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Abstract ContextRecent global concern over invertebrate declines has drawn attention to the causes and consequences of this loss of biodiversity. Feral cats, Felis catus, pose a major threat to many vertebrate species in Australia, but their effect on invertebrates has not previously been assessed. AimsThe objectives of our study were to (1) assess the frequency of occurrence (FOO) of invertebrates in feral cat diets across Australia and the environmental and geographic factors associated with this variation, (2) estimate the number of invertebrates consumed by feral cats annually and the spatial variation of this consumption, and (3) interpret the conservation implications of these results. MethodsFrom 87 Australian cat-diet studies, we modelled the factors associated with variation in invertebrate FOO in feral cat-diet samples. We used these modelled relationships to predict the number of invertebrates consumed by feral cats in largely natural and highly modified environments. Key resultsIn largely natural environments, the mean invertebrate FOO in feral cat dietary samples was 39% (95% CI: 31–43.5%), with Orthoptera being the most frequently recorded order, at 30.3% (95% CI: 21.2–38.3%). The highest invertebrate FOO occurred in lower-rainfall areas with a lower mean annual temperature, and in areas of greater tree cover. Mean annual invertebrate consumption by feral cats in largely natural environments was estimated to be 769 million individuals (95% CI: 422–1763 million) and in modified environments (with mean FOO of 27.8%) 317 million invertebrates year−1, giving a total estimate of 1086 million invertebrates year−1 consumed by feral cats across the continent. ConclusionsThe number of invertebrates consumed by feral cats in Australia is greater than estimates for vertebrate taxa, although the biomass (and, hence, importance for cat diet) of invertebrates taken would be appreciably less. The impact of predation by cats on invertebrates is difficult to assess because of the lack of invertebrate population and distribution estimates, but cats may pose a threat to some large-bodied narrowly restricted invertebrate species. ImplicationsFurther empirical studies of local and continental invertebrate diversity, distribution and population trends are required to adequately contextualise the conservation threat posed by feral cats to invertebrates across Australia.

Aim: After environmental disasters, species with large population losses may need urgent protection to prevent extinction and support recovery. Following the 2019-2020 Australian megafires, we estimated population losses and recovery in fire-affected fauna, to inform conservation status assessments and management. Location: Temperate and subtropical Australia. Time period 2019-2030 and beyond. Major taxa: Australian terrestrial and freshwater vertebrates; one invertebrate group. Methods: From > 1,050 fire-affected taxa, we selected 173 whose distributions substantially overlapped the fire extent. We estimated the proportion of each taxon's distribution affected by fires, using fire severity and aquatic impact mapping, and new distribution mapping. Using expert elicitation informed by evidence of responses to previous wildfires, we estimated local population responses to fires of varying severity. We combined the spatial and elicitation data to estimate overall population loss and recovery trajectories, and thus indicate potential eligibility for listing as threatened, or uplisting, under Australian legislation. Results: We estimate that the 2019-2020 Australian megafires caused, or contributed to, population declines that make 70-82 taxa eligible for listing as threatened; and another 21-27 taxa eligible for uplisting. If so-listed, this represents a 22-26% increase in Australian statutory lists of threatened terrestrial and freshwater vertebrates and spiny crayfish, and uplisting for 8-10% of threatened taxa. Such changes would cause an abrupt worsening of underlying trajectories in vertebrates, as measured by Red List Indices. We predict that 54-88% of 173 assessed taxa will not recover to pre-fire population size within 10 years/three generations. Main conclusions We suggest the 2019-2020 Australian megafires have worsened the conservation prospects for many species. Of the 91 taxa recommended for listing/uplisting consideration, 84 are now under formal review through national processes. Improving ...