Kangaroo Island dunnart cat predation following bushfire

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Kangaroo Island (~4400 km2, hereinafter KI) is the third largest island in Australia. It suffered extensive clearing and consequent fragmentation of the natural bush habitat after World War II.1.2. The relatively intact western KI has finally been identified as a key biodiversity hotspot3home to several endangered and endemic native species, including the KI dunnart.

Dunnarts (Sminthopsis spp.) are small insectivorous dasyurid marsupials. The KI dunnart can be distinguished from the other 17 species of dunnart found in Australia by morphological characteristics, including the shape of the manus, pes and penis.4. This endangered species is the only dasyurid found on the island, residing exclusively ~342 km2 before 20205and found nowhere else in the world2. The species is rarely recorded, with only 28 individuals found during >33,000 trapping nights prior to 20195. With a low number of individuals confined to a small geographic area, the KI dunnart is exceptionally vulnerable to stochastic events. Predation by feral cats (Felis catus) is likely to be another source of pressure on KI dunnart. Cats were introduced to KI during European colonization and quickly became apex predators, reaching a higher relative abundance than the adjacent continent.6 with an estimated density of 0.37 ± 0.15 cat/km25. Cat predation has caused the extinction or near extinction of several native species around the worldseven, with the risk of extinction becoming increasingly acute in island islands like KI. Predation by cats on islands has contributed to >13% of recorded extinction events globally, accounting for >8% of cases within these species taxa pushed to Critically Endangered status8. A recent meta-analysis found evidence of cat predation for three Critically Endangered and four Endangered species in Australia on the IUCN Red List of Threatened Speciesseven.

Australian bushfires in 2019-2020 burned ~97,000 km2 vegetation9.10, with damage overlapping the habitats of > 100 threatened species. Dry thunderstorms in the remote, vegetated northwest of the island sparked the KI bushfire. The bushfire eventually spread eastward, burning approximately 98% of known and predicted KI dunnart habitatten.

In this study, we analyzed the diet of humanely euthanized feral cats in designated areas of local conservation interest immediately after the 2019 KI bushfire.

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