Published: May 2023.
Extinctions are holes torn in the fabric of life, and Australia is ragged from so many species ripped out. We are missing far more mammals than any other continent, as well as frogs, lizards, fishes, insects and plants. Many losses are recent.
This report examines the causes of modern extinctions in Australia – all recent extinctions and probable extinctions – to find that invasive species have caused the vast majority of losses since 1960. There have been 21 probable extinctions of animals and 4 of plants, averaging 4 extinctions per decade. Of the 23 losses for which experts have assigned causes, 17 (73%) were due mainly to invasive species. If we consider animal extinctions on their own, 17 of the 19 (89%) were due mainly to invasive species. The 4 likely plant extinctions are blamed mainly on habitat destruction or degradation.
The main agents of modern extinction have been chytrid fungus (removing 6 species) and wolf snakes (4 species). The other agents have been cat, fox, black rat, brown trout and a trypanosome blood parasite.
Habitat loss is often cited as the main cause of extinctions, but that is untrue of recent extinctions in Australia. That conclusion was reached some years back because of long lists of plants putatively extinct from habitat loss. More effort put into searches has led to many rediscoveries of these. The current numbers mean that invasive species have caused a majority of all extinctions since European arrival.
The figures and percentages given here update those that appear in the report. Since its publication in May 2023, two ‘probably extinct’ lizards have been rediscovered: the Victorian grassland earless dragon and Lyon’s grassland striped skink. They feature in the report as the only animal extinctions attributed to habitat destruction or degradation.