPHIBIAN TAXA
REPTILE TAXA
EPBC LISTED TAXA
IUCN LISTED TAXA
NUMBER OF TIME SERIES
NUMBER OF SOURCES
Key Results: Species Groups
The TSX currently includes data for threatened and near-threatened birds, mammals, plants, amphibians and reptiles.
BIRDS
The trend for birds follows a similar shape to the main index, with an average decline in relative abundance of 56% since 1985 across the 73 taxa represented. Overall, birds have declined by an average 1.8% per annum between 2000 and 2022.
Figure 2: The Threatened Species Index 2025 based on all data provided on threatened and near-threatened bird taxa. The blue line shows the average change in relative abundance compared to the baseline year of 1985 where the index value is set to 1. The shaded areas show the confidence limits.
MAMMALS
Across the 92 mammal taxa for which the TSX has data, the average decline in relative abundance is 38% since 1985. Overall, mammals have declined by an average 1.5% per annum between 2000 and 2022 but have displayed an overall relatively stable trend since 2005.
Figure 3: The Threatened Species Index 2025 based on all data provided on threatened and near-threatened mammal taxa. The orange line shows the average change in relative abundance compared to the baseline year of 1985 where the index value is set to 1. The shaded areas show the confidence limits.
PLANTS
Across the 178 plants for which TSX data are available, there was an average decline in relative abundance of 73% since 1985. Overall, plants have declined by an average 2.5% per annum between 2000 and 2022.
Figure 4. The Threatened Species Index 2025 based on all data provided on threatened and near-threatened plant taxa. The green line shows the average change in relative abundance compared to the baseline year of 1985 where the index value is set to 1. The shaded areas show the confidence limits.
AMPHIBIANS
The trend for amphibians shows a precipitous decline through to 2000. For the 28 taxa covered by the current dataset, relative abundance has declined by 97% on average since 1985. Overall, amphibians have declined by an average 0.2% per annum between 2000 and 2022.
Figure 5. The Threatened Species Index 2025 based on all data provided on threatened and near-threatened amphibian taxa. The yellow line shows the average change in relative abundance compared to the baseline year of 1985 where the index value is set to 1. The shaded areas show the confidence limits.
REPTILES
The trend for reptiles shows a near-linear decline through to 2005. For the 24 taxa covered by the current dataset, relative abundance has declined by 94% on average since 1985. Overall, reptiles have declined by an average 2.1% per annum between 2000 and 2022.
Figure 6: The Threatened Species Index 2025 based on all data provided on threatened and near-threatened reptile taxa. The brown line shows the average change in relative abundance compared to the baseline year of 1985 where the index value is set to 1. The shaded areas show the confidence limits.
Key Results: States and Territories
Considering the significant variation in species and ecosystems represented by Australia’s States and Territories, there is remarkable consistency in trends. South Australia, Queensland, Western Australia, and New South Wales and the Australian Capital Territory (combined) show average declines in relative abundance ranging from 47% to 59% since 2000. Victoria and the Northern Territory exhibited the most pronounced losses, both with an average decline of 62% in the relative abundance of threatened and near-threatened species since 2000. In contrast, data held for Tasmania suggest an average decline of 33% across the 35 taxa represented for the state.
Figure 7: The Threatened Species Index 2025 for each State and Territory between 2000 and 2022; A) Victoria, B) the Northern Territory, C) Queensland, D) Western Australia, E) South Australia, F) New South Wales and the Australian Capital Territory, and G) Tasmania. The green lines show the average change in relative abundance compared to the baseline year of 2000 where the index value is set to 1. The shaded areas show the confidence limits.
Additional Resources
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