Australia

Australia is one of just 17 megadiverse countries — together barely 10% of the planet's land surface, yet home to more than 70% of its biodiversity (DCCEEW) — and a wealthy, highly urbanised continent, with more than 96% of its people living in towns and cities (Australia State of the Environment 2021). Tens of millions of years of biogeographic isolation, since the deep-water Tasmanian Gateway opened between Australia and Antarctica at the Eocene–Oligocene transition roughly 34–33 million years ago (Stickley et al. 2004), produced a biota found largely nowhere else: about 90% of its reptiles and 93% of its frogs are endemic, along with the great majority of its mammals and close to half its birds (Australia State of the Environment 2021), and whole lineages such as the monotremes and marsupials radiated here in isolation (DCCEEW).

That same isolation left the fauna acutely vulnerable to introduced predators. The result is the heaviest modern mammal loss of any continent: 33 native mammal species have been driven extinct since European settlement in 1788 (DCCEEW), among 104 extinctions across all taxa recognised under national environmental law (DCCEEW). SpeciesRadar tracks 2,036 Australian species in IUCN threatened categories, of which 331 are Critically Endangered and 1,097 have declining populations (IUCN Red List 2025).

The dominant driver of decline is invasive species. Feral cats are now present across about 99.9% of Australia and on all land tenures, absent only from fenced exclosures and some islands; with the introduced European red fox they are implicated in most of the continent's historical mammal extinctions and continue to suppress native wildlife (DCCEEW, Threat Abatement Plan for Predation by Feral Cats 2024; Australia State of the Environment 2021). Rabbits, cane toads, introduced herbivores and invasive grasses degrade habitat and reshape food webs — the European rabbit alone threatening an estimated 21% of nationally listed species (Australia State of the Environment 2021).

Habitat loss runs a close second: land clearing for expanding agriculture and urbanisation is a leading pressure on threatened species, and the south-west of Western Australia ranks among the world's biodiversity hotspots for its concentration of endemic plants (Australia State of the Environment 2021).

Altered fire regimes compound these pressures: the 2019–20 ‘Black Summer’ bushfires burned more than 8 million hectares of native vegetation across south-eastern Australia, pushing many already-listed species closer to extinction (Godfree et al. 2021). Marine systems are under parallel strain.

The Great Barrier Reef — the world's largest coral reef system and a UNESCO World Heritage Area inscribed in 1981 (GBRMPA) — has suffered five mass coral-bleaching events since 2016 (2016, 2017, 2020, 2022 and 2024), driven by marine heatwaves and compounded by intensified cyclones and land-based runoff; the IUCN World Heritage Outlook now rates its conservation prospects as ‘Critical’, with climate change the most significant and intensifying threat (IUCN World Heritage Outlook 2025).

Australia assesses and lists its own threatened species under the Environment Protection and Biodiversity Conservation Act 1999, with more than 1,910 species listed and a national framework distinct from the global IUCN Red List — including the category ‘Conservation Dependent’, which has no IUCN equivalent (DCCEEW). The national response, coordinated through the Threatened Species Action Plan 2022–2032, leans on two pillars: a network of predator-free islands and fenced ‘safe havens’ holding insurance populations of species such as the greater bilby (IUCN: Vulnerable) and numbat (IUCN: Endangered) — 17 fenced and 101 island havens supporting 188 populations of 38 threatened mammal taxa as of 2018 (Legge et al. 2018) — and Indigenous-led management, with Indigenous Protected Areas now the largest single component of the National Reserve System (DCCEEW).

Despite these efforts the overall trajectory is deteriorating: entrenched invasive predators, intensifying fire and marine heat, and continued habitat loss are outpacing recovery (IUCN Red List 2025).