Feral cats likely kill far more Australian native animals than we thought: first DNA analysis

Feral cats in Australia are likely responsible for killing significantly more native animals than previously believed, according to groundbreaking research that uses DNA analysis to examine the diets of feral cats. The study, conducted in the Wild Deserts conservation reserve in New South Wales, marks the first time DNA methods have been applied to cat diet studies in Australia. Traditional methods of analyzing stomach contents and scat samples have long underestimated the impact of feral cats on native wildlife, particularly for small or soft-bodied species. The research team employed both manual examination and DNA metabarcoding techniques to analyze the stomach contents of feral cats culled from the Wild Deserts area. DNA metabarcoding involves identifying genetic material from prey species present in the cat's digestive system, allowing for the detection of even minute traces of animals that would otherwise go unnoticed. This approach proved highly effective in identifying a greater variety of species compared to conventional methods. DNA analysis revealed twice as many mammal species and three times as many bird species in the cats' stomachs than manual inspection alone. Traditional methods rely on visual identification of physical remains such as bones, feathers, or fur, which can be challenging due to rapid digestion and decomposition. As a result, more than half of the prey remains studied were either too degraded or too small to identify accurately. This limitation suggests that current estimates of the number of native animals killed by feral cats may be significantly lower than the actual figure. The study highlights how DNA-based methods offer a more reliable and comprehensive way to assess the dietary habits of feral cats. The findings underscore the severity of the threat posed by feral cats to Australia's biodiversity. Over the past 238 years, more than 40 native mammal species have gone extinct, making Australia's conservation crisis one of the worst in the world. Currently, nearly 700 species face the risk of extinction, with at least 200 of them directly threatened by feral cats, alongside other factors such as habitat destruction, disease, and invasive species. Feral cats are estimated to kill more than 1.5 billion native animals annually, based on prior studies that examined stomach contents and scat. The researchers noted that while DNA analysis was highly successful in detecting small mammals and birds, it was less effective for certain reptile species. This discrepancy could be attributed to differences in the composition of DNA or the presence of contaminants in the stomach contents. Despite this, the overall results indicate that the true scale of predation by feral cats may be much larger than previously assumed. Conservation efforts such as predator-free fenced reserves, often called safe havens, are considered crucial for protecting vulnerable native species. These areas, including projects like Arid Recovery, Wild Deserts, Secret Rocks, and others managed by organizations such as the Australian Wildlife Conservancy and NSW National Parks, have successfully reintroduced species that were once locally extinct. However, fencing large portions of Australia is impractical, leaving many native animals exposed to threats from introduced predators like feral cats. As the research team continues to explore the implications of their findings, the data will inform strategies aimed at better understanding and mitigating the impact of feral cats on Australia's ecosystems. The application of DNA analysis in wildlife management represents a promising step toward more accurate assessments of predator-prey interactions and the preservation of native biodiversity.