When I pulled up the Threatened Species Index data, the first thing I noticed was how far the line had dropped. Threatened species populations are now sitting at about 25% of where they were in 1985 (TERN & DCCEEW, 2025). I went into this expecting a bad trend. I wasn’t expecting it to be that consistent. What the EPBC listing data shows on top of that is 2,098 species currently classified as Vulnerable, Endangered, or Critically Endangered (DCCEEW, 2026), and every animal group I looked at has more entries in 2026 than it did in 2011 (Department of the Environment, 2016).

Chart 1: The Long Decline in Population Abundance

Australia’s threatened species populations have lost roughly three-quarters of their abundance since 1985 (TERN & DCCEEW, 2025).

Source: Threatened Species Index 2025 (TSX), TERN/DCCEEW. Index value = 1.0 at 1985 baseline. Shaded band shows 95% confidence interval. Covers all threatened and near-threatened species with sufficient monitoring data.

Chart 2: Flora vs Fauna, Different Scale, Same Trajectory

Plants make up most of the threatened species list by count, but when you look inside the animal group, a bigger share of them are Critically Endangered (DCCEEW, 2026).

Source: DCCEEW EPBC Act Threatened Species List, extracted 6 February 2026. Excludes Extinct and Conservation Dependent listings. Total: 2,098 species (1,479 flora; 619 fauna).

Chart 3: Every Animal Group Has Grown Since 2011

Every animal group on the EPBC list has more species on it now than in 2011, and birds went from 109 to 164 listed species over fifteen years (Department of the Environment, 2016; DCCEEW, 2026).

Sources: 2011 and 2015 data from Department of the Environment (2016). Number of fauna species listed under the EPBC Act in 2011 and 2015 [SoE 2016 dataset]. data.gov.au. 2026 data derived from DCCEEW EPBC Act Threatened Species List (February 2026). Fish includes Actinopterygii and Chondrichthyes.

Chart 4: Where the Burden Falls

New South Wales carries more threatened species than any other state, followed closely by Western Australia and Queensland (DCCEEW, 2026).

Source: DCCEEW EPBC Act Threatened Species List, extracted 6 February 2026. A species occurring in multiple states is counted once per state. Territories and offshore areas excluded.

Chart 5: The Groups Facing the Sharpest Threat

More than one in three threatened amphibians and fish are Critically Endangered, the worst breakdown of any animal group in the data (DCCEEW, 2026).

Source: DCCEEW EPBC Act Threatened Species List, extracted 6 February 2026. Vertebrate classes only (Mammalia, Aves, Reptilia, Amphibia, Actinopterygii, Chondrichthyes). Percentages show share of each group’s total threatened listings.

Acknowledgements

I used Claude (Anthropic, 2026) to help with some parts of the R code where I got stuck, mainly for fixing syntax errors and tidying up the plotly formatting. All the decisions in this assignment, including choosing the visualisations, sourcing and processing the data, and writing the narrative, are my own work. I’ve referenced Claude below in line with RMIT Library’s AI referencing guidelines.

Anthropic. (2026). Claude (claude-sonnet-4-6) [Large language model]. https://claude.ai

For referencing guidelines, see: RMIT Library. (n.d.). Artificial intelligence (AI): Acknowledgement and referencing guidelines. https://rmit.libguides.com/referencing_AI_tools

References

Department of the Environment. (2016). Number of fauna species listed under the EPBC Act in 2011 and 2015 [SoE 2016 biodiversity dataset]. Australian Government. https://data.gov.au/data/dataset/2016-soe-biodiversity-epbc-listed-fauna-species-2011-and-2015

Department of Climate Change, Energy, the Environment and Water. (2026, February 6). Threatened species and ecological communities of national environmental significance [Data file]. Australian Government. https://data.gov.au/data/dataset/ae652011-f39e-4c6c-91b8-1dc2d2dfee8f

TERN & Department of Climate Change, Energy, the Environment and Water. (2025). The Australian Threatened Species Index 2025 [Data file]. https://tsx.org.au/tsx2025/

Sievert, C. (2020). Interactive web-based data visualization with R, plotly, and shiny. Chapman and Hall/CRC. https://plotly-r.com

Wickham, H., Averick, M., Bryan, J., Chang, W., McGowan, L. D., François, R., Grolemund, G., Hayes, A., Henry, L., Hester, J., Kuhn, M., Pedersen, T. L., Miller, E., Bache, S. M., Müller, K., Ooms, J., Robinson, D., Seidel, D. P., Spinu, V., & Yutani, H. (2019). Welcome to the tidyverse. Journal of Open Source Software, 4(43), 1686. https://doi.org/10.21105/joss.01686