A third wet year helped post-fire recovery and wetland communities, but biodiversity continues to decline
Three consecutive years of high rainfall and widespread flooding had mixed effects on biodiversity. As wetlands filled across south- eastern Australia, waterbird numbers nearly doubled from the previous year. On the other hand, high sediment runoff impacted seagrass meadows along the Queensland coast, leading to the starvation of dugongs and the threatened green sea turtle.
The Threatened Species Index (TSX) estimates the changing abundance of threatened and near- threatened species with a three-year lag. Estimates for 2019 (before the Black Summer fires) show a continued decline in the abundance of Australia’s threatened birds, mammals and plants.
Among species listed as threatened on the Environmental Protection and Biodiversity Conservation Act (EPBC Act) and included in the TSX, abundance in 2019 was 62% lower than the year 2000, with an average annual rate of decline of 3%. Threatened plants showed the greatest declines (72%), followed by birds (62%) and mammals (33%).
According to the TSX, species protection and management have been effective at slowing declines, and even stabilising and recovering some species. For example, the abundance of mammals at actively managed sites remained stable at
24% below 2000 values, whereas those without protection declined by 44% since 2000.
The abundance of medium-sized mammals — considered the most at risk due to fox and cat predation — has stabilised due to intensive management, while that of large mammals increased by 105% since 2000 on average, with significant recovery of humpback and southern right whales contributing to this trend.
Another 30 species were added to the EPBC Act List of Threatened Species, bringing the total number to 1,973 — a 43% increase since 2000. Eight species were uplisted. Currently, 5.7% of Australian plants and 5.9% of animals are threatened with extinction.
All eight uplisted species and 24 of the 30 newly listed species were affected by the 2019/2020 Black Summer fires. The entire range of some plant species was burnt, putting them at immediate risk of extinction. The bushfires also compounded existing threats for many other species. For example, the Mount Kaputar rock skink and the gang gang cockatoo were listed as Endangered for the first time. Some species were less impacted than feared: land snails in northern NSW were remarkably resilient, with just 3 of 30 species identified as of conservation concern due to the fires.
Abundance of different categories of threatened species since 2000 (source: Threatened Species Index)
No species were declared extinct in 2022 under the EPBC Act, and only two were downlisted. The humpback whale was removed from the list due to a remarkable population recovery. In the history of the threatened species list, only 14 species have recovered sufficiently to be delisted and two of those were subsequently re-added. Over 130 new species were discovered in 2022. A new species of mountain frog from the Gondwana Rainforests (Philoria knowlesi) was
described and is likely to be listed as Endangered. NSW acquired a new endemic legless lizard, the Hunter Valley delma (Delma vescolineata). Other discoveries included an earthworm, four orchids, two lava cave weevils, eleven jumping spiders, seven pseudo-scorpions, and a shark.